In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by...
Polar Covalent Bonds
If the pH of a solution is decreased from 6 to 5, it means that the
Concentration of H+ has increased tenfold (10x) and the concentration of OH- has decreased to one-tenth (1/10) what they were at pH6.
Buffers are substances that help resist shifts in pH by
Both donating H+ to a solution when bases are added, and accepting H+ when acids are added.
The element present in all organic molecules is
Carbon
Polysaccharides, triacyglycerides, and proteins are similar in that they
Are synthesized from subunits by dehydration synthesis.
If a DNA sample were composed of 20% thymine, what would be the percentage of guanine?
30%
Which of the following are nitrogenous bases of the purine type?
Guanine and Adenine
Which of the following best fits the class of molecules known as nucleotides?
A nitrogenous base, a phosphate group, and a pentose sugar.
What kinds of molecules pass through a cell membrane most easily?
Small and Hydrophobic
The membranes of winter wheat are able to remain fluid when it is extremely cold by
Increasing the percentage of unsaturated phospholipids in the membrane.
Diffusion
Is a passive process in which molecules more from a region of higher concentration to a region of lower concentration.
Which of these are NOT embedded in the hydrophobic portion of the lipid bi-layer?
Peripheral Proteins
Which of the following membrane activities requires energy from ATP?
Movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular.
Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?
Catabolism
The mathematical expression for the change in free energy of a system is ?G =?H - T?S. Which of the following is (are) correct?
?S is the change in entropy, a measure of randomness (chaos.)
A chemical reaction that has a positive ?G is correctly described as
endergonic
Why is ATP an important molecule in metabolism?
It provides energy coupling between exergonic and endergonic reactions.
A series of enzymes catalyze the reaction X to Y to Z to A. Product A binds to an enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme
With respect to the enzyme that converts X to Y, pro
An allosteric inhibitor
What is the order of embryonic development?
Zygote, Cleavage, Blastula, Blastocoel, and Gastrulation, Larvae
What is the correct order of reproductive maturity?
Larvae then Metamorphosis then Juveniles
About 25 of the 92 natural elements known to be essential life. Which four of these 25 elements make up approximately 96% of living matter?
Carbon, Hydrogen, Nitrogen, and Oxygen
Molybdenum has an atomic number of 42. Several common isotopes exist, with mass numbers from 92-100. Therefore, which of the following can be true?
Molybdenum atoms can have between 50 and 58 neutrons.
Nitrogen (N) is much more electronegative than hydrogen (H). Which of the following statements is correct about the atoms in ammonia (NH3)?
Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge.
A series of enzymes catalyze the reaction X to Y to Z to A. Product A binds to an enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme
When Product A binds to X, the process is called...
Both an allosteric and feedback inhibitor.
Which of the following terms best describes the forward reaction in Figure 8.1?
Exergonic (?G<0)
Which of the following represents the activation energy required for non catalyzed reaction in Figure 8.1?
C
An aldose and ketose with the same chemical formula would be referred to as _____________ isomers.
structural isomers
(example image of a structural isomer)
cis-trans isomers (geometric isomers)
carbons have covalent bonds to the same atoms, but these atoms differ in their spatial arrangements due to the inflexibility of double bonds
Enantiomers
isomers that are mirror images of each other
A Benedict's/Barfoed's Test will indicate the presence of
Carbohydrates (monosaccharides)(glucouse)
A IKI test will indicate the presence of
Carbohydrates (polysaccharides) (starch)
A Ninhydrin Test will indicate the presence of
Proteins (amino acids)
A Biruet test will indicate the presence of
Proteins (polypeptide bonds)
A Sudan III/IV test will indicate the presence of
Lipids
What is dehydration synthesis?
Dehydration synthesis is the process of joining two molecules, or compounds, together following the removal of water.
What is hydrolysis?
the chemical breakdown of a compound due to reaction with water.
When a polypeptide is heated, and the secondary structure is denatured, which types of bonds are affected?
Hydrogen Bonds
(Polypeptide Bonds appear in the Quaternary Structure)
In cell fractionation, the primary factor that determines whether a specific cellular component ends up in the supernatant or the pellet is the...
The size and weight of the component.
Cell size is limited by
surface area to volume ratios
Prokaryotes are classified as belonging to two different domains. What are the domains?
Bacteria and Archaea
What is the function of the nuclear pore complex found in eukaryotes?
It regulates the movement of proteins and RNAs into and out of the nucleus.
Large numbers of proteins generated in cells would likely have a high abundance of
ribosomes
A cell with an extensive area of smooth endoplasmic reticulum is specialized to _____.
synthesize large quantities of lipids.
A cell with a predominance of free ribosomes is most likely
Primarily producing proteins in the cytosol.
Rank the following one-base point mutations (from most likely to least likely) with respect to their likelihood of affecting the structure of the corresponding polypeptide.
1. insertion mutation deep within an intron.
2. substitution mutation at the third
4, 3, 2, 1
When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes
reduced
Substrate-level phosphorylation accounts for approximately how much of the ATP formed by the reactions of glycolysis?
100%
Starting with one molecule of glucose, the energy-containing products of glycolysis are
2 NADH, 2 Pyruvate, 2 ATP
Where are the proteins of the electron transport chain located?
Mitochondrial inner membrane.
Approximately how many molecules to ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration?
30+
The alternative pathways of photosynthesis using the C4 or CAM systems are said to be compromises. Why?
Both minimize photorespiration but expend more ATP during carbon fixation.
Which of the following does NOT occur in the Calvin Cycle?
Release Oxygen
Where does the Calvin cycle take place?
stroma
The electrons of photosystem II are excited and transferred to electron carriers. From which molecule or structure do the photosystem II replacement electrons come?
Stroma of the chloroplasts.
What is primarily function of the Calvin Cycle?
Synthesize simple sugars from carbon dioxide.
How many rotations of the Krebs cycle are required to produce two molecules of G3P?
6
Which of the following types of molecules are the structural components of the cell membrane?
Phospholipids and Proteins
In order for a protein to be an integral membrane protein it would have to be
Amphipathic, with at least one hydrophobic end.
integral proteins
penetrate the hydrophobic interior of the lipid bilayer
peripheral proteins
The proteins of a membrane that are not embedded in the lipid bilayer; they are appendages loosely bound to the surface of the membrane.
Which of the following is a reasonable explanation for why unsaturated fatty acids help keep any membrane more fluid at lower temperature?
The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.
When a cell is in equilibrium with its environment, which of the following occurs for substances that can diffuse through the cell?
there is no random movement of substances into or out of the cell.
The difference between pinocytosis and receptor-mediated endocytosis is that ______________.
Pinocytosis is non selective in the molecules that it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity.
Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using this information, which transport
Facilitated Diffusion.
Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called
cyclins.
cyclic electron flow
uses only photosystem I and produces ATP, but not NADPH
Which is first Photosystem I or II?
Photosystem II is first then Photosystem I.
The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. This results in
A polypeptide missing an amino acid. (since a codon is a group of three nucleotides it won't change the reading frame it will simply erase it from the end.)
Which of the following DNA mutations will be the most likely to be damaging to the protein it specifies.
A base- pair deletion.
Hardy-Weinberg equilibrium
The condition describing a non-evolving population (one that is in genetic equilibrium).
Five Hardy-Weinberg Conditions
#NAME?
Hypertonic
Having a higher concentration of solute in the cell than outside the cell.
Hypotonic
...
Hypertonic
Having a higher concentration of solute in the cell than outside the cell.
Hypotonic
...
The nuclear lamina is an array of filaments on the inner side of the nuclear membrane. If a method were found that could cause the lamina to fall into disarray, what would you expect to be the most likely consequence?
A change in the shape of the nucleus
Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large, complex, undigested lipids. Which cellular organelle must be involved in this condition?
The lysosome
The liver is involved in detoxification of many poisons and drugs. Which of the following structures is primarily involved in this process, and therefore, abundant in liver cells?
Smooth E.R.
What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell?
ER - cis Golgi - trans Golgi - vesicles that fuse with the plasma membrane.
How do we differentiate between peroxisomes and lysosomes?
Peroxisomes break down smaller types of items like fatty acids.
Cells require which of the following to form cilia or flagella?
Tubulin
What kinds of molecules pass through a cell membrane most easily?
small and hydrophobic
Researchers tried to explain how vesicular transport occurs in cells by attempting to assemble the transport components. They set up microtubular tracks along which vesicles could be transported, and they added vesicles and ATP (because they knew the tran
Motor Proteins
Cytochalasin D is a drug that prevents actin polymerization. A cell treated with cytochalasin D will still be able to
Move vesicles within a cell.
Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through
Gap Junctions
What are gap junctions (communicating junctions)?
Animal cell junctions that function similarly to plasmodesmata in plant cells
- they are membrane-lined channels that join a cell to an adjacent cell
- Allows for ions, sugars, amino acids and other small molecules to pass between cells
What are tight junctions
Membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid
What are desomosomes?
prevent cells from separating during contraction
Where would you expect to tight junctions?
In the epithelium of an animal's stomach
Why is ATP an important molecule in metabolism?
A) Its hydrolysis provides an input of free energy for exergonic reactions.
B) It provides energy coupling between exergonic and endergonic reactions.
C) Its terminal phosphate group contains a strong covale
B) It provides energy coupling between exergonic and endergonic reactions.
Substrate-level phosphorylation accounts for what percentage of the ATP formed by the electron transport chain?
0% (ATP in the ETC comes from oxidative phosphorylation and moving hydrogen ions across a gradient and then bringing them back in.)
Substrate-level phosphorylation accounts for what percentage of the ATP formed by glycolysis?
100% (This is how ATP is made in glycolysis and in the Kreb's cycle.)
In addition to ATP, what are the end products of glycolysis?
NADH and Pyruvate (2 pyruvate)
Most CO2 from catabolism is released during
Citric Acid Cycle (Krebs Cycle)
Chemiosmotic ATP synthesis occurs in
All respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors.
The final electron acceptor of the Electron transport chain that functions in aerobic oxidative phosphorylation is...
Oxygen
Which of the following occurs in the cytosol of a eukaryotic cell?
Glycolysis and Fermentation
For each mole of glucose (C6H12O6) oxidized by cellular respiration, how many moles of CO2 are released in the citric acid cycle (see the accompanying figure)?
6
Starting with citrate, which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle?
3 ATP, 6 CO2, 9 NADH, and 3 FADH2
Starting with one molecule of isocitrate and ending with fumarate, what is the maximum number of ATP molecules that could be made through substrate-level phosphorylation?
A) 1
B) 2
C) 11
D) 12
E) 24
1
A facultatively anaerobic bacterium survives without the enzymes for Krebs or ETC by using ________.
Fermentation
Which metabolic pathway is common to both cellular respiration and fermentation?
Glycolysis
What happens if an obligate aerobe organism ingests a poison that interferes with the integral proteins in the ETC?
The organism will die.
Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
ATP and NADPH
How many turns of the Calvin cycle will generate 2 molcules of G3P?
6 (1 molecule of G3P generates the Calvin cycle 3 times
Which of the following sequences correctly represents the flow of Electrons during photosynthesis?
H2O - NADPH - Calvin Cycle
The reactions that produce molecular oxygen (O2) take place in __________.
The light reactions alone.
Generation of proton gradients across membranes occurs during
Both photosynthesis and cell respiration.
The splitting of carbon dioxide to form oxygen gas and carbon compounds occurs during
Neither photosynthesis nor cellular respiration.
In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during ______________.
Both photosynthesis and cell respiration
What is the primary function of the Calvin cycle?
synthesize simple sugars from carbon dioxide
Reactions that require CO2 take place in
the Calvin cycle [light-independent reactions] alone
Photorespiration occurs when rubisco reacts RuBP with
O2 (oxygen)
How is photosynthesis similar in C4 plants and CAM plants?
In both cases, rubisco is not used to fix carbon initially.
Diffusion ____________.
Is a passive process in which molecules more from a region of higher concentration to a region of lower concentration.
Which of the following is a type of local signaling in which a cell secretes a signal molecule that affects neighboring cells?
Paracrine Signaling
Figure 10.1 shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different?
Other pigments absorb light in addition to chlorophyll a.
One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, and then activating relay proteins. Which type does this?
Receptor Tyrosine Kinase
A drug designed to inhibit the response of cells to testetrone would most likely result in ______________.
A decrease in transcriptional activity of certain genes.
Hormones are chemical substances produced in one organ that are released into the bloodstream and affect the function of a target organ. For the target organ to respond to a particular hormone, it must _____.
Have receptors that recognize and bind the hormone molecule.
A farmer uses triazine herbicide to control pigweed in his field. For the first few years, the triazine works well and almost all the pigweed dies; but after several years, the farmer sees ore and more pigweed. Which of these explanations best explains wh
Triazine - resistant weeds were more likely to survive and reproduce.
After the drought of 1977, researchers hypothesized that on the Gal�pagos island Daphne Major, medium ground finches with large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cisto
Evolution of smaller pointier beaks over time, until all birds have relatively small, pointy beaks.
Given a population that contains genetic variation, what is the correct sequence of the following events, under the influence of natural selection?
1. Well-adapted individuals leave more offspring than do poorly adapted individuals.
2. A change occurs in
2 - 4 - 1 -3
You sample a population of butterflies and find that 56% are heterozygous at a particular locus. What should be the frequency of the recessive allele in this population?
Allele frequency cannot be determined from this information.
According to the concept of punctuated equilibrium,
A new species accumulates most of its unique features as it comes into existence.
Which of the following would be useful increasing a phylogenetic tree?
I) Morphological Data from Fossil Species
II) Genetic Sequences from Living Species
III) Behavioral Data from Living Species
I, II, and III (ALL THREE)
Eukaryotes that are not closely related and do not share many anatomical similarities can still be placed together on the same phylogenetic tree by comparing their ___________________.
Homologous Gene that are poorly conserved.
The heterokarotic phase of a fungal life cycle is
A stage in which hyphae contain two genetically different haploid nuclei.
The most direct ancestors of land plants were probably________________.
Green Algae
Which of these are spore- producing structures?
sporophyte (capsule) of a moss
How could you determine if a plant is heterosporous?
Male and Female reproductive structures are located on separate plants.
Conifers and pines both have needlelike leaves, with the adaptive advantage of _____.
Deceased surface area, reducing water loss.
Transpiration in plants requires _______________.
I) Adhesion of water molecules to cellulose.
II) Cohesion between water molecules.
III) Evaporation of water molecules.
IV) Active Transport through xylem cells.
V) Transpiration through tracheids
I, II, III, and V
Which of the following flower parts develops into the the pulp of a fleshy fruit.
Ovary (Ovule is the seed.)
Ignoring all other factors, what kind of day would result in the fastest delivery of water and minerals to the leaves of a tree?
cool, humid day
Plant hormones___________________.
Affect only the cells with the appropriate receptor.
Which of the following statements is true?
Arthropods have an open circulatory system, while annelids have a closed circulatory system.
You find a wormlike, soft-bodied adult animal in a mud flat. It is bilaterally symmetrical, is segmented, has a true coelom, and has a complete digestive tract. Based on these characteristics, what phylum does the animal represent?
Annelida
Five conditions for Hardy-Weinberg Equilibrium
1. No mutations
2. Random mating
3. No natural selection
4. Extremely large population size
5. No gene flow
When a cell in S phase is fused with a cell in G1, __________.
DNA synthesis begins immediately in the original G1 nucleus.
In Labrador retrievers, a dog that has the genotype BBee, where BB produces black-pigmented fur and ee produces yellow-pigmented fur, would have __________ fur and would exhibit __________.
Yellow; Epistasis
(In epistasis (from the Greek for "standing upon"), the phenotypic expression of a gene at one locus alters the expression of a gene at a second locus. But if the Lab is homozygous recessive for the second locus (ee), then the coat is yellow, regardless of the genotype at the black/brown locus (so-called golden Labs). In this case, the gene for pigment deposition (E/e) is said to be epistatic to the gene that codes for black or brown pigment (B/b). )
The effect of the environment on a phenotype is referred to as __________.
Multi-factorial. (Generally, the phenotypic range is broadest for polygenic characters. Environment contributes to the quantitative nature of these characters, as we have seen in the continuous variation of skin color. Geneticists refer to such characters as multifactorial, meaning that many factors, both genetic and environmental, collectively influence phenotype.)
Pleiotropic
A single gene determines more than one phenotype for an organism.
Which choice below is a basic difference between Mendel's particulate hypothesis and the hypothesis of blending inheritance?
The blending inheritance hypothesis, but not the particulate hypothesis, maintained that after a mating, the genetic material provided by each of the two parents is mixed in the offspring, losing its individual identity.
Mendel's law of segregation states that __________.
The two alleles for a heritable character segregate (separate from each other) during gamete formation and end up in different gametes
Which of the following attributes of DNA is most crucial to its accurate duplication? (Concept 16.2)
Its specific base pairing through hydrogen bonds. (Correct. Hydrogen bonding makes it easy to separate the two strands. Specific complementary base pairing ensures that an accurate strand will be constructed on each template strand.)
During the replication of DNA, __________.
Both strands of a molecule act as templates.(Correct. When a cell copies a DNA molecule, each strand serves as a template for ordering nucleotides into a new complementary strand.)
The experiments of Meselson and Stahl showed that DNA __________.
Replicates in a semiconservative fashion.(Correct. In the semiconservative model of DNA replication, the two strands of the parental molecule separate. Each functions as a template for the synthesis of a new complementary strand.)
DNA polymerase adds nucleotides to the __________ of the leading strands, and to the __________ of the lagging strands (Okazaki fragments).
3? end ... 3? end (DNA POLYMERASE CAN ONLY START ADDING FROM THE 5' END MEANING THAT IT IS ADDING TO THE 3' END.)(Correct. Although the leading strand and lagging strand are synthesized in opposing directions with respect to the movement of the replication fork, the DNA polymerase enzyme can only add nucleotides to the 3? end of a growing DNA strand.)
NOTE TO SELF: WHAT ARE THE ROLES OF DNA POLYMERASE 3, DNA POLYMERASE 1, and DNA LIGASE?
The role of DNA Polymerase 3 is to add free floating nucleotides (from 5' to 3') to the 3' end of a DNA strand after primase has been added. The role of DNA Polymerase 1 is to go to the Okazaki fragments (removes the initial RNA primer) and fills in that space with DNA. DNA Ligase is meant to go back and unite (connect) the fragments to the rest of the DNA strand.
Unlike prokaryotic DNA replication, replication of eukaryotic chromosomes __________.
Cannot be completed by DNA polymerase.(Correct. This is the case because eukaryotic chromosomes are linear, and DNA polymerase cannot replicate the extreme 3? end of the template strands.)
Telomeres __________. (the ends of a chromosome)
Get shorter with each round of DNA replication.(Correct. However, the enzyme telomerase, which is not present in most cells of multicellular organisms, can lengthen the telomeres.)
Telomerase __________.
An enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells.
In a comparison between asexually reproducing bacteria and sexually reproducing multicellular eukaryotes, uncorrected errors in replication are more likely to be transmitted to subsequent generations in bacteria than in multicellular eukaryotes. Which of
Because they are asexual and single-celled, all uncorrected errors of replication in bacteria are transmitted to subsequent generations. Multicellular eukaryotes typically reproduce sexually, so uncorrected errors are transmitted only if they occur in germ cells that meiotically divide to produce gametes.(
In the "beads on a string" structure of unfolded chromatin, the "beads" are __________.
Nucleosomes.(Correct. Nucleosomes are complexes of DNA wrapped around eight histone molecules.)
What is euchromatin?
less condensed, transcriptionally active, sterically accessible form of DNA
--EUchromatin is TRUly transcribed.--
What is heterochromatin?
condensed, transcriptionally inactive, sterically inaccessible form of DNA
--HeteroChromatin is Highly Condensed.--
Euchromatin vs Heterochromatin
Euchromatin - available for transcription; naked DNA
Heterochromatin - not available for transcription; covered DNA; protein coat
Who formulated the one gene-one enzyme hypothesis?
Beadle and Tatum.(Correct. Restating Beadle and Tatum's idea as one gene-one polypeptide reflects the current idea that each polypeptide is specified by one gene.)
Generally speaking, how many genetic codes are there?
One.(Correct. Although slight variations do exist, the genetic code is essentially universal. Nearly all organisms use the same genetic code to translate mRNA to protein.
The codons AAA, CCC, GGG, and UUU specify the amino acids lysine, proline, glycine, and phenylalanine, respectively. If the base sequence 5?-CCCAAATTTGGG-3? is present in the coding strand of a stretch of DNA, what polypeptide sequence would be encoded by
Proline-Lysine-Phenylalanine-Glycine.(Correct. The sequence of the coding strand of the DNA is equivalent to that of the transcribed mRNA, except that it contains thymine where the mRNA has uracil.)
What catalyzes the linkage between ribonucleotides to form RNA during gene expression?
RNA Polymerase.(Correct. The enzyme responsible for transcription is RNA polymerase.)
One strand of a DNA molecule has the following sequence: 3?-AGTACAAACTATCCACCGTC-5?. In order for that strand to be transcribed, there would have to be a specific recognition sequence, called a(n) __________, to the left of the DNA sequence indicated.
Promoter.(TATA box)(Correct. The region of DNA to which RNA polymerase attaches and initiates transcription is the promoter, which typically extends several dozen nucleotides "upstream" from the transcription start point.)
In transcription, __________.
a)the RNA nucleotides used are produced by the cell.
b)the promoter region acts as an initial binding site for RNA polymerase.
c)only one of the DNA strands is used as the template.
d)All of the answer choices are correct.
All of the answer choices are correct..(Correct. After binding to the promoter, the RNA polymerase initiates RNA synthesis at the start point on the template strand. Nucleotides from a pool within the cell are used to elongate the growing strand of RNA. Nucleotide sequences within the promoter determine in which direction the polymerase faces and which strand is used as the template.)
Two different proteins with mostly different structures are translated from two different mRNAs. These mRNAs, however, were transcribed from the same gene. Which mechanism could best account for this?
Exons from the same gene could be spliced in different ways to make different mRNAs.
What is a key difference between eukaryotic and prokaryotic gene expression?
In prokaryotic cells, the RNA transcript is immediately available as mRNA without processing.(Correct. Because it lacks a nucleus, a prokaryote can simultaneously transcribe and translate the same gene.)
The function of tRNA during protein synthesis is to __________.
Deliver amino acids to their proper site during protein synthesis.(Correct. Each tRNA molecule is used repeatedly, picking up its designated amino acid in the cytosol, depositing this cargo at the ribosome, and leaving the ribosome to pick up another load.)
The function of tRNA during protein synthesis is to __________.32
Deliver amino acids to their proper site during protein synthesis.(Correct. Each tRNA molecule is used repeatedly, picking up its designated amino acid in the cytosol, depositing this cargo at the ribosome, and leaving the ribosome to pick up another load.)
The P site of a ribosome does which of the following?
It holds the tRNA carrying the growing polypeptide chain.(Correct. The P site (peptidyl-tRNA site) holds the tRNA carrying the growing polypeptide chain, whereas the A site (aminoacyl-tRNA site) holds the tRNA carrying the next amino acid to be added to the chain.)
Which process does NOT occur during translation?
a) cleavage of a polypeptide into two or more chains.
b)removal of introns and splicing of exons.
c)formation of a polysome that allows simultaneous formation of many polypeptides from one mRNA transcript.
Cleavage of a polypeptide into two or more chains.(Correct. Once a polypeptide has been formed during translation, it can undergo post-translational modifications.)
Polysomes may be defined as __________.
Groups of ribosomes translating the same mRNA.(Correct. Polysomes are strings of ribosomes reading the same mRNA.)
Cells are able to distinguish proteins destined for secretion or for segregation to specific intracellular compartments from those that will remain in the cytoplasm because __________.
Some proteins, as they begin to be synthesized, contain a signal region that causes the ribosome with its growing polypeptide to attach to the ER and translocate the polypeptide into the lumen (space) of the ER.(Correct. The synthesis of all proteins begins in the cytosol. Only if the polypeptides are destined for the endomembrane system or for secretion will they contain a signal peptide, which targets the protein to the endoplasmic reticulum.)
What is their proper sequence for these steps?
1. translation
2. RNA processing
3. transcription
4. modification of protein
3, 2, 1, 4
The mRNA codons 5?-CAA-3? or 5?-CAG-3? are translated as the amino acid glutamine by __________.
The same tRNA with the anticodon 3?-GUU-5?.(Correct. Because a tRNA anticodon with U at its 5? end can pair with either A or G in the third position (at the 3? end) of an mRNA codon, the same tRNA can correctly translate both of these codons as glutamine.)
Which statement regarding the structure and function of tRNA is false?
Although each tRNA consists of a relatively short, single RNA strand, this single strand can achieve a three-dimensional structure by folding back upon itself and forming covalent bonds between complementary bases.(Correct. This statement is false. Complementary stretches of nucleotides pair by hydrogen bonds, allowing the single strand of RNA to take on a three-dimensional structure.)
This chapter contains a lengthy discussion of the trp operon involved in regulating the synthesis of tryptophan. In the case of E. coli, the bacterium may need to synthesize tryptophan, or its host, a human, may supply all the tryptophan it needs. Why do
It is one of the 20 amino acids used by all organisms to synthesize proteins.
In prokaryotic genomes, groups of functionally related genes along with their promoters and operators are found together in __________.
An operon.(Correct. Putting these related sequences together helps prokaryotes keep related genes under coordinate control.)
A bacterium can make the amino acid glycine or absorb it from its surroundings. A biochemist finds that glycine binds to a repressor protein and causes the repressor to bind to the bacterial chromosome, turning off an operon. If it is like other similar o
Cessation of the synthesis of glycine.(There is no need to produce glycine if it's already in the environment.)
In general, operons that encode the enzymes of a biosynthetic (anabolic) pathway (such as the trp operon) are __________, and those encoding the enzymes of a catabolic pathway (such as the lac operon) are __________.
Repressible ... Inducible.(Correct. Anabolic pathways are generally on unless their product is not needed. Catabolic pathways need to adjust to the available substrate.)
In an inducible operon, the inducer is often the __________ in the pathway being regulated; the inducer binds to the __________, which then becomes __________.
Substrate ... Repressor ... Inactive
You have inserted the gene for human growth factor into the E. coli lactose operon, replacing the structural genes with the gene for human growth factor. What substance must you add to your culture of bacteria to cause them to produce human growth factor
Allolactose.(Correct. Allolactose will bind to the repressor protein, inactivating it, and allowing transcription of the genes in the operon, including human growth factor.)
Both repressible and inducible operons control gene expression at the level of __________. (Concept 18.1)
Transcription.(Correct. The repressors that attach to operators act to block transcription.)
The control of gene expression is more complex in multicellular eukaryotes than in prokaryotes because __________.
In a multicellular eukaryote, different cells are specialized for different functions.(Correct. Also, eukaryotic cells are more complex than prokaryotic cells.)
In some cases, DNA methylation and removal of acetyl groups from histones (i.e., deacetylation) combine to __________.
Silence certain genes.(Correct. Both DNA methylation and histone deacetylation tend to repress transcription.)
An enhacer is ______________________.
Is a nucleotide sequence in the DNA.
In eukaryotes, DNA packing seems to affect gene expression primarily by __________.
Controlling access to DNA.(Correct. For example, the genes of tightly packed heterochromatin are usually not transcribed, presumably because RNA polymerase and other necessary proteins can't make contact with the DNA.)
A scientist clones a regulatory gene that is involved in controlling the expression of other genes, and discovers that the regulatory gene encodes an enzyme that acetylates histones. It is likely that this enzyme regulates gene expression by __________.
Causing looser packing of the chromatin at the target gene, thereby enhancing transcription.(Correct. Acetylation promotes a more open chromatin structure, making DNA more accessible for transcription.)
In a eukaryote, transcription factors called activators may stimulate gene expression by binding to DNA sites called __________.
Enhancers.(Correct. Enhancers are sites within the DNA where activators bind, increasing the rate of transcription.)
Enhancers __________.
a)are found in eukaryotic genomes
b)may be located upstream or downstream from the genes they regulate
c)may be located thousands of base pairs away from the promoter
d)increase the rate of transcription
e)All of the listed responses
All of the listed responses are correct.(Correct. Enhancers increase the rate of transcription and may be located thousands of base pairs away from the promoter, either upstream or downstream.)
Operons are ________________.
Only found in Prokayotes.
Dioxin, produced as a by-product of various industrial chemical processes, is suspected of causing cancer and birth defects in animals and humans. It apparently acts by entering cells and binding to specific proteins, which then enter the nucleus and alte
Steroid hormones.(Correct. Steroid hormones enter cells, bind to specific receptors, and enter the nucleus to affect transcription.)
What is the evolutionary significance of alternative RNA splicing?
It expands the number of proteins that can be coded for by one gene, increasing an organism's ability to produce novel proteins.(Correct. Some genes could produce thousands of different proteins from a primary transcript. In most cases, only a few of the possibilities are actually produced. However, different splicing could give rise to novel proteins, some of which could be advantageous.)
What is the role of proteasomes?
They are giant protein complexes that recognize ubiquitin and degrade the tagged proteins. (Correct. Mutations that make cell cycle proteins impervious to proteasome degradation can lead to cancer.)(Proteasomes break down proteins, not RNAs.)
What determines how long a particular mRNA molecule will persist in a eukaryotic cell?
Nucleotide sequences in the 3? untranslated region of the mRNA.(Correct. Nucleotide sequences in the untranslated region at the 3? end of the molecule seem to be crucial in determining how long-lived a particular mRNA is.)
Which of the following statements is NOT associated with epigenetic inheritance?
Chemical Mutagens.(Correct. By definition, chemical mutagens are chemical agents that can cause an inheritable change in the nucleotide sequence of an organism's DNA. All the other answers are examples of changes made to DNA other than the nucleotide sequence that can affect gene expression and are inheritable.)
A high rate of gene transcription in eukaryotic cells is usually dependent on __________.
a) the binding of general transcription factors to the TATA box within the promoter of a gene.
b) the coordinated control of genes within operons.
c) specific bindin
The third and fourth listed responses are correct.(Correct. Specific binding of activator molecules to enhancers and the protein-protein interactions that are promoted by the activation domains of activator proteins equate to elevated rates of gene transcription.)
Which of the following best depicts coordinate control of genes in eukaryotes?
a) Different genes for proteins involved in a specific metabolic process typically share the same enhancer regions.
b) Although a group of genes involved in a related metabolic
The second and third listed responses are correct.(Correct. Coordinate control of genes involved in a specific cellular process but scattered over different chromosomes is facilitated by: 1) a specific combination of control elements and activator molecules being shared by every gene of a dispersed group and 2) the congregation of the dispersed genes on different chromosomes into transcription factories within the nucleus.)
Although the number of genes in the human genome is surprisingly low compared to less complex organisms, the number of possible products from those genes is greatly amplified by __________.
Alternate arrangements of exons from a primary transcript.(Correct. It is now thought that 75 to 100% of genes with multiple exons in the human genome undergo some degree of alternate splicing, thereby greatly increasing the number of possible human proteins and helping to account for the complex morphology in the human form.)
Which of the following best describes the current understanding of the makeup of the human genome?
Genes for noncoding RNA make up the majority of meaningful genetic information in the human genome.
The discovery of many noncoding RNAs is causing scientists to revise the long-held view that __________.
a) there are only three types of RNA�tRNA, rRNA, and mRNA
b) only DNA that codes for protein, tRNA, and rRNA is transcribed
c) all genes code for prot
All of the listed responses are correct.(Correct. All of the listed "facts" have been challenged by the discovery of a number of types of RNA that do not code for protein.)
MicroRNAs and small interfering RNAs both function similarly in "silencing" genes. What are two ways in which they may act?
Promote the degradation of mRNA and bind to complementary mRNA sequences to prevent translation.(Correct. miRNAs and siRNAs act in both of these ways to prevent a transcribed gene from being translated into protein. In addition to their normal roles in cells, researchers see these RNAs as useful tools in studying the function of genes by being able to silence them.)
It is hypothesized that an increase in the number and diversity of noncoding RNA (ncRNA) in the genomes of species has driven the evolution of morphological complexity by way of their influence on gene regulation. Which of the following accurately represe
All of the listed responses are correct.(Correct. Recent findings suggest that ncRNAs play a vital role in most aspects of gene regulation in eukaryotic organisms and, in doing so, may have provided the basis for the evolution of a higher degree of complexity of form.)
Specific cells that appear undifferentiated under the microscope but are already fated to become muscle cells are called __________.
Myoblasts.(Myosins are the proteins within muscle cells.)
MyoD promotes muscle cell development by __________.
Turning on the expression of multiple muscle-related genes.(Correct. MyoD is a protein that acts as a transcription factor to turn on many genes involved in muscle cell development, including the gene that codes for MyoD.)
Cytoplasmic determinants __________.
Are coded for by maternal genes.
Cells can influence each other's development by a process known as __________.
Induction.(Correct. Induction occurs when cell signals from one cell affect the development of nearby cells.)
Instead of developing a head and a tail, an abnormal Drosophila embryo develops two tails. This is most likely due to __________.
A mutation in a maternal effect gene.(Correct. Some maternal effect genes provide positional information in the developing embryo. Mutations in these genes can cause abnormal development.)
Cell differentiation is first observable when __________.
mRNAs for tissue-specific proteins appear in a cell.(Correct. Even before a cell's structure begins to change, differentiation is heralded by the appearance of these mRNAs in the cell.)
What gene has been called the "guardian angel of the genome"?
The p53 gene.(Correct. The p53 gene can activate several genes involved in DNA repair, halting of the cell cycle, or initiation of apoptosis.)
What two genes are often mutated in colon cancer?
a. BRCA1 and BRCA2
b. ras and p53
c. APC and myoD
d. ras and myoD
e. p21 and p53
b. ras and p53.
Why is cancer more prevalent in older people?
a. Cancer is caused by viruses, and older people are more susceptible to viral infections.
b. Cancer lies dormant for many years before causing problems.
c. Most cancers are inherited as a recessive allele, so
c. Most cancers are inherited as a recessive allele, so it takes time for the allele to be expressed.
In what way can cancer be hereditary?
a. Proto-oncogenes can be inherited, giving the person a predisposition to developing cancer.
b. Tumor-suppressor genes can be inherited, giving the person a predisposition to developing cancer.
c. One or two of sever
c. One or two of several mutations necessary for full cancer development can be inherited, giving a person a predisposition to developing cancer.
The BRCA1 and BRCA2 genes are thought to be what type of genes?
Tumor-suppressor genes
Which of the following accurately characterizes our current understanding of cancer development?
In order for a cell to become fully cancerous, it typically must have at least one active oncogene and the mutation or loss of several tumor-suppressor genes.(Correct. Our current understanding suggests that several key changes must occur in the DNA of a cell before it can become cancerous. These changes are brought about by mutations to convert a proto-oncogene to an active oncogene and the loss of tumor-suppressing proteins such as p53.)
Which of the following catalyzes the linkage between ribonucleotides to form RNA during gene expression?
RNA polymerase catalyzes the linkage between ribonucleotides to form RNA during gene expression.
Gene expression is __________.
The process by which DNA directs the synthesis of proteins.
The TATA box is a __________ that allows for the binding of __________ and __________.
Eukaryotic promoter, Transcription factors, RNA polymerase II.
Polysomes may be defined as __________.
groups of ribosomes
In eukaryotic cells, a __________ by a __________ targets a growing peptide to the endoplasmic reticulum.
Signal peptide; Signal-recognition particle
The "triplet code" refers to the fact that _________.
The "triplet code" refers to the fact that three nucleotides code for a single amino acid.
Which of the following best describes the arrangement of genetic information in a DNA molecule?
The three-nucleotide words of a gene are arranged in a nonoverlapping series on the DNA template strand.
Stop codons are unique because they __________.
do not code for amino acids that allow a releasing factor to bind to the A site of the ribosome.
By bombarding the fungus Neurospora crassa with X-rays, Beadle and Tatum were able to study __________ and characterize enzymes in a __________.
Nutritional mutants; Biochemical pathway
MicroRNAs binding to complementary sequences on an mRNA __________.
results in either blocking translation or degrading the targeted mRNA
Cell type-specific transcription is accomplished __________.
by specific enhancer control elements interacting with cell type-specific transcription factors
In the trp (tryptophan) operon, the __________ binds to the product of the trp operon synthesis pathway, called __________, forming the __________.
repressor protein; tryptophan; active repressor
Gene expression in bacteria is regulated primarily by __________.
controlling the transcription of genes into mRNA
In Drosophila development, the anterior-posterior axis of the embryo is determined by __________.
egg-polarity genes
What is a maternal effect gene?
A gene that, when mutant in the mother, results in a mutant phenotype in the offspring, regardless of the offspring's own genotype.
Although the number of genes in the human genome is surprisingly low compared to less complex organisms, the number of possible products from those genes is greatly amplified by __________.
alternate arrangements of exons from a primary transcript
__________ arose very early in hominid evolution; __________ evolved more recently.
Upright Posture; Very Large Brains.
The adaptation that freed vertebrates from water for reproduction and allowed them to radiate into diverse terrestrial environments was the __________.
amniotic egg
Where are the proteins of the electron transport chain located?
Mitochondrial Inner Membrane
During chemiosmosis,
ATP is synthesized when H+ ions move through a channel in ATP synthase.
________ are early vertebrates that lacked jaws, had large eyes, and had mineralized dental tissues.
Conodonts
The fact that tunicates have only 9 sets of Hox genes while lancelets and all other chordates have 13 sets of Hox genes indicates that ____________.
The tunicate larva is using a different set of genetic controls than that of other chordates.
Sharks and rays belong to the clade ________.
Chondrichthyes
Derived amniote characteristics include all of the following except ___________.
a)the yolk sac
b)the amnion
c)the allantois
d)embryonic membranes
e)the chorion
d) Embryonic Membranes (Amniotes are named for the major derived character of the clade, the amniotic egg, which contains four specialized membranes: the amnion, the chorion, the yolk sac, and the allantois. Called extraembryonic membranes because they are not part of the body of the embryo itself, these membranes develop from tissue layers that grow out from the embryo. )
Starting with a fertilized egg, a series of three cell divisions would produce an early embryo with how many cells?
8 cells
Density-dependent inhibition is explained by which of the following?
As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing.
If there are 40 centromeres in a cell at anaphase of mitosis, how many chromosomes will be found in each daughter cell following cytokinesis?
20
Meiosis II is similar to mitosis in that
sister chromatids separate during anaphase
Where does the ETC occur?
inner membrane of mitochondria
where does the ETC occur in prokaryotes?
In the cell membrane.
In human mitosis (2n=46) there are ____________ chromosomes present and __________ sister chromatids present after anaphase has finished.
92; 0
In human meiosis there are ___________ chromosomes present and __________ sister chromatids present after anaphase II has finished.
46;0
In a human karyotype, chromosomes are arranged in 23 pairs. if we choose one of these pairs, such as pair 14, which of the following do the two chromosomes of the pair have in common?
Length, centromere position, staining pattern, and traits coded for by their genes.
Chromatids are separated from each other.
The statement is true for mitosis and meiosis II.
The following question refers to the essential steps in meiosis described below.
1. Formation of four new nuclei, each with half the chromosomes present in the parental nucleus
2. Alignment of tetrads at the metaphase plate
3. Separation of sister chromat
B. 3
Independent assortment of chromosomes is a result of
The random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I.
Law of Segregation
Mendel's law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete.
Refer to the following information answer the question below. Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time
Epistasis
In transcription, the promoter is located
Upstream to the gene of interest on the 3' antisense strand.
In translation, the guanine cap helps the small ribosomal subunit to bind to mRNA, but the charged tRNA can't bind to mRNA until_______________.
It attaches to an AUG codon.
In the process of transcription, _______________________.
RNA is synthesized.
Which of the following can be duplicated in a genome?
a) Only entire sets of chromosomes
b) Only entire chromosomes
c) Only DNA sequences
d) All of the above.
d) All of the above.
Put the following events of elongation in protkaryotic translation in chronological order.
1. Binding of mRNA with small ribosomal unit.
2. Recognition of initiation codon.
3. Complementary base pairing between initiator codon and anticodon of initiator t
1, 2, 3, 5, 4
Gene expression is often assayed by measuring the level of mRNA produced from a gene. If one is interested in knowing the amount of a final active gene product, a potential problem of this method is that it ignores the possibility of ____________.
Translational control