Sodium ions are more concentrated in the extracellular fluid than in the intracellular fluid. This is an example of
chemical disequilibrium.
Oxidative phosphorylation occurs ________; the beneficial end product is ________.
in the mitochondria due to the electron transport system, ATP
Caveolae and clathrin-coated pits are both used in
endocytosis
If the enzyme RNA polymerase was completely inhibited within a cell, it could not
form proteins
The resting membrane potential in a typical nerve cell is approximately
-70 mV.
Pinocytosis and potocytosis are types of
endocytosis
Transcription of the DNA triplet sequence CAT will bind to the tRNA bearing
GUA
In the absence of a signal sequence, a newly synthesized protein localizes to the
cytoplasm
Which of the following is a way for solutes in an aqueous solution to move from an area of high solute concentration to an area of low solute concentration?
only facilitated diffusion
The general term that describes energy stored in chemical bonds is
potential energy
Changes in environmental pH or temperature will cause the reaction rate for an enzyme to
either increase or decrease depending upon enzyme properties.
Saturation occurs when
a group of carrier proteins is operating at its maximum rate.
Organic molecules that act as receptors/carriers for the cleaved portion of the substrate are
coenzymes
Which property of diffusion best helps explain the necessity of the circulatory system in multicellular organisms?
Diffusion is rapid over short distances but much slower over long distances.
If a 10% sucrose solution is separated from a 20% sucrose solution by a membrane impermeable to sucrose, in which direction will net movement of water occur?
from the 10% sucrose solution to the 20% sucrose solution only
Which of these results in a REDUCED molecule?
gain of electrons
The addition of a phosphate group to a substrate is called ________. The enzyme that catalyzes this reaction is referred to as a ________.
phosphorylation; kinase
The tRNA molecule contains the three-base sequence called the
anticodon
An exergonic chemical reaction
releases energy as the reaction progresses.
A reversible reaction is one where
there are small changes in the net free energy from substrate to product.
The term cellular (metabolic) energy indicates any biological process requiring
ATP
Which of the following is a key intermediate of glucose catabolism to the citric acid cycle?
pyruvate
The protein in the mitochondria that captures the kinetic energy of moving H+ ions and converts it to the stored energy of ATP is called
ATP synthase
The rate of product formation by an enzyme-catalyzed reaction would be increased by
adding more substrate molecules.
Compartmentation refers to
grouping related enzymes into specific organelles.
The net energy yield for the anaerobic metabolism of one glucose molecule is
2 ATP and 0 NADH.
Enzymes are often useful as diagnostic tools. How?
Damaged cells release enzymes into the blood that can be detected.
During starvation, steroid hormones trigger the transcription of genes for lipid metabolism in their target cells. This would be an example of control by
inducers.
Passive transport refers to a process that requires
no cellular energy.
An enzyme that adds or subtracts water molecules is a
hydrolase
When a neuron changes its ion permeability from the resting state,
only a variety of gated ion channels may open or close and Na+ channels may open, allowing Na+ to enter the cell.
As the charge on the membrane of a typical neuron approaches 0 from -70 mV, the cell is
only depolarizing.
Facilitated diffusion and active transport differ in that
ATP is necessary for active transport, but not for facilitated diffusion.
In the absence of a signal sequence, a newly synthesized protein localizes to the
cytoplasm.
Anions will ________ each other.
repel
Fick's law of diffusion states that the rate of diffusion across a membrane is
proportional to concentration gradient, surface area, and membrane permeability.
Which of the following is a unique characteristic of glucose as a solute in biological systems?
100% of it is absorbed into the cell from the extracellular fluid.
Which of the following molecules can move across the phospholipid bilayer by simple diffusion?
all of the answers are correct
Transcription of the DNA triplet sequence ATC yields
UAG
Substances that readily dissolve in water and do not readily dissolve in lipids are
hydrophilic and lipophobic.
To activate a regulated gene, the formation of mRNA is ________ by the binding of ________ to the promoter.
induced, transcription factors
When a chemical reaction is in equilibrium,
there is no net change in the amount of substrates or products.
When an enzyme is working as fast as it can because its active site is continually refilled with substrate, the condition is referred to as
saturation.
Voltage-gated (voltage-dependent) channels and antiport carriers are both types of
transporters
A cell that is permeable to Solute X is placed into solution containing a higher concentration of X. Diffusion occurs until equilibrium is attained. At this time,
there is no further change in concentration of Solute X.
Water is a polar molecule, yet it easily moves through the nonpolar portions of cell membranes. Which transport process is responsible?
simple diffusion
Which of the following would increase the rate of diffusion across a cell membrane?
a decrease in membrane thickness
Water will always move from ________ areas to ________ areas, if there are no impermeable barriers.
hyposmotic, hyperosmotic
How would the lack of a required cofactor for an enzyme affect that enzyme's function?
The enzyme would not be able to function
A molecule that loses electrons during a reaction is
transcriptions
End-product inhibition describes the process whereby
The process whereby increasing amounts of product reduce activity of the enzyme
Activation energy is
Correct the energy required to bring molecules into a position where they can interact.
After forming a complex with the ribosome, mRNA interacts with a third molecule. This molecule is called
tRNA
If the enzyme RNA polymerase was completely inhibited within a cell, it could not
form proteins
Aerobic metabolism of glucose
requires oxygen and produces more ATP per glucose than anaerobic pathways.
...
...
An enzyme that joins two substrates using energy is a
ligase
Compared to the outside surface, the inside of a resting cell membrane is
negatively charged
When an enzyme is working as fast as it can because its active site is continually refilled with substrate, the condition is referred to as
saturation
In the absence of a signal sequence, a newly synthesized protein localizes to the
cytoplasm
Which of the following is a unique characteristic of glucose as a solute in biological systems?
100% of it is absorbed into the cell from the extracellular fluid.
The ________ of glycogen from many glucose molecules is an ________ reaction.
synthesis, endergonic
The rate of product formation by an enzyme-catalyzed reaction would be increased by
adding more substrate molecules.
Saturation occurs when
a group of carrier proteins is operating at its maximum rate.
Which of the following statements about the Na+/K+ pump is FALSE?
It transports Na+ and K+ in a 1:1 ratio.
Passive transport refers to a process that requires
no cellular energy
In the aerobic metabolism of glucose, ________ acts as the final electron acceptor.
oxygen
Which of the following molecules can move across the phospholipid bilayer by simple diffusion?
All of the answers are correct.
Which can serve as substrates for ATP production?
glucose, amino acids and fatty acids
Why is there a range of 30-32 ATP molecules produced from one glucose molecule?
The NADH molecules produced during glycolysis are in the cytoplasm; occasionally, electrons are carried by the lower energy FADH2 instead of NADH.
An enzyme that transfers chemical groups among substrates is a
transferase.
Once synthesized, the ________ of mRNA are removed through ________, which results in the formation of the coding sequence of a protein.
intron, alternative splicing
An allosteric modulator binds to
a region of the enzyme other than the active site.
An exergonic chemical reaction
releases energy as the reaction progresses.
In an epithelium, the apical membrane is also known as the ________ membrane.
mucosal
Cells normally regulate the rate of an enzymatic reaction by
changing the concentration of an enzyme.
Which body fluid compartment contains higher levels of Na+, Cl-, and HCO3-?
both plasma and interstitial fluid
Which of the following is NOT true of diffusion in the human body?
Smaller molecules take longer to diffuse than larger ones.
Organic molecules that act as receptors/carriers for the cleaved portion of the substrate are
coenzymes
Transcription occurs in the ________ of the cell.
nucleus
The concentration of calcium inside a cell is 0.3%. The concentration of calcium outside the cell is 0.1%. How could the cell transport even more calcium to the inside?
active transport
When you eat a large meal and your body absorbs a lot of glucose and that makes its way to the interstitial fluid before going into the cell. 100% of the glucose should be absorbed into the cell from the interstitial fluid. Why does nearly all of the gluc
It is modified by the cell, so there is still more glucose on the outside of the cell than inside it.
The enzymes that synthesize mRNA from the start codon are called
RNA polymerases.
The template strand of DNA
serves as a guide for mRNA synthesis.
When an enzyme is working as fast as it can because its active site is continually refilled with substrate, the condition is referred to as
saturation
In order to slow generation of product from a particular biochemical pathway within a cell, the intermediates formed by that pathway
accumulate inside the cell.