structure of DNA
DNA is like a ladder or spiral staircase. The outside is made of a sugar-phosphate backbone with alternating sugars and phosphates and the inside "steps" are the nitrogenous bases.
antiparallel strand
-continous grow of DNA molecules work down the line
-depends on overall direction of replication: either top or bottom strand
-5' to 3' direction
-DNA pol III: add nucleotides to free 3' end of RNA primer; works towards replication fork; continously added
DNA replication
process by which DNA is copied in a cell before a cell divides by mitosis, meiosis, or binary fission. initiated in eukaryotic chromosomes at many points
nucleosome
bead-like structure in eukaryotic chromatin, composed of a short length of DNA wrapped around a core of histone proteins
purine
a nitrogenous base that has a double-ring structure; one of the two general categories of nitrogenous bases found in DNA and RNA; either adenine or guanine
pyrimidines
nitrogenous bases that have a single ring of carbon and nitrogen atoms, such as cytosine and thymine
nucleosomes
beads on a string," DNA wound twice around a protein core composed of 8 histone molecules
satelite DNA
once lassified as junk DNA, now classified as highly repetitive DNA, constitutes 5- 45% of the genome.
exons
A coding region of a eukaryotic gene. Exons, which are expressed, are separated from each other by introns.
introns
sequence of DNA that is not involved in coding for a protein
DNA replication in 5'-3" dircetion
process by which DNA is copied in a cell before a cell divides by mitosis, meiosis, or binary fission
helicase
an enzyme that untwists the double helix at the replication forks, separating the two parental strands and making them available as template strands
DNA polymerase
An enzyme that catalyzes the elongation of new DNA at a replication fork by the addition of nucleotides to the existing chain.
RNA primase
synthesis the short RNA molecule that is complementary to the template DNA strad. It provides the 3' hydroxyl group required by DNA polymerase.
DNA ligase
An enzyme that eventually joins the sugar-phosphate backbones of the Okazaki fragments
Okazaki fragments
Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.
transcription 5'-3' direction
(d) nucleotide polymerization occurs only in the 5?-to-3? direction
sense strand
The DNA strand which is always represented on paper. The strand is always the one running from the 5' to the 3'. mRNA is identical to the strand except Thymine is replaced with Uracil.
anti sense strand
The DNA strand that serves as the template for synthesis of mRNA. It is complementary to the sense strand.
promoter region
A regulatory region a short distance upstream from the 5' end of a transcription start site that acts as the binding site for RNA polymerase. A region of DNA to which RNA polymerase binds in order to initiate transcription.
RNA polymerase
enzyme similar to DNA polymerase that binds to DNA and separates the DNA strands during transcription
nucleoside triphosphate
Molecule consisting of a nitrogenous base, a pentose sugar, and three phosphate groups, e.g., adenosine triphosphate (ATP) only difference is in the sugar(deoxirbose) compared with ribose. Is what is actually added to a growing neuclotide strand by DNA Po
terminator
someone who exterminates (especially someone whose occupation is the extermination of troublesome rodents and insects)
mature mRNA
In eukaryotes, transcription produces a long RNA, pre-mRNA, which undergoes certain processing events before it exits the nucleus; mature mRNA is the final functional product.
translation
(genetics) the process whereby genetic information coded in messenger RNA directs the formation of a specific protein at a ribosome in the cytoplasm; consisting of initiation, elongation, translocation and termination, all in 5'-3' direction
t RNA
transfer RNA; type of RNA that carries amino acids to the ribosome, carries amino acids to the ribosome to make proteins; anticodon using ATP for energy
ribosome structure
Two subunits made of ribosomal RNA and proteins; can be free in cytosol or bound to ER; three t RNA binding sites and mRNA binding sites
peptide bond
the chemical bond that forms between the carboxyl group of one amino acid and the amino group of another amino acid
polysomes
group of ribosomes moving along the same mRNA as they simultaneously translate it
start codon
specific codon (AUG) that signals to the ribosome that the translation commences at that point
stop codon
A group of nucleotides that does not specify a particular amino acid, but instead serves to notify the ribosome that the protein being translated is complete. The stop codons are UAA, UGA, and UAG. They are also known as nonsense codons.
free ribosomes
ribosomes that float in the cytosol to make the proteins that are used within the cell.
bound ribosomes
ribosomes that are attached to the endoplasmic reticulum to make proteins to be exported, to be embedded in membranes, and to be shipped elsewhere within the cell
fibrous protein
principle structural proteins that are long, insoluble in water, secondary structure is the most important; examples: collagen, keratin & myosin.
globular protein
a protein that folds into a compact shape so that the polar and ionic amino acids are on the outside and the nonpolar amino acids are on the inside. They function as enzymes, hormones, membrane pumps and channels, membrane receptors andinter/intracellular
quartenary structure of protein
more than one polypeptide chain bonded together, only then does polypeptide become function protein, hydrophobic interaction
tertiary structure of protein
how the chain folds into globules in three dimensions. This folding is due to interactions between the R groups of distant amino acids
prosthetic group
the non-protein component of a conjugated protein
conjugated protein
A compound, such as hemoglobin, made up of a protein molecule and a nonprotein prosthetic group.
polar amino acids
amino acids whose side chains contain electronegative atoms, resulting in an uneven distribution of electrons over the side chain portion of the molecule
non polar amino acids
have nonpolar hydrocarbons for their r groups which are neutrally charged, Leucine
Proline
Alanine
Valine
Glycine
Methionine
Tryptophan
Phenylalanine
Isoleucine
functions of protein
Transport (hemoglobin); structure (collegen); immune (antibodies); regulatory (hormones that control functions); contractile (muscle movement); catalytic (enzymes
enzyme induced fit model
Binding of a substrate within the active site causes conformational changes within the enzyme such that the number of interactions is increased
activation energy
The amount of energy that reactants must absorb before a chemical reaction will start.
exothermic reaction
a chemical reaction in which heat is released to the surroundings
competitive inhibition
The process in which a different substrate goes into the active site of an enzyme, thus shutting down the enzyme and not allowing it to function
non-competitive inhibition
substances that attach to binding site on an enzyme other than the active site, causing a change in the enzyme's shape and loss of affinity for its subtrate
allosteric sites
Enzymes binds here. Can also bind regulatory molecules in enyzme region. Binding changes the shape of enzyme in a way that enhances or inhibits its function.
end product inhibition
is a negative feedback process which regulates the reaction rate. If it gets too much it begins to produce less if it becomes scarce or doesn't produce enough it begins to produce more
metabolic pathways
Series of progressive chemical reaction steps involving energy production or conversion.