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54 Cards in this Set

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  • Back
promoter
site where RNA polymerase initially binds to DNA
initiation
first stage of transcription; requires a promoter
transcription factors
bind to the promoter during transcription; these proteins facilitate binding of RNA polymerase to the site
transcription initiation complex
completed assembly of transcription factors and RNA polymerase at the promoter region
elongation
RNA polymerase continues building the RNA strand ; the newly synthesized RNA strand easily separates from the DNA and the DNA molecule “zips up” behind RNA polymerase, reforming the double helix
termination
the end of RNA transcription
codons
sequences of three bases that instruct for the addition of a particular amino acid (or a stop) to a polypeptide chain;
triplet code
a 3-base code
stop codons
do not code for an amino acid but instead will end the protein chain
coding region
codes for protein synthesis
leader sequence
the mRNA strand prior to the start codon is called the 5’ untranslated region or this
trailing sequence
the mRNA strand after the stop codon is called the 3’ untranslated region or this
Translation
using information in mRNA to direct protein synthesis
ribozyme
catalyzes peptide bond formation
anticodon
each tRNA has this region that will form a proper complementary basepairing with a codon on an mRNA molecule
aminoacyl-tRNA synthetases
tRNA is linked to the appropriate amino acid by enzymes called these; the result is aminoacyl-tRNA.
E site
where uncharged tRNA molecules are moved and then released
P site
where the completed part of the polypeptide chain will be attached to tRNA
A site
where the new amino acid will enter on an aminoacyl-tRNA as a polypeptide is made
initiation of translation
start of polypeptide production
initiator tRNA
recognizes the codon AUG, which is the initiation start codon
ribosome recognition sequence
where small ribosomal subunit binds to an mRNA in a prokaryote
initiation factors
proteins that help the small subunit bind to the initiator tRNA and mRNA
elongation in translation
the addition of amino acids to the growing polypeptide chain
elongation factors
assist in getting the charged tRNA to bind
translocation
takes place after elongation in translation; moving amino acids and nucleotides from the A site to the P site to the E site.
termination in translation
last step of translation where a stop codon signals the end for translation
termination factor
the termination factor causes everything to dissociate, freeing the polypeptide, mRNA, last tRNA, and ribosomal subunits all from each other
polyribosomes
as many as 20 ribosomes may be synthesizing protein from the same message - these are called what?
5’ cap
required for binding to eukaryotic ribosomes; makes eukaryotic mRNAs less susceptible to degradation and to promote the transport of the mRNA out of the nucleus
polyadenylation
the 3’ tail in RNA
polyadenylation signal
signals for the addition of a “tail” on the 3’ end of the mRNA
poly-A tail
the mRNA tail is a series of adenines called this
introns
stretches of bases that “interrupt” the sequence and must be removed
exons
regions that will not be removed from the sequence because they do not "interrupt" it
RNA splicing
the process of removing introns
snRNPs
made of small RNA molecules and proteins; associate with the mRNA in a complex called the spliceosome
spliceosome
catalyzes cutting out and removing an intron and joining together the exons
alternative RNA splicing
allows one DNA sequence to direct synthesis of two or more different polypeptides
domain
a region within the protein that has a specific function
exon shuffling
proteins consist of such functional domains which can be readily shuffled around during evolution to produce new proteins with novel catalytic functions
Mutations
changes in the DNA sequence
mutagens
DNA-damage inducers
carcinogens
mutagens that increase the likelihood of cancer
mutational hot spots
DNA regions that are more prone to mutations
point mutations
base substitution mutations; mutations that result in the substitution of one base for another
silent mutation
if the point mutation does not actually cause a change in what amino acid is coded for, it is called this
missense mutation
if the point mutation causes a change in what amino acid is coded for, it is called this
nonsense mutation
if the point mutation results in the formation of a stop codon where an amino previously was coded for, it is called this
transposon
some mutations are caused by pieces of DNA that can jump around the genome; such jumping DNA is called this.
constitutive genes (housekeeping genes)
genes that are constantly transcribed, with little or no regulation
repressors
transcription factors that suppress or stop gene expression
activators
transcription factors that either activate ( “turn on”) gene expression, or to enhance gene expression
enhancers
DNA regions, often far from the promoter, where activators will bind either directly or indirectly