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45 Cards in this Set

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Point Mutations
A change in a gene at a single nucleotide pair.
Poly-A Tail
The modified end of the 3' end of the mRNA consists of the addition of 50-250 adenine nucleotides.
Polyribosomes
An aggregation of several ribosomes attached to one mRNA molecule found in both prokaryotic/eukaryotic cells that allows cell to make many copies of a polypeptide quickly.
Primary transcript
Initial RNA transcript also known as pre-mRNA transcribed from a protein-coding gene.
Promoter
Specific nucleotide sequence in DNA that binds RNA polymerase and indicates where to start transcribing RNA
Ribosomes
cell organelle constructed in the nucleolus that functions in protein synthesis. composed of 2 subunits: rRNA and
RNA processing
Modification of RNA before it leaves the nucleus, transcription of a protein-coding eukaryotic gene that results in pre-mRNA
spliceosome
complex assembly that interacts with the ends of an RNA intron in splicing RNA to release introns while joining adjacent exons
signal peptide
stretch of amino acids that targets a protein to a specific destination in a eukaryotic cell
signal recognition particle(SRP)
protein-RNA complex that recognizes a signal peptide as it emerges from the ribosome.
Template strand
One of 2 DNA strands that serves as a template for ordering the sequence of nucleotides in an RNA transcript
Transfer RNA
RNA molecule that functions as an interpreter between the protein and nucleic acid by taking an amino acid and recognizing the appropriate condons in the mRNA
Reading frame
the way mRNA nucleotides are arranged in codons by the mRNA-translating machinery
Ribosomal RNA
The most abundant type of RNA, component of ribosomes, coordinates sequential coupling of tRNA molecules to mRNA codons
Ribozymes
enzyme-like RNA molecules that catalyze reactions during RNA splicing
RNA polymerase
enzyme that pries 2 strands of DNA apart and hooks RNA nucleotides to the DNA template by base-pairing. It can only assemble in the 5' - 3' direction and is able to start chain without primer.
RNA splicing
removal of noncoding introns of the RNA molecule after initial synthesis
TATA
promoter DNA sequence crucial to the transcription initation complex, about 25 nucleotides upstream from transcriptional start point
Terminator
special sequence of nucleotides in DNA that mark the end of a gene, signaling RNA polymerase to release newly made RNA molecule and departs from the gene
Transcription
synthesis of RNA on a DNA template
transcription factors
regulatory protein molecule that binds to DNA and stimulates transcription of specific genes
Transcription initiation complex
completed assembly of transcription factors and RNA polymerase bound to the promoter
Transcription unit
stretch of DNA that is transcribed to an RNA molecule
Translation
synthesis of a polypeptide using genetic information encoded in an mRNA molecule. Cell must translate the base sequence of polypeptide.
Triplet Code
3 nucleotides that specify amino acids for polypeptide chain
Wobble
violation of the base-pairing rules on the 3rd nucleotide on the 5' end of a tRNA molecule that can form H bonds with more than one kind of base on the 3rd nucleotide on the 3' end of a codon
5' cap
5' end of a pre-mRNA molecule modified by addition of a cap of guanine nucleotide
A site
One of a ribosome's 3 binding sites for tRNA during translation, holds the tRNA carrying the next amino acid to be added to the polypeptide chain
Alternative RNA splicing
type of regulation at the RNA-processing level in which different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns
Aminoacyl-tRNA synthetase
enzyme that joins each amino acid to correct tRNA. active site only fits a specific combination of amino acid and tRNA
anticodon
specialized base triplet at one end of a tRNA molecule that recognizes a particular complementary codon on an mRNA molecule
base-pair substitution
type of point mutation; the replacement of one nucleotide and its partner in the complementary DNA strand by another pair of nucleotides
Codon
mRNA base triplets written in 5' to 3' direction, each specifying which of 20 amino acids will be incorporated at position along the polypeptide
domains
independently folding part of a protein
frameshift mutation
mutation occuring when the number of nucleotides deleted/inserted is not a multiple of 3, resulting in improper grouping of the following nucleotides into codons
E site
one of ribosome's 3 binding sites for tRNA during translation. discharged tRNAs leave the ribosome through this site
Exons
coding region of eukaryotic gene, can only be expressed when introns are removed
introns
noncoding, intervening sequence of nucleotides between coding regions
mRNA
type of RNA synthesized from DNA that attaches to ribosomes in the cytoplasm and specifies the primary structure of protein
missense
common type of mutation, base-pair substitution in which new codon makes sense in that it still codes for an amino acid
mutagens
chemical/physical agent that interacts with DNA to cause a mutation, some interfere with DNA replication by inserting themselves
Mutations
change in DNA of a gene that ultimately creates genetic diversity
nonsense mutation
mutation that changes an amino acid codon to one of the 3 stop codons resulting in shorter nonfunctional protein
one gene-one polypeptide hypothesis
premise that a gene is a segment of DNA that codes for one polypeptide
P site
one of a ribosome's 3 binding sites for tRNA, holds the tRNA carrying the growing polypeptide chain