Chapter 17 Flashcards
gene expression
process by which DNA directs the synthesis of proteins
transcription
synthesis of rna using information in the dna
messenger rna (mrna)
rna molecules that carry genetic messages from the dna to the protein synthesizing machinery of the cell
translation
synthesis of a polypeptide using the information in the mRNA
ribosomes
molecular complexes that facilitate the orderly linking of amino acids into polypeptide chains
triplet code
the genetic instructions for a polypeptide chain are written in the DNa as a series of nonoverlapping three nucleotide words
coding strand
nontemplate dna strand
rna polymerase
pries the two strands of DNA apart and joins together rna nucleotides complementary to the dna template strand
promoter
the dna sequence where rna polymerase attaches and initiates transcription
terminator
the sequence that signals the end of transcription
transcription unit
the stretch of dna downstream from the promoter that is transcribed into an rna molecule
start point
the nucleotide where rna polymerase actually begins synthesizing the mrna and typically extends several dozen or so nucleotide pairs upstream from the start point
transcription factors
collection of proteins
transcription initiation complex
the whole complex of transcription factors and RNA polymerase II bound to the promoter
TATA box
crucial promoter DNA sequence
RNA processing
both ends of the primary transcript are altered
5’ cap
a modified form of G nucleotide
RNA splicing
large portions of the RNA primary transcript molecules are removed and the remaining portions are reconnected
introns
noncoding segments of nucleic acid that lie between coding regions
exons
regions other than introns; called exons because they are eventually expressed
spliceosome
large complex made of proteins and small rnas that binds to several short nucleotide sequences along an intron including key sequences at each end
ribozymes
rna molecules that can function as enzymes
domains
discrete structural and functional regions
transfer RNA
translator
wobble
flexible base pairing at this codon position
nucleotide pair substitution
the replacement of one nucleotide and its partner with another pair of nucleotides
silent mutation
no observable effect on phenotype
missense mutations
little effect on protein
insertions
additions of nucleotide pairs in a gene
deletions
losses of nucleotide pairs in a gene
frameshift mutation
occurs whenever the number of nucleotides inserted or deleted is not a multiple of three
mutagens
interact with DNA in ways that cause mutations
gene editing
altering genes in a specific predictable way
