d1.2 protein synthesis Flashcards
sense strand
actually contains the genetic material for the polypeptide
antisense strand
complimentary strand
- not codable in the 5’ to 3’ direction
mRNA vs sense strand
mRNA is a copy of the sense strand (T is replaced by U)
gene
segment of dna that contains coded information for synthesising a polypeptide molecule
what does ribosome convert (what to what)
dna to amino acid
what is the only thing that is copied
gene segment
start codon
AUG
what can cells do through gene expression
cells can specialise into different types
what does cell specialisation affect
whether or not a gene will be transcribed for ribosomes to create the necessary polypeptide
transcription
first stage of gene expression, key stage at which expression of a gene can be switched on and off
how does the dna fit in the nucleus
wrapped around histone to form nucleosome
how does nucleosome affect gene expression
by prompting or limiting dna transcription
what does a condensed chromatin mean
no genes are expressed since dna transcription is inhibited
what does an open chromatin mean
genes are expressed since it promotes dna transcription
what does the rna polymerase attach to + what does it do
- unzip the double helix
- attach onto the antisense strand (template strand)
why does the dna polymerase attach to the antisense strand
as it moves, it copies and makes rna that is complementary to the antisense strand
after transcription what does the ribosomes do (+ what do they use)
uses tRNA to synthesise the polypeptide using the mRNA
what do tRNA contain
anticodon that is complementary to the codon in the mRNA
what do ribosomes do after transcription at the 3’ end
carries the amino acid that the codon codes for
2 types of ribosomes
- free ribosomes
- bound ribosomes
where will all mRNA go to first
free ribosomes
how to tell if a gene is expressed
if it is condensed, its not expressed
how is the mRNA identical to the sense strand except T to U
mRNA uses RNA polymerase which attaches to the antisense strand
what would happen is the ribosome is bound on the rough er
polypeptide would go outside of the cell through exocytosis
dna structure of tRNA
clover leaf
brief process of translation
- initiation
- elongation
- termination