Session 8-Gene Expression Flashcards
What three things does the process of making a polynucleotide or polypeptide need?
Enzyme
Activated substrates
Template
What is the: Enzyme? Activated substrate? Template? For DNA?
DNA polymerase
dNTPs
DNA
What are the names of the three stages in making a polynucleotide or polypeptide?
Initiation
Elongation
Termination
What is the: Enzyme? Activated substrate? Template? For making RNA?
RNA polymerase
NTPs
DNA
What is the process of making RNA called?
Transcription
What is the: Enzyme? Activate substrate? Template? For making a polypeptide?
Ribosome
AA
mRNA
In transcription, what is involved in the initiation stage? (3)
Promoter recognition
Transcription initiation factors
RNA polymerase
Why is a TATA box important?
Transcription factor binding to a TATA box sets the direction of transcription
What happens in elongation in transcription?
5’ to 3’ chain growth
Which two methods protect mRNA against degradation?
Capping
Tailing or polyadenylation
What happens in capping?
A 5’ to 5’ linkage is created to provide protection against degradation
What happens in tailing or polyadenylation?
Occurs at the 3’ end of the chain (polyA tail)
Why are there methods to prevent mRNA degradation?
Because RNA is unstable and is always degrading so it needs to be controlled
What is splicing?
Occurs in the middle of the mRNA strand and involves the removal of introns and is sequence dependent
What are the 5 different types of RNA?
rRNA mRNA tRNA miRNA Noncoding RNA
Which RNA polymerase is used to make rRNA?
RNA polymerase I
Which RNA polymerase is used to make mRNA?
RNA polymerase II
Which RNA polymerase is used to make tRNA?
RNA polymerase III
True or false: every transcription starts with AUG codon so every protein starts with methionine
TRUE
What are the three termination codons?
UAA
UAG
UGA
What is inosine?
Base in tRNA anticodons which can read U, C and A in the 3rd position
What is a wobble base?
Wobble base pairs do not follow the normal base pair rules: G-U I-U I-A I-C
What happens in initiation of translation?
AUG codon recognition
Special methionyl tRNA
Ribosome
What happens in elongation in translation?
N to C chain growths
Aminoacyl tRNAs - A site is the point of entry for aminoacyl tRNA (except for first aminoacyl tRNA which enters at P site)
P site is where peptidyl tRNA is formed in ribosome
What is aminoacyl tRNA?
tRNA to which AA is chemically bonded and delivers AA to ribosome for incorporation into polypeptide chain that is being produced
What happens in termination of translation?
Stop codons are identified
What are the subunits found in eukaryotic ribosomes?
40S and 60S subunits, which make up 80S
What are the subunits found in prokaryotic ribosomes?
50S and 30S which make up a 70S ribosome
What is a TATA box?
DNA sequence that indicates where a genetic sequence is read and decoded. It is a type of promoter sequence, which specifies to other molecules where transcription begins
