Gene Expression Flashcards
What enzyme do you need to make DNA?
DNA polymerase
What activated substrates do you need to make DNA?
Deoxynucleotides triphosphates
What template is used to make DNA?
DNA
What enzyme is needed to make RNA?
RNA polymerase
What activated substrate is needed to make RNA?
Ribonucleotides triphosphates
What template is used for making RNA?
DNA
What enzyme is needed to make a polypeptide?
Ribosomes
What activated substrate is needed to make a polypeptide?
Amino acids
What template is needed to make a polypeptide?
mRNA
What happens in the initiation stage of transcription?
TATA box sets the direction of transcription
Transcription begins at the promoter region as acts as a recognition site for RNA polymerase
DNA helix unwinds and opens
What happens in the elongation stage of transcription?
RNA polymerase slides along the template strand
Complementary bases pair up
RNA polymerase link nucleotides from the 3’ end
What happens in the termination stage of transcription?
Once the RNA polymerase reaches the end section the mRNA is complete and so dissociates
What is capping in RNA processing?
At 5’ end a linage is created which provides protection against degradation
What is polyadenylation in RNA processing?
A polyA tail is added at the 3’ end
Protects against degradation
E.g. AAAAAAA
What is splicing in RNA processing?
Removal of introns
What is the name for many ribosomes?
Polyribosome or polysome
How do prokaryotes and eukaryotes ribosomes differ?
Eukaryotes ribosomes are bigger
What are the different types of RNA?
Ribosomal- few kinds, most of RNA 80%
Messenger- 100,000 of kinds, least of RNA 2%
Transfer- 100 kinds, some RNA 15%
What are the properties of the genetic code?
4 letter DNA language to 20 letter protein language Triplet code Degenerate Non overlapping Comma less 5' to 3' becomes N to C
What is a wobble base?
A single tRNA species can recognise more than one codon
G and U can bind at the wobble base
What happens at the initiation stage of translation?
mRNA binds to small ribosomal subunit upstream form start codon
Complementary base pairing occurs between codon and anticodon
Large ribosomal subunit will bind
What happens at the elongation stage of translation?
tRNA binds to the A site of the ribosome and forms a peptide bond with the amino acid in the P site
The tRNA in the E site will then leave
What happens in the termination stage of translation?
Stop codon is reached
Release factor binds to the A site at a stop codon and the polypeptide is released
