8. Transcription & Translation Flashcards
Where does transcription take place?
Nucleus
Which enzyme is involved in transcription?
RNA polymerase
What substrates are required for transcription?
NTP’s
What are the 3 steps of transcription?
Initiation, Elongation & Termination
What direction does RNA polymerase elongate?
5’ to 3’, will extend from the 3’ end
How is transcription initiated?
Promotor region with a TATA Box is recognised by transcription factors and recruits RNA polymerase
What point does transcription begin from?
+1
What is the template strand in transcription?
The strand that the RNA polymerase is reading from, the mRNA will be complementary to this strand.
What is the coding strand in transcription?
The strand which is complementary to the template strand and will be identical to the mRNA.
What will be the only difference between the coding strand and the mRNA?
mRNA will have uracil instead of thymine
How is transcription terminated?
Terminator region at the end of the gene causes RNA polymerase to detach.
What 3 things are carried out during RNA processing?
- Capping at the 5’ end
- Poly A tail at the 3’ end
- Splicing to remove introns
What is the function of the 5’cap and 3’ poly A tail?
To protect the mRNA against degradation so that it can be translated.
What type of link attaches the Methionine at the 5’ Cap?
5’-5’ linkage
Which enzyme is responsible for the addition of the Poly A tail/
Poly A polymerase
What occurs prior to the addition of a Poly A tail at the 3’ end?
Cleavage of the mRNA end by specific endoncucleases
What 2 subunits are in the eukaryote ribosome?
40S and 60S subunit and an 80S ribosome
What type of RNA polymerase synthesises mRNA?
RNA polymerase II
What enzyme is involved in translation?
Ribosome
What is the ribosome made up of?
Proteins and rRNA
What type of bonds are present in the stem loops of tRNA?
hydrogen bonds between the anti-parallel, complementary sequences
What direction are proteins synthesised in?
N to C terminal
What direction do ribosomes read in?
5’ to 3’
What are the 3 sites within RNA?
E, P and A
How many codons can a ribosome read at one time?
2
Does translation require energy?
Yes, binding of each aminoacyl- tRNA uses GTP energy and ribosome translocation uses GTP energy.
What site does the first Met amino acid start in?
P site
Which site contains the growing peptide chain?
P site
What is the E site?
Exit site where tRNA leaves
What enzyme catalysts peptide bond synthesis in translation?
Peptidyl transferase
