Gene Expression Flashcards
What process copies DNA to mRNA?
Transcription
Where does transcription occur?
In the nucleus
What process converts mRNA to proteins?
Translation
Where does translation occur?
In the cytoplasm.
What are the three stages of transcription and translation?
Initiation, elongation, termination.
During DNA replication, name the enzyme, substrate and template used.
Enzyme - DNA polymerase
Substrate - dNTPs
Template - DNA
During transcription, name the enzyme, substrate, and template used.
Enzyme - RNA polymerase
Substrate - NTPs
Template - DNA
During translation, name the enzyme, substrate and template used.
Enzyme - ribosome
Substrate - amino acids
Template - mRNA
What is the name of the promoter sequence used to indicate transcription?
A TATA box (TATAAA)
Does the TATA box exist on the coding strand or the template strand?
Coding strand
The code ATATTT exists on the template strand and the complimentary code TATAAA on the coding strand initiates transcription.
Does the template strand run 5’ to 3’ or 3’ to 5’? What does that make the coding strand?
Template strand - 5’ to 3’
Coding strand - 3’ to 5’
What does rRNA stand for?
Ribosomal RNA
What does mRNA stand for?
Messenger RNA
What does tRNA stand for?
Transfer RNA
What are the names of the capping systems used at the 5’ end and the 3’ end of the complete mRNA strand after transcription?
5’ - a 5’ cap
3’ - a polyA tail followed by the sequence AAAAA… until ten 3’ termination end.
What does capping do?
Give protection and stop degradation.
What happens to pre-mRNA to make the complete mRNA strand?
The introns are spliced from the pre-mRNA to create a shorter mRNA strand of exons.
What codons ALWAYS starts translation and what bases is it made up of?
Methionine
A - Alanine
U - Uracil
G - Guanine
How are the complimentary bases on a tRNA stem loop bonded?
Through hydrogen bonds
What is an anticodon?
An anticodon on a tRNA molecule which is complementary to the codon on the mRNA strand. An anticodon lies at the bottom of the stem loop of tRNA and codes for a specific amino acid.
What is tRNA’s function?
TRNA is a molecule that transfers amino acids from the nucleus to the ribosome for protein synthesis.
What is the shine-dalgarno sequence?
The coding sequence where the ribosome joins the strand, located about 8 bases up from start codon. Translation does not begin at this point. There a short sequence of non-coding region before the start codon begins coding.
What do E, P and A regions stand for and where are they located?
E = E side, this is the left hand side of the start codon at the beginning of translation. P = Peptidyl site, on the start codon, in the middle. A = Aminoacyl site, to the right of the start codon, the next codon to be coded.
In translation, what happens in elongation?
A peptide bond is created between the amino acid coded on the P site and and the amino acid on the A site. The ribosome then moves from left to right (5’ to 3’), so the original P position is taken up by E, A by P and A is a new codon. As the ribosomes moves along the strand a polypeptide chain is created with the amino acids coded in translation, creating a protein.
