Gene Expression Flashcards
What is the process of making mRNA from DNA called?
Transcription
What is the process of making proteins from mRNA?
Translation
Where does transcription occur?
Nucleus
Where does translation occur?
Cytoplasm
What is a gene?
Stretch of DNA with a chromosomal locus
Is mRNA single stranded or double stranded?
Single stranded
What are the three stages of transcription and translation called?
Initiation, elongation and termination
What is the enzyme involved in transcription?
RNA polymerase
What are the activated substrates involved in transcription?
NTPs
What are the activated substrates involved in translation?
Amino acids
How is transcription initiated?
Recognition and binding of promoter region
In which direction does transcription occur?
5’ to 3’
What is a TATA box?
A type of promoter sequence that can initiate transcription
What can the DNA template strand also be known as?
Non-coding strand
What sequence does the DNA template strand have?
Has a complimentary sequence to mRNA
What sequence does the DNA coding strand have?
Same sequence as mRNA, complementary sequence to template strand
What are the 3 steps involved in RNA processing?
Capping, tailing and splicing
What is capping of RNA?
Methylated guanine cap is added to the 5’ end to protect against degradation
What is tailing/polyadenylation of RNA?
PolyA tail is added at the 3’ end to protect against degradation
What is splicing?
Removal of introns from pre-mRNA
What happens to mRNA after it is processed?
Moves out of nuclear pores and into the cytoplasm to be used as a template for translation
Why does capping protect against degradation?
A 5’-5’ linkage is created which is unusual
What are ribosomes made up of?
Ribosomal RNA and different proteins
In eukaryotes, what are the subunits of the 80S ribosome?
40S and 60S subunits
In eukaryotes, how many rRNAs and proteins are there in ribosomes?
3 rRNAs and 56 proteins
What are the 5 types of RNA?
rRNA, mRNA, tRNA, miRNA and noncoding RNA
What makes up most of the RNA in a cell?
rRNA
Which type of RNA does RNA polymerase I make?
rRNA
Which type of RNA does RNA polymerase II make?
mRNA
Which type of RNA does RNA polymerase III make?
tRNA
Which type of RNA are there few kinds but many copies?
rRNA
Which type of RNA are there many kinds but few copies?
mRNA
What is meant by the degenerate nature of the genetic code?
Some amino acids have multiple codons
What are some features of the genetic code?
Triplet code, degenerate, non-overlapping
In which direction is polypeptide chain extension?
N terminus to C terminus
What is the initiation codon?
AUG (methionine)
What are the termination codons?
UAA, UAG, UGA
What is the shape of tRNA?
Clover
How are stem loops formed in tRNA?
Hydrogen bonds are formed between anti-parallel, complementary sequences
What is inosine?
Nucleoside formed when hypoxanthine is attached to ribose
What are wobble base pairs?
A wobble base pair is a pairing between two nucleotides in RNA molecules that does not follow Watson-Crick base pair rules.
What are the four main wobble base pairs?
G-U, I-U, I-A, I-C
Which codon specifies the first amino acid in any protein?
AUG
Why are there only a few kinds of rRNA but many different kinds of mRNA?
This is because not many kinds of rRNA are needed to form ribosomes but as there are many kinds of proteins that mRNA make, there must be lots of different kinds
Why does DNA polymerase have the ability to proofread but this capacity is limited in RNA polymerases?
DNA polymerase errors will be propagated to other cells and changes will be inherited
Cordycepin inhibits the synthesis of mRNA. How does this work?
It can be incorporated into RNA and inhibit transcription and the synthesis of mRNA due to the absence of the hydroxyl group at the 3’ position so no sugar-phosphate bonds can be formed
What is cordycepin?
Also known as 3’-deoxyadenosine. It is a deriverative of the nucleoside adenosine but lacks the OH group in the 3’ position of its ribose part.
