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Flashcards in Gene Expression Deck (25)
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1

Where does transcription occur?

In the nucleus

2

What are the 3 stages of transcription?

Initiation, elongation and termination

3

What is the TATA region?

A section of DNA in the promoter region that is recognised by transcription factors which then bind to it

4

What type of RNA Polymerase is used in transcription?

Type 2

5

What type of bonds are formed to create the sugar phosphate backbone?

Phosphodiester bonds

6

What is mRNA capping?

Adding a guanine nucleotide to the mRNA via a 5' to 5' triphosphate linkage

7

What is polyadenylation?

The addition of lots of A bases onto the end of the mRNA.

8

How does polyadenylation occur?

A signal (termination) sequence is recognised by an endonuclease enzyme which cleaves the sequence and then the A bases can be added

9

What is splicing?

When peptide bonds are broke to remove the introns from the mRNA

10

What are introns and exons?

Introns are non coding DNA sequences whereas exons are coding DNA sequences.

11

How is translation initiated?

Special methionyl tRNA molecules recognise the 5' cap and bind to it, allowing the 40s ribosome subunit and other proteins to bind. The complex then moves along until a start sequence is recognised and the 60s subunit binds

12

What enzyme forms the peptide bonds in translation?

Peptidyl transferase

13

How is translocation terminated?

When a stop codon is reached a releasing factor protein bind to the A site of the 60s ribosome and water is used to break the peptide strand from the tRNA

14

What enzyme synthesises ribosomes?

RNA Polymerase 1

15

What subunits are prokaryotic ribosomes made up of?

A 50s and a 30s to give a 70s ribosome

16

What subunits are eukaryotic ribosomes made up of?

60s and 40s to give an 80s subunit

17

What enzyme produces tRNA?

RNA Polymerase 3

18

What enzyme attaches the amino acids to the tRNA molecules?

Aminoacyl tRNA synthetase

19

What is the advantage of wobble bases?

There is an increased efficiency of translation as their is more flexibility of which nucleotides can bind

20

Which base in the codon doesn't have to be paired correctly in wobble bases?

The third

21

Which additional nucleoside is found in tRNA molecules?

Inosine

22

What complex carries out splicing?

A spliceosome

23

What does tetracycline do?

Binds to the 30s subunit of bacterial ribosomes and prevents tRNA binding to the A site

24

What does erythromycin do?

Binds to the 50s subunit of ribosomes and prevents translocation

25

What does chloramphenicol do?

Binds to the 50s subunit of ribosomes and prevents peptidyl transferase