Gene to Protein

Question 1

What are the 3 main steps of Gene expression

Answer 1

Transcription of RNA from DNA
Processing of pre mRNA transcript
Translation of the mRNA transcript to a protein

Question 2

Overview of Transcription

Answer 2

1. Initiation- Polymerase attaches to Promotor DNA section
2. Elongation- Downstream transcribe of Dna= mRNA
3. Terminantion at the terminator

Question 3

Describe DNA and Rnas structural difference

Answer 3

DNA- double stranded

RNA single stranded & Uracil replaces Thymine

Question 4

Describe Initiation transcription

Answer 4

1. Eucaryotic Promotor on the DNA
2. Several transcription factors attach to the DNA
3. Transcrip initian complex forms (transcription factors + RNA polymerase

Question 5

Describe Elongation and termination transcription

Answer 5

ELongation: RNA is formed from 3- 5 on the template strand
- Phosphodiester bond formed
Terminantion:
Polyadenylation nuclear enzymes is transcribed and releases Pre MRNA and RNA polyermase

Question 6

WHat is the enzyme that codes for the release of mRNA from DNA

Answer 6

polyadenylation nuclear enzyme

Question 7

End of Transcription means what for the pre mRNA

Answer 7

Pre RNA is now ready for further processing

Question 8

Describe the pre- mRNA processing with capping and tailing

Answer 8

Capping- added to the 5 end. guanine nucleotide
Tailing= 3 end: adenine nucleotide
Caping and tailing = stability and allow ribosomal attachment within the Cytoplasm

Question 9

Describe Pre mRNA features

Answer 9

Exons- coding regions

Introns- non coding region (intervening exon)

Question 10

Describe features in Processing of pre m RNA

Answer 10

capping tailing

& splicing

Question 11

Describe Splicing

Answer 11

Splicing occurs when Splicisome (and small RNA) remove introns and join remaining exons to form Mature mRNA

Question 12

Describe Alternative Splicing

Answer 12

When multiple forms of mature Rna are formed by 1 pre m RNA this is because multiple combinations of exons are joined together.

Question 13

Describe how to transcribe DNA

Answer 13

mRNA are in groups of 3
all letters apart from Uracil go to the same letter.
Withing DNA Thymine is replaced by Uracil

Question 14

3 main steps of Translation

Answer 14

Initiation, elongation, termination

Question 15

Describe Translation

Answer 15

Occurs in Ribosomes within the cytosol
tRna with specific anticodons and amino acids
cause a hydrogen bond to mature MRNA
Amino acid- peptibe bond causes a polypeptide chain

Question 16

What enables the formation of polypeptide bonds to form

Answer 16

mRNA and tRNA held together with ribosomes enable formation of polypeptide

Question 17

What are tRNa

Answer 17

Translator that is the physical link between mRNA and amino acid sequence

Question 18

Translation initiation phase

Answer 18

tRNA/ mRNA and small ribosomal unit are bound together
Ribosomal unit scans down mRNA to find start code (AUG)
When start codon has been found Hydrogen between mRNA and tRNA forms
Large subunit attaches (ribosome) and initiation is completed

Question 19

Translation Elongation phase

Answer 19

1. Codon recogonisition- A site
2. Peptide bond formation- P site
3. Translocation - Is the ability to move tRNA to each site. Requires energy

Question 20

How is empty codons reloaded into the cytoplasm

Answer 20

using aminoacyl-tRNA synthases

Question 21

Describe Termination in Translation

Answer 21

1. ribosome reach’s stop codon on mRNA- release factor found
2. factor promotes hydrolysis, polypeptide becomes free
3. ribosomal units mRNA and other components dissociate - energy required