Unit 3 - AOS 1 - CH 1.4 - Genetic code, transcription, translation

Question 1

5 points of the genetic code

Answer 1

TRIPLET CODE:
- each triplet = codon
- isread independantly, without overlapping from adjacent codons

UNIVERSAL CODE:
- Nearly all organisms use the same codons to code for specific amino acids.

UNAMBIGUOUS:
- eahc codon codes for 1 amino acid

DEGENERATE:
- each amino acid may be coded for by multiple different codons

NUCELOTIDES:
- monomer of nucelic acid and combine to make nucelic acid.

Question 2

Definition of transcription

Answer 2

“Processing of opying the genetic instructions present in DNA to mRNA, which is now in a form which can leave the nucleus”

Question 3

Coding Strands

Answer 3

5’ - 3’

• One strand of DNA that is complementary to the template strand

Question 4

Template Strands

Answer 4

3’ - 5’

• One strand f DNA that is used to produce complementary mRNA strand during transcription

Question 5

what are the 5 steps of transcription

Answer 5

STEP ONE:
An enzyme ‘RNA polymerase’, attaches to specific promoter sequences of DNA in the upstream region of the template strand. It seperates the DNA helix (template adn coding strand)

STEP TWO:
The base sequene of DNA template guides the building of a complementary mRNA copy (sequence)
- The RNA polymerase moves on DNA template in 3’-5’ direction
- As it moves complementary nucelotides (free floating) join and add to the growing 3’ end of the mRNA chain.

STEP THREE:
Pre-mRNA begins to break away from the template strand

STEP FOUR:
DNA begins to recombine

STEP FIVE:
RNA processing occures where:
- Introns (non-coding regions and lowercase) are cut out & discarded.
- Extrons (coding region & upper case) bond together as one
- all done through splicesosome -> removes introns and makes mature mRNA from imaature pre-mRNA

Question 6

Spliceosome

Answer 6

Used during RNA processing
- A complex molecule that removes the introns to make pre-mRNA (unprocessed RNA) -> mRNA (mature

Question 7

capping (RNA processing)

Answer 7

Protects from enzyme attack, stability, helps attach to the ribosome

Question 8

Tail (RNA processing)

Answer 8

Stability, facilitates, mRNA export from the nucelus

Question 9

Definition of translation

Answer 9

The process of a ribosome creating a protein”

Question 10

Method of translation

Answer 10

STEP ONE:
mRNA arrives at a ribosome

STEP TWO:
Ribosome reads one codon at a time start with ‘AUG’

STEP THREE:
tRNA delivers the proper amino acid, with a anticodon to help prevent delivery of wrong amino acid.

STEP FOUR:
Translation ends when ‘stop’ codon is reached (UAA< UAG< UGA)