Principles Overall

Question 1

What does DNA Replication need to start?

Answer 1

RNA Primer, DNA polymerase, ATP & free nucleotides

Question 2

What’s the process of DNA Replication?

Answer 2

o Helicase unwinds DNA (and stops it rewinding)

o DNA polymerase synthesises complementary strands (leading – 3’ to 5’ and lagging – 5’ to 3’)

o Primase synthesises an RNA primer

o Lagging strand is replicated in Okazaki fragments

o RNA primers are degraded

o If wrong nucleotides are detected, DNA polymerase has a 3’ to 5’ exonuclease activity that removes them.

Question 3

What is the process of transcription?

Answer 3

o RNA polymerase binding

o DNA chain separation

o Transcription initiation

o Elongation
 addition of further nucleotides to RNA chain
 RNA chain is synthesised in 5’ to 3’, complementary to template strand

o Termination (release of finished RNA) 
 RNA cleaved, releasing It and disassociating polymerase

Question 4

What’s the process of translation?

Answer 4

o Initiation
Ribosomal subunit binds to 5’ end of mRNA and moves along til start codon
 tRNA base-pairs w/ start codon
 Large subunit joins assembly and initiator tRNA is located in P site

o Elongation
 next aminoacyl-tRNA goes to A site
 Next aminoacyl-tRNA picked up
 Peptide bond formation catalyesed by peptidyl transferase and translocation
ribosome moves along mRNA
 “Empty” tRNA moves to E site
 tRNA w/ the growing peptide moves from A to P site
 site is free for next aminoacyl-tRNA & elongation cont.

o Termination
	Occurs when A site of ribosome reaches stop codon
 Release factor binds to stop codon
 Finished protein is cleaved off tRNA
 RNA’s dissociate
 Whole process restarts

Question 5

What does RNA Polymerase 2 do?

Answer 5

synthesises mRNA

Question 6

What are the 8 Stages of embryo development?

Answer 6

Gametogenesis
Fertilisation
Cleavage
Implantation
Gastrulation
Embryonic Folding
Organogenesis

Question 7

Where does implantation occur?

Answer 7

At the uterine wall

Question 8

What does trisomy 14 result in?

Answer 8

Miscarriage

Question 9

What does Trisomy 18 result in?

Answer 9

Edward Syndrome

Question 10

What does a dysfunctional chromosome 15 result in?

Answer 10

Angelman syndrome

Question 11

What happens if there’s only 1 X?

Answer 11

Turner syndrome

Question 12

What happens if you have XXY?

Answer 12

Klinefelter

Question 13

What’s a Robertsonian translocation?

Answer 13

Where two acrosomal chromosomes are stuck from end to end

Question 14

What’s the 1st line genetic test for paediatric referrals?

Answer 14

aCGH (checks for duplication/deletion)