17

Question 1

Each _____ carries an ____ ____ to be added to the _________ ____

Answer 1

Each tRNA carries an amino acid to be added to the polypeptide chain

Question 2

Each _____ has a different ______ _____ but about the same overall ____

Answer 2

Each tRNA has a different base sequence but about the same overall shape

Question 3

What do codons do?

Answer 3

The oceans within the coding region of the mRNA specifies the amino acid sequence of the polypeptide chain

Question 4

TRNA in translation

Answer 4

Question 5

Translation initiation

Answer 5

Question 6

Translation elongation

Answer 6

• codon under A site will be recognised by a complementary tRNA and tRNA will diffuse in
• triggers peptide bond formation, amino acid chain is transferend into tRNA in the A site (uses ATP)
• ribosome moves along 3 base pairs (one codon) - using ATP, fist tRNA in E write floats away and a new tRNA is now able to bind

Question 7

Translation termination

Answer 7

• at the stop codon, release factor comes in and triggers disassembly of the complex, breaking of peptide bond from tRNA (hydrolysis )

Question 8

Mutation causing PKU

Answer 8

• single base pair change in the phenylalanine hydroxylase gene
  Arg —-> Trp

Question 9

Mutation causing PKU

Answer 9

• single base pair change in the phenylalanine hydroxylase gene
  Arg —-> Trp

Question 10

Steps of mutation causing PKU

Answer 10

Question 11

Types of mutations and their consequences on proteins

Answer 11

Substitition - change of one letter
- point mutation

Deletion - loss of one later
- frame shift mutation

Insertion - gain of one latter
- frame shift mutation

Question 12

Glucokinase

Answer 12

Enzyme in pancreatic B cells
- first step in breaking down glucose by adding a phosphate
- how a cell measures how much glucose is in blood and respond by making insulin

Question 13

How does MODY2 occur

Answer 13

• mutauiton in one glucoskinase gene (heterozygous)

Question 14

What does the mutation of glucokinase results in

Answer 14

= persisitant mild hyperglycaemia
- a type of diabetes called MODY2 ( maturity onset diabetes of the young, type 2)

Question 15

What happens when a cell is homozygous for non-functional glucokinase protien

Answer 15

Severe diabetes and very high blood glucose levels

Question 16

What do pancreatic B cells do in response to high glucose

Answer 16

Pancreatic b cells ‘sense’ ( using glucokinase) how much glucose is in the blood and release insulin when glucose is high (feed state)

Question 17

What does glucokinase do ? What does it sense?

Answer 17

Glucokinase is a key enzyme in glucose sensing as it determines how much glucose is broken down – therefore how much insulin is produced

Question 18

What mutation causes MODY2

Answer 18

Question 19

What happens if you’re homozygous for glucokinase

Answer 19

• sever diabereties and very high blood glucose levels
• decrease insulin
• increase blood glucose

Question 20

Mutation that clauses MODY2

Answer 20

Question 21

process of genetic testing - PCR

Answer 21

• obtain some cells
• isolate DNA
• PCR amplifying a specific gene sequence
• detect genetic difference of interest

Question 22

Components of PCR

Answer 22

• DNA from cells
• DNA nucleotides
• primers with sequences that can base pair with that region of DNA that you want to amplify
• Taq DNA polymerase

Question 23

What is a primer used in PCR

Answer 23

Primer - short sequences (~20 nucleotides) that is chemically synthesised

Question 24

Steps of PCR

Answer 24

1. Heat DNA to 95*c to seperate DNA strands
2. Cool to ~60*c to anneal (base pair) a DNA primer
3. Heat DNA to 72*c to allow Taq DNA polymerase to copy the DNA
   - copying cycle is complete - repeat cycle - three steps

Question 25

Genetic testing - detecting sequence differences

Answer 25

Question 26

What is Hindlll

Answer 26

A restriction enzyme that specifically cutes the sequence AAGCTT

Question 27

DNA migration picture - MODY2

Answer 27