Lecture 17 - how do genetic differences lead to disease

Question 1

what occurs in translation initiation

Answer 1

1. small ribosomal subunit binds to mRNA
2. large ribosomal subunit completes the initiation complex

Question 2

what occurs in elongation

Answer 2

1. codon recognition
2. peptide bond formation (for the amino acid chain)
3. translocation

Question 3

what occurs in termination

Answer 3

1. ribosome reaches a stop codon on mRNA
2. release factor promotes hydrolysis
3. ribosomal subunits and other components dissociate

Question 4

how does a mutation in a gene alter the function of the protein it encodes (folding etc)

Answer 4

• change to the DNA sequence means the mRNA will be different
• therefore the wrong amino acid will be made
• this can change the way the protein folds
• incorrect folding of the protein can mean it wont function

Question 5

what are the three types of mutations

Answer 5

• substitution
• deletion
• insertion

Question 6

explain the 4 steps of PCR

Answer 6

1. DNA from cells is heated to 95 degrees to seperate the DNA strands
2. it is then cooled to 65 degrees to recombine a DNA primer (short sequence that is chemically synthesised)
3. DNA is heated to 72 degrees to allow Taq DNA polymerase to copy the DNA
4. copying complete = then repeat the cycle