Genetics

Question 1

In what direction is DNA read?

Answer 1

5’ to 3’

Question 2

what is X inactivation

Answer 2

The process by which one of the copies of the X chromosome present in female mammals is inactivated. It prevents females from having twice as many X chromosome gene products as males, who only possess a single copy of the X chromosome. (dosage compensation)

Question 3

what is a TATA box?

Answer 3

RNA polymerase cannot recognise the transcription site alone, so must bind to the TATA box ( a specific sequence) so it knows where to start transcribing.

Question 4

Describe PCR

Answer 4

1. DNA is heated to 95 degrees to breaking the hydrogen bonds, unwind it into 2 strands.
2. Temp is lowered to 55 degrees to allow primers to anneal.
3. temp increased to 70 degrees so TAQ polymerase can bind
4. the nucleotides bind.
5. continues until you have run out of nucleotides

Question 5

Describe Sangar sequencing

Answer 5

1. PCR
2. add ddNTPs with fluorescent markers to create DNA strands of different lengths
3. gel electrophoresis- separate the strands according to length (small ones move further down) so the DNA sequence can be determined