fundamental molecular lecture 4 taste lab

Question 1

what is PTC?

Answer 1

-PhenylThioCarbimide
- has a similar chemical group found in brassica vegetables
- PTC tastes bitter to around 70% of the population

Question 2

what is the inability to taste PTC?

Answer 2

A genetic trait that varies in the human population

Question 3

what is the bitter taste process?

Answer 3

TAS2R38encodes for a protein receptor that mediates the perception of bitterness through a G protein-coupled second messenger pathway ;

Variations in the gene sequence leads to ‘non taster’ or ‘taster’ phenotypes;

Sequencing identified three nucleotide positions of TAS2R38 that vary within the human population— 3 SNPs

Question 4

what is the band size analysed from the SNP in the TAS2R38 gene?

Answer 4

785 with taster C and non taster T

Question 5

what are the genotypes for weak, strong and non taster?

Answer 5

non tasters- tt
weak tasters- Tt
strong tasters- TT

Question 6

what are the temperatures for the stages of PCR?

Answer 6

denaturation= 94oC
annealing= 50-60oC
extension= 72oC

Question 7

What goes into a PCR?

Answer 7

-Template to be amplified (genomic DNA from buccal swab)
-Forward and reverse primers
-Taq DNA polymerase
-dNTPs
-Buffer tomaintainpH and provide Mg2+

Question 8

What do restriction endonuclease do?

Answer 8

Restriction enzymes cut DNA at a SPECIFIC nucleotide sequence called a restriction site

The Fnu4H1 restriction enzyme uses GCNGC recognition site
It only digests the TAS2R38 gene at this site

Remember the TAS2R38 gene contains single nucleotide polymorphisms
You may be GCTGC and/or GTTGC at position 785
The Fnu4H1 may or may not digest the DNA in the given samples

Question 9

what are the band sizes of genotypes?

Answer 9

tt= 312bp
Tt= 312, 206 and 106bp
TT= 206, 106bp