Lecture 4

Question 1

define polymorphism.

Answer 1

• this is a variation in the common DNA sequence that occurs and is sustained within a population at a frequency that is higher than that of an average mutation.
• found in more than 1% of the population

Question 2

what are the five types of polymorphisms?

Answer 2

1) SNP (single nucleotide polymorphism)
2) RFLP (restriction fragment length polymorphism)
3) VNTR (Variable Number Tandem Repeat)
4) SSR (Simple Sequence Repeat)
5) CNV’s (Copy Number Variants)

Question 3

what is the difference between an SNP and a point mutation?

Answer 3

• SNPs occur at a higher frequency

- SNPs have little to no affect on phenotype

Question 4

What is a RFLP and what is the result?

Answer 4

(restriction fragment length polymorphism)

• basically an SNP within an enzyme restriction site
• results in longer fragment cut by restriction enzyme

Question 5

what are microsatellites?

Answer 5

• another name for SSR

- tandem repeated sequences 1-6 nucleotides long

Question 6

what is the most useful group of polymorphic markers for gene mapping and personal identification?

Answer 6

• SSR aka microsatellites

Question 7

what is the difference between VNTR and SSR?

Answer 7

• VNTR are usually longer repeated sequences (10-100bp vs 1-6bp)
• minisatellite vs microsatellite

Question 8

what is a CNV?

Answer 8

(copy number variants)

- deletion or duplication of around 50kb to 12Mb

Question 9

what is meant by “de novo”?

Answer 9

“possessed by neither parent”

Question 10

how are CNVs caused?

Answer 10

• usually unequal crossing over during meiosis or they are inherited

Question 11

what is the mutation that results in sickle cell anemia?

Answer 11

• GAG to GTG
• Glutamic Acid to FUCKING valine
• hydrophillic hemoglobin to hydrophobic hemoglobin

Question 12

how many variants do RFLPs have?

Answer 12

2, present or absent

Question 13

how many variants do SNP’s have?

Answer 13

4, A, T, G, C

Question 14

what is the normal function of P-450?

Answer 14

• metabolism of xenobiotics and toxic compounds in the liver
• acts as hydroxylases and methyl oxidases
• primary enzyme in metabolism of drugs

Question 15

why is the CYP2D6 enzyme important?

Answer 15

• responsible for metabolizing 20% of drugs in the liver.

- gene expression that is too great results in ineffective drugs and too slow will result in toxicity.

Question 16

why is the CYP2C9 enzyme important?

Answer 16

• metabolizes 16% of drugs

- used to clear coumadin (Warfarin) which treats blood clotting in thrombophilia

Question 17

why is the CYP2C19 enzyme important?

Answer 17

• converts clopidogrel (Plavix) into the active compound (oxo-clopidogrel).

Question 18

repeat sequences account for what percent of human DNA?

Answer 18

50%