Molecular Basis Of Inheritance

Question 1

Labels used In Hershey and chase experiments

Answer 1

35S; 32P

Question 2

Purines, number of carbons

Answer 2

G A 9

Question 3

Pyrimidines

Answer 3

C T 6

Question 4

Side chains in bases

Answer 4

Carbonyl
Amine
Methyl

Question 5

What’s in a nucleoside

Answer 5

Sugar + base

Question 6

What’s a nucleotide

Answer 6

Sugar + base + phosphate

Question 7

DNA measurements

Answer 7

10 nucleotides per turn
0.34nm nucleotide distance
2nm diameter

Question 8

Number of H bonds between AT, CG

Answer 8

AT=2

CG=3

Question 9

Human genome composition

Answer 9

Protein. Coding= 1.1%
Transposon= 4%
Unique sequences= 44%
Heterochromatin= 6.6%

Question 10

Transposon repeats

Answer 10

Can move to random location
LINES (Long interspersed elements): L1 is 6,5k Bp Long. Mostly inactive. When L1 transposes to factor 8 gene on X chromosome-> hemophilia A

SINES: alu repeat is 160 bp long

Question 11

Heterochromatin

Answer 11

Very compact
Many high copy number tandem repeats
Genetic fingerprinting/forensic testing

Question 12

What’s snrna

Answer 12

Small nuclear rna

Combines with proteins to form small ribonucleoprotein particles-> mrna splicing

Question 13

X inactivation. When

Answer 13

X inactivation centre has XIST gene-> transcribed to a ncrna -> heterochromatin spreads from inactivation centre-> silencing of X chromosome-> twice amount of transcription isn’t observed
Early in embryogenesis

Question 14

2 X inactivation linked diseases

Answer 14

1. Anhidrotic ectodermal dysplasia (patches of skin without sweat glands)
2. Red green colour blindness (males are completely blind; females in patches)

Question 15

Mirna formation

Answer 15

Mirna gene transcribed -> hairpin precursor mirna-> export into cytoplasm-> nuclease processes it-> single strand of mirna-> base pairs with coding mrna-> translational repression/deadenylation

Question 16

Mitochondrial genome

Answer 16

MtDNA 
RRNA 
tRNA 
No introns 
No repetitive DNA

Question 17

Mitochondrial diseases

Answer 17

MELAS (myopathy, encephalopathy, lactic acidosis, stroke like episodes)
LHON (leber’s hereditary optic neuropathy)