Molecular

Question 1

To form a nucleosome the DNA loops ___ times around the histone octamer

Answer 1

twice

Question 2

What stabilizes the chromatin fiber?

Answer 2

H1 binding to the nucleosome and linker DNA

Question 3

What gives the DNA its negative charge?

Answer 3

Phosphate

Question 4

What give the DNA its positive charge

Answer 4

1. Lysine

2. Arginine

Question 5

What phase in the cell cycle where DNA and histone synthesis occurs?

Answer 5

S phase

Question 6

___ refers to the inactive X chromosomes that is visible on the periphery

Answer 6

Barr Bodies

Question 7

Between hetrochromatin and euchromatin, which is transcriptionally active?

Answer 7

Euchromatin

less condensed

Heterochromatin = highly condensed

Question 8

What is the role of CpG islands in gene transcription?

Answer 8

It silences the gene transcription by methylation of DNA

Methylation = mute
Acetylation = active

Question 9

What is the effect of histone deacetylation in gene transcription?

Answer 9

decreases transcription

Question 10

What are the amino acids necessary for purine synthesis?

Answer 10

1. Glycine
2. Aspartate
3. Glutamine

Question 11

Site of synthesis of leading and lagging strands

Answer 11

replication fork

Question 12

What elongates the leading strand in prokaryotes by adding deoxynucleotide to the 3’ end

Answer 12

DNA polymerase III

5’ to 3’ synthesis
3’ to 5’ proofreading

Question 13

What enzyme found in prokaryotes degrades RNA primer and replaces it with DNA?

Answer 13

DNA polymerase I

Question 14

What enzyme adds DNA tot eh 3’ end of the chromosome to avoid loss of genetic material with every duplication

Answer 14

Telomerase

Question 15

[Single nucleotide substitution]

nucleotide substitution codes for same amino acid

Answer 15

Silent mutation

Usually in the 3rd position of codon

Question 16

[Single nucleotide substitution]

nucleotide substitution results in changed amino acid

Answer 16

Missense mutation

Question 17

[Single nucleotide substitution]

nucleotide substitution results in stop codon

Answer 17

Nonsense mutation

Question 18

[Single nucleotide substitution]

deletion or insertion of a number of nucleotides not divisible by 3

Answer 18

frameshift mutation

Misreading of all nucleotides; duchenne, tay sachs

Question 19

[Single nucleotide substitution]

retained intron in mRNA resulting to protein with impaired or altered function

Answer 19

splice site mutation

dementia, epilepsy, beta thalassemia, gaucher disease, marfan

Question 20

[Diagnose]

____ refers to inability to repair DNA pyrimidine dimers caused by UV exposure

Answer 20

xeroderma pigmentosus - defect in nucleotide excision repair

Question 21

DNA repair defect in Lynch Syndrome

Answer 21

Mismatch repair

Question 22

DNA repair defect in ataxia-telangectasisa

Answer 22

nonhomologous end joining