Molecular

Question 1

What are the purines?

Answer 1

• Adenine

- Guanine

Question 2

What are the pyrimidines?

Answer 2

• Cytosine
• Thymine
• Uracil

Question 3

How many times does DNA loop around histone?

Answer 3

Twice

Question 4

What does H1 act as?

Answer 4

A histone linker

Question 5

During what phase does DNA and histone synthesis occur?

Answer 5

S phase

Question 6

What are Barr Bodies?

Answer 6

Inactive X chromosomes

Question 7

What gives DNA a negative charge?

Answer 7

Phosphate

Question 8

What amino acids give histones a positive charge?

Answer 8

• Lysine

- Arginine

Question 10

What does histone acetylation do?

Answer 10

• Increases transcription
• Removes histone’s positive charge, relaxing coiling
• Attaches to lysine

Question 11

What sequence of genes represses transcription?

Answer 11

CpG islands (C, G)
- Methyl group attaches to Cytosine

Question 12

What processes involve DNA methylation?

Answer 12

• Aging
• X chromosome inactivation (lyonization)
• Carcinogenesis
• Genomic imprinting
• Transposable element repression

Question 13

What disease is thought to be due to dysregulated acetylation?

Answer 13

Huntington’s

Question 14

What do nucleosides lack?

Answer 14

A phosphate group

Question 15

How many rings do purines (A, G) contain?

Answer 15

2

Question 16

How many rings do pyrimidines (CUT) contain?

Answer 16

1

Question 17

How many H bonds do the bases have?

Answer 17

• C-G bond has 3 (higher melting point)

- A-T bond has 2

Question 18

What does deaminated Cytosine become?

Answer 18

Uracil

Question 19

What does deaminated Adenine become?

Answer 19

Hypoxanthine

Question 20

What does deaminated Guanine become?

Answer 20

Xanthine

Question 21

What does deaminated 5-methylcytosine become?

Answer 21

Thymine

Question 22

What does methylation of uracil make?

Answer 22

Thymine

Question 23

What amino acids are necessary for purine synthesis?

Answer 23

• Glycine
• Aspartate
• Glutamine

Question 24

What makes up a nucleoside and a nucleotide?

Answer 24

• Nucleoside = base + sugar (ribose/deoxyribose)

- Nucleotide = base + sugar + phosphate

Question 25

Why does the C-G bond have a higher melting point than the A-T bond?

Answer 25

C-G has 3 Hydrogen bonds whereas A-T has 2

Question 26

What do antibodies target in drug-induced lupus?

Answer 26

Histones (in >95% of cases)

Question 27

What drugs are responsible in drug-induced lupus?

Answer 27

• Hydralazine (BP and HF drug, vasodilator)
• Procainamide (ant-arrhythmic)
• Isoniazid (anti-TB)

HIP

Question 28

What is the source of Nitrogen in humans?

Answer 28

Amino acids (usually meats/protein rich foods)

Question 29

What kind of molecule is DNA?

Answer 29

Polymer (made up of individual nucleotides [monomers])

Question 30

The Nucleosides are called:

Answer 30

Pyrimidines: (-idine)
Cytidine, Uridine, Thymidine
Purines: (-sine)
Adenosine, Guanosine

Question 31

The bases are called:

Answer 31

Pyrimidines:
Cytosine, Uracil, Thymine

Purines:
Adenine, Guanine

Question 32

How many phosphate groups do the nucleotides have when incorporated into DNA?

Answer 32

3 (triphosphate form)

• They are synthesised as monophosphates then converted to triphosphates
• The 2 phosphates are cleaved off once the nucleotide is attached
• E.g Deoxyadenosine Triphosphate

Question 33

What can unmethylated CG islands cause?

Answer 33

Immune response

Question 34

What is the purpose of methylation in bacteria?

Answer 34

Protection from bacteriophages

- They can methylate both A and C

Question 35

What do the antibodies target in classic lupus?

Answer 35

The dsDNA molecules (drug induced it id the histones)

Question 36

What substances are required to make Purines (A, G)?

Answer 36

• Glycine (2C, 1N)
• Aspartate (1N)
• Glutamine (2N)
• 2x N10-Fomyl-tetrahydrofolates (2C)
• CO2 (1C)

Question 37

What substances are required to make up pyramidines (C, U, T)?

Answer 37

• Aspartate (3C, 1N)

- Carbamoyl phosphate (1N, 1C)