Molecular Flashcards

1
Q

What are the purines?

A
  • Adenine

- Guanine

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2
Q

What are the pyrimidines?

A
  • Cytosine
  • Thymine
  • Uracil
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3
Q

How many times does DNA loop around histone?

A

Twice

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4
Q

What does H1 act as?

A

A histone linker

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5
Q

During what phase does DNA and histone synthesis occur?

A

S phase

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6
Q

What are Barr Bodies?

A

Inactive X chromosomes

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7
Q

What gives DNA a negative charge?

A

Phosphate

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8
Q

What amino acids give histones a positive charge?

A
  • Lysine

- Arginine

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9
Q
A
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10
Q

What does histone acetylation do?

A
  • Increases transcription
  • Removes histone’s positive charge, relaxing coiling
  • Attaches to lysine
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11
Q

What sequence of genes represses transcription?

A
CpG islands (C, G)
- Methyl group attaches to Cytosine
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12
Q

What processes involve DNA methylation?

A
  • Aging
  • X chromosome inactivation (lyonization)
  • Carcinogenesis
  • Genomic imprinting
  • Transposable element repression
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13
Q

What disease is thought to be due to dysregulated acetylation?

A

Huntington’s

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14
Q

What do nucleosides lack?

A

A phosphate group

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15
Q

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

A

2

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16
Q

How many rings do pyrimidines (CUT) contain?

17
Q

How many H bonds do the bases have?

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

- A-T bond has 2

18
Q

What does deaminated Cytosine become?

19
Q

What does deaminated Adenine become?

A

Hypoxanthine

20
Q

What does deaminated Guanine become?

21
Q

What does deaminated 5-methylcytosine become?

22
Q

What does methylation of uracil make?

23
Q

What amino acids are necessary for purine synthesis?

A
  • Glycine
  • Aspartate
  • Glutamine
24
Q

What makes up a nucleoside and a nucleotide?

A
  • Nucleoside = base + sugar (ribose/deoxyribose)

- Nucleotide = base + sugar + phosphate

25
Why does the C-G bond have a higher melting point than the A-T bond?
C-G has 3 Hydrogen bonds whereas A-T has 2
26
What do antibodies target in drug-induced lupus?
Histones (in >95% of cases)
27
What drugs are responsible in drug-induced lupus?
- Hydralazine (BP and HF drug, vasodilator) - Procainamide (ant-arrhythmic) - Isoniazid (anti-TB) HIP
28
What is the source of Nitrogen in humans?
Amino acids (usually meats/protein rich foods)
29
What kind of molecule is DNA?
Polymer (made up of individual nucleotides [monomers])
30
The Nucleosides are called:
Pyrimidines: (-idine) Cytidine, Uridine, Thymidine Purines: (-sine) Adenosine, Guanosine
31
The bases are called:
Pyrimidines: Cytosine, Uracil, Thymine Purines: Adenine, Guanine
32
How many phosphate groups do the nucleotides have when incorporated into DNA?
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
33
What can unmethylated CG islands cause?
Immune response
34
What is the purpose of methylation in bacteria?
Protection from bacteriophages | - They can methylate both A and C
35
What do the antibodies target in classic lupus?
The dsDNA molecules (drug induced it id the histones)
36
What substances are required to make Purines (A, G)?
- Glycine (2C, 1N) - Aspartate (1N) - Glutamine (2N) - 2x N10-Fomyl-tetrahydrofolates (2C) - CO2 (1C)
37
What substances are required to make up pyramidines (C, U, T)?
- Aspartate (3C, 1N) | - Carbamoyl phosphate (1N, 1C)