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MCBM Part 1 > Kandpal - Chromatin Structure and Transcription > Flashcards

Kandpal - Chromatin Structure and Transcription Flashcards

1
Q

What are Eukaryotic gene expressions regulated by?

A

Chromosome structure

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2
Q

Can gene’s be turned on and off?

A

Yes, by switching between 2 alternative structures of a chromosome.

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3
Q

What is another name for organized structure of a chromosome?

A

Chromatin

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4
Q

If DNA is inactive, what is another name?

A

Heterochromatin

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5
Q

What is another name for an active sequence?

A

Euchromatin

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6
Q

How many units of an octamer of histones are required?

A

146 bp

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7
Q

What is the suffix for short arm metaphase chromosome?

A

P

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8
Q

What is the suffix for a long arm metaphase chromosome?

A

Q

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9
Q

How man turns of DNA does a nucleosome have?

A

2 turns

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10
Q

What is the shape of a nucleosome?

A

Flat disk

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11
Q

Name the 4 core histones.

A

H2A, H2B, H3 and H4

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12
Q

Out of the core histones, which ones are most conserved?

A

H3 and H4. While H2A and H2B show variation

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13
Q

Out of the 4 core histones which one is the linker histone?

A

H1

Note: Also the compacter.of DNA

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14
Q

Name the 3 histone modifiers.

A
  1. Acetylation
  2. Methylation
  3. Phosphorylation
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15
Q

During the histone modification, which one adds and which one removes acetyl?

A

HAT’s (HIstone Acetyl Transferases) for addition.

HDAC’s (Histone Deacetylase Complexes) for removal.

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16
Q

During the histone modification, which one adds methyl and removes methyl?

A

Histone methyl transferase for addition.

Histone demethylases removes methyl

17
Q

What reduces the positive charge of Lysine?

A

Acetylation - loosening of chromatin structure

18
Q

What is the name of modification of histones which occur in different combinations?

A

Histone Code

19
Q

When decondensation of Interphase of chromosomes occurs, what portion of the chromosome becomes highly expressed?

A

The loop gets exaggerated.

20
Q

Which phase of interphase condenses chromosomes?

A

Metaphase

21
Q

What phase decondenses chromosomes?

A

Interphase

22
Q

Is epigenetic always controlled by DNA sequence?

A

No. It never is.

23
Q

What is epigenetic control brought about by?

A

Modification of DNA bases and histones.

24
Q

What is histone modification?

A

It is acetylation and found in active chromatin

25
Q

T or F. Methylation of cytosines in CpG dinucleotides of promoter truns off the promotor.

A

True.

26
Q

During what time of fertilization does inactivation occur?

A

Within 2 weeks of fertilization. 500 to 1000 cells

27
Q

What type of RNA does inactivation mediated by?

A

Xist RNA (Inactivates 1 chromosome)

28
Q

T or F. Majority of genes are expressed equally.

A

True

29
Q

What is called when a gene is not expressed?

A

Imprinting.

30
Q

What is PWS?

A

Prader-Willi Syndrome
Mild to moderate mental retardation
Hypotonia and poor feeding in infancy
Short stature, small hands and feet and small external genitalia
Compulsive overeating and massive obesity
Microdeletion of 15q11-q13
Deletion inherited from father (maternal allele of the gene is imprinted).

31
Q

What is AS?

A 
Angelman Syndrome
Severe mental retardation with absence of speech
Seizures
Jerky gait
Large mouth with a prominent tongue
Happy disposition and excessive laughter
Microdeletion of chromosome 15q11-q13
Deletion inherited from mother (paternal copy of the gene is imprinted).
32
Q

What is MECP2 and is its function?

A

Methyl cytosine binding protein encoding gene

33
Q

What is Rett Syndrome?

A

It is a X-linked disorder limited to females.

Some causes are inability to speak and walk

34
Q

What does DNMT3 stand for and what kind of syndrome is it?

A

De Novo Methyltransferase. It is a immunodeficiency, chromosome instability and facial anomalies

35
Q

What occurs when there is a mutation in ATRX?

A

Mental retardation, urogenital abnormalities and alpha thallasemia.

MCBM Part 1 (29 decks)

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