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Physiology > LECTURE 30 > Flashcards

LECTURE 30 Flashcards

1
Q

What are commonalities among almost all genes?

A

Transcriptional start site (TSS), promoter region, axons and introns, 3’ UTR

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2
Q

What are the basic levels of transcriptional regulation?

A
  • binding of transcription factors to 5’ promoter region
  • binding of RNA polymerase II to the TSS to initiate transcription
  • epigenetics
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3
Q

What is epigenetics?

A

A heritable chance in the absence of change in the DNA sequence

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4
Q

What is DNA methylation?

A

The addition of a methyl group to the cytosine base of a CpG dinucleotide

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5
Q

Where does DNA methylation often occur?

A

At the promoter region of genes, areas rich in CG base pairs

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6
Q

What is the outcome of DNA methylation?

A

Repression of transcription

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7
Q

How is the methyl group transferred?

A

SAM (from folate and serene) through DNMT - add methyl group - SAH

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8
Q

What facilitates DNA methylation?

A

DNA methyl transferases: DNMT1, DNMT3a, DNMT3b

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9
Q

What is DNA demethylation facilitated by?

A

TET1, TET2, TET3

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10
Q

What is the demethylation reaction dependent on?

A

The presence of alpha ketoglutarate (intermediate of krebs cycle) and the release of succienate - facilitated by TET - transcription can occur

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11
Q

Where is serene from and what does it do?

A

From glycolysis, enters 1 carbon cycle and produces SAM - DNA methylation

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12
Q

What genes are expressed more in proliferating and quiescent satellite cells?

A

P: DNMT
Q: TET

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13
Q

What are histones made up of?

A

H2A, H2B, H3, H4, tail which is subject to post translational modification

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14
Q

What is histone methylation?

A

The addition of a methyl group to a specific lysine (or arginine) amino acid in the histone tail – often results in the formation of tightly packed chromatin, which prevents transcription factor binding and inhibits transcription

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15
Q

What is the histone nomenclature?

A

Histon + amino acid + (methyalted/acetylated)

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16
Q

What is histone methylation facilitated by?

A

Histone methyl transferases (HMTs) - facilitate SAM - SAH

17
Q

What facilitates histone demethylation?

A

Lysine demethylases (KDMs) - LSD and JHDM families

18
Q

What does JHDM do?

A

Converts alpha ketoglutarate to succinate for histone demethylation

19
Q

What does LSD do?

A

Converts FAD+ to FADH for histone demethylation

20
Q

What happens if there is increased folate/serine?

A

Increased carbon cycle, increased SAM, increased DNA and histone methylation, transcription repressed

21
Q

What happens if there is increased pyruvate?

A

Increased TCA, increased alpha ketoglutarate, increased TET and JHDM, demethylation, transcription can occur

22
Q

What happens with histone methylation in satellite cells?

A
  • Increased HMT as cells move from Q to P

- Decreased expression of methylated marked genes (methylation represses transcription and gene expression)

23
Q

What is histone acetylation?

A

The addition of an acetyl group to a specific lysine amino acid in the histone tail – often results in the formation of loosely packed chromatin, which allows transcription factor binding and promotes transcription

24
Q

What is histone acetylation facilitated by?

A

HATs - convert citrate to acetyl CoA

25
Q

When is HAT at high levels?

A

When the cell is undergoing identity changes

26
Q

What facilitates histone deacytylation?

A

HDAC, SIRT

27
Q

What does HDAC do?

A

Converts water to acetate for deacytylation

28
Q

What does SIRT do?

A

Converts NAD+ (from ETC) to NAM for deacytylation

29
Q

What does deacytylation cause?

A

Repression of transcription

30
Q

What does glycolysis cause?

A

Increase use of NAD+, so lack of NAD+ available for SIRT - decrease deacytylation (more transcription)

31
Q

When does the satellite cell become glycolytic?

A

When it becomes active and proliferative (oxidative in quiescence) - associated with decreased NAD+ and increased acetylation

Physiology (12 decks)

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