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Presemester DENT > Gene Expression Control I > Flashcards

Gene Expression Control I Flashcards

1
Q

What is RNA sequencing?

A

Every single RNA ina

cell is isolated from cells and sequenced

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2
Q

What is beta-actin?

A

A major component of the cell cytoskeleton and is expressed in all cells

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3
Q

What is tyrosine aminotransferase?

A

Enzyme that is only expressed in liver hepatocytes.

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4
Q

What does constitutively expressed?

A

The gene is always on

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5
Q

What can happen to genes before and after differentiation?

A

Some genes are turned on

Some genes are turned off

Some genes are constitutively expressed

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6
Q

Does RNA differences indicate protein differences?

A

No, RNA expressed in a cell does not always reflect large difference in protein expression in the cell. Proteins can be modified after they are expressed.

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7
Q

What percentage of genes are expressed in a typical human cell?

A

30 - 60%

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8
Q

What factors influence gene expression?

A

Signals:

Cell-cell contact

Hormones

Morphogens

Transcription factors

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9
Q

What are morphogens?

A

Molecules that specify cellular identity: Concentration of these is important.

Many morphogens are transcription factors

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10
Q

What are transcription factors?

A

Proteins which bind to regulatory elements of a gene. They control transcription and are often activated in response to external stimuli.

2 main catergories; general or tissue/cell specific.

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11
Q

Where in the promoter region do transcription factors bind?

A

Assembly of transcription factors and transcription machinery occurs in the TATA box.

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12
Q

What are the levels of regulation of gene expression?

A

DNA -> RNA (transcription control)

RNA processing to mRNA control

mRNA transport and localization control

Translation control

mRNA degradation control

Protein activity control

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13
Q

What is the primary means of regulating gene expression?

A

Transcriptional control.

cis-acting control elements regulate transcription

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14
Q

What are promoters?

A

Sequences that determine the transcription start site and direct binding of RNA pol II

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15
Q

What do enhancers and repressors do?

A

They help regulate a particular gene and are often tissue specific and function only in specific diffrentiated cell types

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16
Q

Where are promoters located?

A

Near start site (5’ end)

17
Q

Where are enhancers located?

A

Anywhere near the gene and may also be many kb away

18
Q

What do cis-acting control elements do?

A

They regulate transcription

19
Q

What is combinatorial control?

A

Eukaryotic genes are controlled by combinations of transcription factors binding to DNA binding sites in the promoter this form of control is called combinatorial control

20
Q

What is combinatorial control of gene expression dependent on?

A

DNA sequences present

TFs present

Interactions between regulatory proteins.

21
Q

How do transcriptional elements and bound TFs interact with the RNA pol?

A

DNA/TF complex loops back to interact with the TATA factors. They stabilize the binding between RNA pol and the TATA box.

22
Q

What do TFs do to transcription initiation?

A

They serve to increase or decrease the rate of transcription initiation.

23
Q

What are some examples of transcription factors?

A

Leucine zipper proteins (2 alpha helices that bind major group of DNA that it is specific to)

Helix-Loop-Helix proteins (Bind directly to a specific sequence of DNA like leucine zipper (using 2 alpha helices)

24
Q

What domains do regulatory proteins commonly have?

A

Domain that recognizes correct DNA promoter or enhancer element

Domain that interacts with one or more proteins of the initiation complex

Domain that interacts with TFs bound to their cis-element

Domain that influences chromatin remodelling

Domain that acts as a sensor of conditions within or outside the cell

25
Q

How do transcription factors work together (cooperative binding)?

A

Sometimes they only have an important effect on transcription when they are combined together. (eg NFAT and AP1 cooperative binding)

26
Q

How do glucocorticoid receptors work?

A

When hormone binds to its receptor, the TFs bounds to the receptor can be translocated to the nucleus.

27
Q

How does chromatin environment affect transcription?

A

Tightly packaged regions are not expressed and are called heterochromatin

Non-tightly packaged regions are expressed and are called euchromatin.

28
Q

What does nuclease (DNase I) do?

A

Digests DNA dependent on access to the DNA and chromatin structure. DNase I sensitivity depends on gene activity (more active = more digestion)

Presemester DENT (16 decks)

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