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MD1 Reproduction > Regulation of Gene Expression > Flashcards

Regulation of Gene Expression Flashcards

1
Q

Which type of chromatin is transcriptionally active and inactive?

A 
Heterochromatin = inactive
Euchromatin = active
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2
Q

What is gene expression?

A

Production of functional and active gene products

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3
Q

What is constitutive gene expression?

A

Made by all cells at all times
Often called housekeeping genes
Expression constant

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4
Q

What is regulated gene expression?

A

Time, place, amount, in response to signals

Under very tight control

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5
Q

What kind of processing does a primary transcript undergo?

A 
Addition of
- 5' cap
- Poly(A) tail
Excision of introns
Splicing of exons via spliceosome
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6
Q

What does the 5’ cap do?

A

Directs mRNA to ribosome

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7
Q

What does the poly(A) tail do?

A

Stabilises transcript

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8
Q

Are some non-coding RNAs involved in primary transcript splicing?

A

Yes

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9
Q

Are mutations or variants spliced the same as the normal RNA?

A

No, they produce alternative splicing

Sometimes this is on purpose, sometimes they have adverse effects

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10
Q

What is a spliceosome?

A

Large ribonucleoprotein complex > splcies primary transcripts to remove introns

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11
Q

Does transcription only occur at the promoter regions?

A

No

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12
Q

Where can some RNAs be transcribed from, if not from promoter regions?

A

Introns

Intergenic regions

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13
Q

What is chromatin?

A

DNA + RNA + protein

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14
Q

When is chromatin present?

A

Only during cell division

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15
Q

What must happen to the chromatin for transcription to occur?

A

Must go from closed to open conformation

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16
Q

What proteins have an important role in altering the conformation of chromatin?

A

Histone proteins

17
Q

What is the most typical chemical modification that happens to DNA?

A

Methylation

18
Q

What does DNA methylation change?

A

Conformation of DNA

19
Q

What is nucleosome occupancy?

A

Density of nucleosome varies along DNA

20
Q

True or false: local location of DNA in nucleus influences its conformation

A

True

21
Q

What does chromatin remodelling require?

A

Chemical modification (epigenetic markers) to histones and DNA

22
Q

What effect does DNA methylation have on transcription?

A

Generally “locks in” transcriptional inactivity

23
Q

How does DNA methylation happen to a new DNA strand?

A

Large proportion of cytosines in CG adjacent methylated
DNA replication > new DNA strands
New DNA strands initially lack methyl groups
Original pattern of DNA methylation transmitted to daughter cells

24
Q

What are CpG-rich islands associated with?

A

5’ region of genes

25
Q

What does gene expression or silencing seem to be more related to in terms of methylation?

A

Methylation status of other CpGs, not CpG islands

26
Q

What is hyper-acetylation of histones associated with in terms of transcription?

A

Transcriptionally active

27
Q

What is hypo-acetylation of histones associated with in terms of transcription?

A

Transcriptionally silent

28
Q

What are writer enzymes?

A

Add on chemical modifications to chromatin

29
Q

What are eraser enzymes?

A

Remove chemical modifications to chromatin

30
Q

What are reader enzymes?

A

Read chemical markers on chromatin, and allow other proteins to bind

31
Q

How can transcription be regulated in the gene itself?

A

Promoters major on-off switches
Looping of DNA
Direct interactions with other DNA sequences, non-coding RNAs, and trans-acting proteins

32
Q

Do genes only have one promoter?

A

No, many genes have 1+ promoter

33
Q

What can alternative splicing of different exons lead to?

A

Different protein products, often tissue specific

34
Q

What are some examples of non-coding RNAs that regulate gene expression?

A 
Long non-coding RNAs (lncRNAs)
Short interfering RNAs (siRNAs)
Micro RNAs (miRNAs)
35
Q

What are long non-coding RNAs?

A

Long enough to fold over and associate with themselves, creating secondary structure

36
Q

What are short interfering RNAs?

A

Sub-category of long RNAs
Complementary to mRNA
Degrade mRNA

37
Q

What are micro RNAs?

A

Not completely complementary to mRNA
Binding feeds back to ribosome and represses its activation
Reduction of gene expression

MD1 Reproduction (11 decks)

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