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Bio 1A03 > Eukaryotic Transcriptional Regulation > Flashcards

Eukaryotic Transcriptional Regulation Flashcards

1
Q

Different embryonic cells will have different fates depending on the _____ exchanged and which _____ are switched on or off

A

signals, genes

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2
Q

____________ creates various cell types that can be organized into _________

A

Gene regulation, tissue types

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3
Q

Although cells may have the same ________ gene regulation differences can lead to altered _________

A

genomes, proteomes

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4
Q

What are transcription factors?

A

Proteins that bind to specific DNA sequences and control transcription, and determine cell type pathways

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5
Q

What in dividing embryos leads to stem cells becoming speciallized cells?

A

Gene expression patterns and regulation, and extracellular cues

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6
Q

By controlling which genes are _____ along the chromosome, there are many _______ types and ______ found in specific tissues

A

Active, cell types, specific proteins

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7
Q

How to eukaryotes control gene expression (general)

A

Use of promoters and enhancers for each specific gene; no operons

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8
Q

How does tightly wound heterochromatin affect whether a gene is expressed?

A

Genes within tightly wound heterochromatin are usually not expressed unless it is unwound from the histone proteins

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9
Q

What is a nucleosome?

A

8 histone proteins

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10
Q

Chromatin must be unwound through _________ __________ when a _________ protein or _________ __________ is able to bind to an accessible _______ site, leading to further chromatin remodelling

A

Chromatin remodelling, activator, transcriptional factor, enhancer

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11
Q

How is DNA wound around histones?

A

Interactions between negatively charged phosphates in DNA and positively charged histone tails

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12
Q

What does the coactivator enzyme histone acetyltransferase do during chromatin remodelling?

A

Reacts with activator proteins, attaches acetyl groups to lysine amino acids along the positive tails , reducing the positive charge and loosening them so transcription factors can bind

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13
Q

What other chemical modificaitons can alter histone tails?

A

-Methylation of lysine and arginine
-Phosphorylation of serine and threonine

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14
Q

Acetylation and methylation with a single methyl group leads to…

A

Transcriptional activation

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15
Q

Methylation with three methyl groups leads to…

A

repression of transcription

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16
Q

What are the 4 transcriptional factor DNA binding structures?

A

-basic-helix-loop-helix
-helix-turn-helix
-zinc finger
-leucine zipper regions

17
Q

Most transcriptional factors have a _______________ that fits within major ______ of DNA due to molecular interactions between amino acids in the alpha helix and the ______________ of nitrogenous bases

A

alpha-helical domain, grooves, functional group

18
Q

What happens when a strong enough interaction is made by transcription factors?

A

TF assumes a conformaiton that allows the recruitment of other transcription factors, RNA polymerase, and activation of transcription at the target gene

19
Q

What are the specific sequences required to initiate transcription at promoter regions?

A

Cissequences

20
Q

What is found in the core promoter?

A

TATA box, BRE region, and transcriptional start sites

21
Q

What usually recognizes the TATA box?

A

TATA binding protein subunit of the transcription factor TFIID

22
Q

What binds the BRE region?

A

TFIIB general transcription factor

23
Q

What is the purpose of the TATA and BRE binding transcription factors?

A

Assists with the assembly of the transcription initiation complex

24
Q

How do enhancer region bound transcription factors contribute to RNA polymerase recruitment and initiation?

A

-Facilitates formation of the transcription complex
-Interact witht he basal machinery at the promoter to enhance transcription
-When DNA loops, they are connected to the proteins at the core promoter

25
Q

What is the function of adapter/mediator proteins?

A

They connect proteins bound the the enhancer region withe proteins at the core promoter, so they can interact with RNA polymerase and basal transcriptional machinery at the core promoter

26
Q

In eukaryotes, what are the sequences that bind transcriptional repressors and halt transcription called?

A

Silencer regions

27
Q

_________________ differentiate into red blood cells that contain ___________ that can bind O2

A

Blood cell progenitors, haemoglobin

28
Q

How does blood cell progenator gene activation differ in fetuses and adults?

A

-Both have 2 alpha-globin proteins making up half their tetrametric haemoglobin proteins
-Fetuses have 2 gamma-globin proteins
-Adults have 2 beta-globin proteins

29
Q

How does gamma-globin differ from beta-globin?

A

Gamma-globin can bind O2 better, allowing fetuses to sequester enough oxygen in the womb

30
Q

How is the beta globin gene inhibited in fetuses?

A

The chromatin is wound around the beta globin gene, while the gamma-globin gene is left open

31
Q

How is the gamma globin gene repressed in adults?

A

Transcription factors can silence or repress gamma-globin and activate beta-globin

32
Q

What is a CpG island and how can it inhibit transcription?

A

A string of cytosine and guanine

The methylation of the cytosines in a CpG island near promoter sequences can inhibit transcription by preventing DNA binding proteins from recognizing and binding the promoter sequence

33
Q

The methylation state of promoters is _____, channging to ________/____________ cues

A

dynamic, environmental/developmental

34
Q

Methylaiton state is _________ from mother cells to daughter cells

A

heritable

35
Q

Which protein can only bind to methylated DNA? What do they do?

A

Histone deacetylases

Bind to methylated DNA and promote removal of acetyl groups from neighbouring histones

36
Q

What does the deacetylation of histones do?

A

-Allows nucleosomes to reassemble
-Can lead to masking enhancer and promoter sequences, repressing transcription

37
Q

Eukaryotic chromatin is wound in a default _____ conformation, genes are only transcribed when chromatin is remodelled to expose ___________

A

off, promoter sequences

38
Q

Prokaryotyes have a default _____ conformation

A

on

Bio 1A03 (15 decks)

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