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Genetics written exam > Lecture 10 gene regulation > Flashcards

Lecture 10 gene regulation Flashcards

1
Q

How many reguletory steps are there to gene control?

A

6

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2
Q

What are the regeletary control steps in gene expression?

A

Transcriptional control, RNA processing control, RNA transport and localization control, translation control, MRNA degredation control, protein activity control

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3
Q

Where does these regeletory control steps happen?

A

Either the nucleus or cytosol

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4
Q

Which regeletory control system is most common in eukaroyotik cells?

A

Transcriptonal control

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5
Q

What are the operator in the template strand for?

A

In the 5’ to 3’ upstream direction the operator binds to the transcription factor.

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6
Q

What are the promotor in the template strand for?

A

In the 5’ to 3’ upstream direction the promotor binds to RNA polymerase to start transcription.

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7
Q

What are general transcription factors?

A

They are proteins who binds to specific sites to the DNA to activate transcription

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8
Q

What makes up the basic transcription apparatus?

A

General transcription factors, with RNA polymerase and the protein mediator multiple protein complex

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9
Q

What are activators?

A

They increase the attraction of the RNA polymerase either by changing the structure of the DNA or by interacting with subunits of the RNA polymerase.

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10
Q

What do activators do?

A

Promote and enhance the transcription of that gene sequence

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11
Q

What is an example of an activator?

A

CAP

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12
Q

What are enhancers?

A

They are sites of the DNA binding with activators to lope the DNA to bring the promotor to the initaition complex

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13
Q

What does enhancers do?

A

Enhance the transcription of that gene sequence but unlike the activators it doesn’t need to be close to that gene sequence it can even be on a different chromosome

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14
Q

What are repressors?

A

They bind to the operator and they stop the RNA polymerase from working

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15
Q

What happens if an inducer and and a repressor meets?

A

The repressor detatches from the strand and the RNA polymerase can transcribe furhter down the strand

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16
Q

What are silencers and what are their function?

A

It’s a protein that stops the RNA polymerase from binding to the DNA sequence which ends up solencing the gene sequence.

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17
Q

What do transcription regulators identify?

A

Cis regeletory sequences that are often 5-10 nucleotides long

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18
Q

Whart are DNA looping for?

A

It allows transcriptional regulators to interact with proteins assembled at the promotor

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19
Q

What is the mediator?

A

It’s a large protein that coordinates the proteins and RNA polymerase II facilitating their assemblence at the promotor

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20
Q

What do transcription factors work with?

A

Mediators, but some GTFs or RNA polymerase directly

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21
Q

How are transcription regulators binding to the cis-regulatory sequences

A

Often in clusters

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22
Q

What are some multi-subunits that often bind to transcription regulators?

A

transcription activators and transcription repressors, the most important co activator is the mediator

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23
Q

How does transcription activators work?

A

Transcription activators attract coactivators that favor
trancription initiation through nucleosome remodeling, nucleosome
removal, histone replacement, and histone modifications.
These alterations increase the accessability of DNA and facilitate the
binding of RNA polymerase II and the GTFs

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24
Q

What is transcriptional synergery?

A

Several transcription activators working together to form a higher rate of trnacription

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25
What are exons?
Protein coding DNA and RNA
26
What are introns and what happen to them during translation?
They are non coding RNA and they get spliced out q
27
What is the splicoesome and what does it do?
It cuts off introns by looping them into a circle binding on one side of the intron and then cuts it off
28
What are the ends of the mRNA called?
A 5'cap and a 3'poly A tail
29
What are exonuclesaes?
The degredation of mRNA
30
How does the cell protect the mRNA against exonuclesaes?
By the 5'cap doing a 5 to 5 linkage
31
What are some functions of the 5'cap?
Protecting against exonucleases and promoting ribosome binding as well as regulating nuclear export
32
What does the 3' poly A tail do?
It adds multiple adenenine phostphates to the tail to protect against exonucleases by acting as a buffer and prolongs the halflife of the mRNA, regulate export and act as a transcription terminater
33
How long is the 3'poly A tail?
About 250 nucleotide bases long
34
What is RNA editing?
It deletes, inserts and substitutes different nucleotide bases with various different enzymes
35
What is ADAR?
It's an enzyme part of RNA editing that converts adenosine to inosine
36
What is CDAR?
It's an enzyme that converts cytosine to uridine
37
Where does RNA splicing occur?
In the nucleus
38
What is primary RNA?
RNA with both introns and exons
39
Which molecules are responsible for RNA splicing?
Proteins called spliceosome
40
What is snRNA?
Small nucleur RNA that is part of the splicing process
41
What is alternative splicing and what is it's function?
By splicing the same gene in different way different but closely related proteins can be made and it's a way to optimize the DNA and for a faster way of evelution
42
Describe a typical exon
About 100-300 nucleotides long and start with AG and ends with G and ends with AG
43
Describe a typical intron
About 100-50 000 nucleotides long and starts with GU and ends with ACU(17-37 nucleotides)AG
44
What are splicing sites in DNA and primary RNA?
GT in the DNA and GU in the primary RNA and AG
45
What happens with imporperly processed RNA?
It is degredaded by the nuclear exosome with the protein RNA exonucleases
46
What is the 3’ UTR (UnTranslated Region) and what does it do?
It acts as a zip code for the mRNA so it ends up in the right place of the cell. It also in many cases does so the translation starts in specific sites of the cell to shorten the travel for the finish proteins. This enabled the cell to regulate gene expression independently which is very important for the neuron cell which is highly polarized.
47
What is translation control?
A common way for the cell to regulate gene expression by inihibintng mRNA to be translated by translation repressors
48
How can cells control gene regulation in response to the enviormeant?
Temperature and infection for example will decrease protein synthesis by phosphorylation of an initiation factor
49
What is leaky scanning?
Starting of the next codon for translation rather then the first AUG one
50
What are open reading frames (ORFs) and what are it's function?
short DNA sequences that begin with a start codon andend with a stop codon. It serves a regelatory function and will decrease translation downstream.
51
What is the typical half life of mRNA?
30 minuts if mRNA is correctly transcripted. Certain proteins such as growth factors and transcription factors have even shorter half life in the cytosol.
52
How can gene regulation be altered trhough protein control?
Many proteins are regulated trhough covalent bindings to different molecules that will regulate their behvaiour and function
53
Give some examples of non coding RNA
micro RNA, ribosomal RNA, transfer RNA
54
What is the function of mRNA?
They bind to mRNA to produce gene silencing through either preventing translation or leading to degredation.
55
What does small nuclear RNA do?(sRNA)
Process pre mRNA, they aid in regulation of transcription factors and RNA polymerase II, maintain telomers
56
What are non coding RNAs longer then 200 nucleotides called and what are their function?
long non coding RNA (lncRNA) and they have several different functions such as gene inhibition and gene activation such as e inactivation of transcription regulators, affecting splicing patterns, blocking of translation and inactivation of mammalian X chromosomes
57
Which steps are there for gene regulation and where do they occur?
Transcriptional control and RNA processing control that occurs in the nucleus, RNA localization control, translation control, mRNA degredation control, protein activity control.
58
Describe briefly what transcriptional control is
It regulates which parts of the genes that are being transcribed and which are not through transcription regulators that recognize the identity, position and arrangmeant of cis regulatory sequences.
59
Describe briefly RNA processing control
The main way is trhough splicing where the snRNA and proteins called spliceosomes binds to one side of the intron and loops it to cut it. They recognice the splicing sites GU and AG.
60
Describe briefly RNA localization control
Improperly transcribed mRNA gets degreaded and the untranslated part of the mRNA acts as zip code so it will be transferred to the right place and the translation will start there. Depending on where the mRNA is transported different parts of the cell can have different gene expressions.
61
Describe briefly translation control
The most common function is to interfere with translation through translational repressors that binds to the 5' end but there are also micro RNA and molecules that recognize the 3' poly A tail that can inhibit translation
62
Describe briefly mRNA degredation control
By regulating the half life of the mRNA the gene expression can be altered. The most common halflife is 30 minutes but certain mRNA such as growth factors and transcription factors have epescially short half life.
63
Describe two mechanisms of mRNA degredation
Either through shortening of the 3' poly A tail or by removing the cap of the 5' end.
64
Briefly describe protein activity control
By covalent bindings to different molecules the function of the protien can be regulated
65
What are transcriptomes?
All the types of mRNA
66
What are proteomes?
All the types of proteins the DNA codes
67
Describe the process of x-inactivation
It starts at the inactivation center near the middle of the chromosome (XIS) an RNA called xist will spread over the entire chromosome and lead to gene silencing which leads to about 90% of the chromosome being inactive. Which x chromosome is inactivated is chosen randomly.

Genetics written exam (8 decks)

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