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BS 181H > Exam 4 > Flashcards

Exam 4 Flashcards

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1
Q

Housekeeping genes

A

Genes that are needed by all cells all the time

Constitutively expressed

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2
Q

What is similar and what differs in cells and how does this lead to different protein production?

A

The DNA in each cell is the same, activators and repressors differ

Different RNA are made leading to the creation of different proteins

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3
Q

What controls cell identity?

A

The profile of transcription factors

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4
Q

What allows the selective production of RNA and how

A

Histones - DNA coils around histones and that

Transcription factors - bind to specific DNA sequences in promoter or enhancer regions, influencing the binding of RNA polymerase and other factors involved in transcription

RNA alternative splicing - by including or excluding specific exons

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5
Q

What controls protein production and activity and how

A

mRNA stability - influences how long an mRNA molecule remains available for translation

Translation - regulates the initiation, elongation, and termination of protein synthesis

Post-transitional modifications of proteins - alter their stability, activity, and localization by acting like an on/off switch for protein activity

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6
Q

What are the three DNA regions that regulate transcription?

A

Promoters
Enhancers
Silencers

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7
Q

Promoter

A

General transcription factors and RNA polymerase bind to the promoter to start transcription

Always at the beginning of a gene, and their orientation controls transcriptions direction

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8
Q

Enhancers

A

Bind to transcriptional activator proteins to increase transcription

Can be near or far from the transcription start site

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9
Q

Silencers

A

Bind to transcriptional repressor proteins that decrease transcription

Can be near or far from the transcription start site

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10
Q

Transcription factor

A

A protein that modulates transcription

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11
Q

Specific transcription factors

A

Activators and repressors that vary depending on the gene

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12
Q

General transcription factors

A

Transcription factors that bind all genes

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13
Q

How is transcription activated?

A

Activators bind to enhancers, general transcription factors bind the promoter

DNA loops to form a full complex

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14
Q

Transcriptional regulation

A

Regulatory transcription factors bind enhancers

This recruits general transcription factors to the promoter of the gene

General transcription factors recruit RNA polymerase, and transcription takes place

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15
Q

When does high/low/no gene expression occur

A

High: When both activators are present and repressors are absent

Low: one activator is present and repressor is absent

No transcription: both or one activator(s) are/is present and repressor is present

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16
Q

Gal4 and UAS

A

Gal4 is a transcription factor that binds galactose and upstream activating sequences (UAS) in DNA to turn on transcription

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17
Q

Heterochromatin

A

Condensed chromatin packed with histones

transcription is low

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18
Q

Euchromatin

A

Decondensed chromatin lightly packed with histones

transcription occurs

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19
Q

Histone acetylase (HAT)

A

adds acetyl groups to lysine in histones; this decreases histone binding and turns on gene expression

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20
Q

Histone deacetylase (HDAC)

A

removes acetyl groups; this increases histone binding and decreases gene expression

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21
Q

Histones are ___ rich; what happens to histone tails and how does this affect chromatin

A

Histones are lysine rich

The lysine in histone tails can be methylated or acetylated

acetyl groups remove the plus charge so the ionic interaction that binds DNA and histones disappears

Methyl groups do not change the overall charge, but it changes the base properties and how it interacts with other proteins, leading to histone binding

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22
Q

Epigenetic Effects

A

Don’t change the DNA sequence

Change the gene expression in an inheritable manner

Often associated with DNA methylation

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23
Q

Methylation

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A

Blocks transcription factors from binding which blocks gene expression

Targets Cytosines next to Guanines (CG islands)

Inheritable; when DNA replication occurs, enzymes methylate the new DNA daughter strand with a pattern like that of the parent strand

24
Q

Random X-inactivation

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A

Occurs at about the time of implantation in the uterine wall

In each cell lineage, the inactivated X remains inactivated

Calico cats are a result of a chromosome inactivation in a heterozygous female

25
How does X-inactivation occur?
The Xist gene makes a 'noncoding' RNA that binds the X-chromosome inactivation center (XIC) The X chromosome becomes coated with Xist RNA, which prevents transcription as Xist triggers DNA methylation
26
The two types of insulin receptors
IR-A: Binds to both insulin and insulin like growth factors - Exon 11 missing IR-B: Binds to just insulin - Exon 11 present
27
What regulates most gene activity in eukaryotic cells?
Alternative splicing
28
Alternative splicing
Splicing out an intron removes the RNA between the donor (d) and acceptor (a) sites at the intron ends All introns must be removed, but all pairings of d and a are allowed
29
Mechanisms of gene regulation in Eukaryotes
Chromatin modification DNA methylation Transcription RNA processing - alternative splicing srRNAs Translation Post-translational modification - phosphorylation, methylation, and acetylation
30
Transcription and translation in prokaryotes
Is coupled, meaning they occur at the same time
31
Gene regulation in Prokaryotes
Ribosomes bind all Shine-Dalgarno sequences and scan for the 1st AUG Proteins are then made independantly
32
Shine-Dalgarno
5' - AGGAGGU - 3'
33
What does each gene contain in prokaryotic cells?
A Shine-Dalgarno sequnece An AUG codon which determines reading frame A stop codon that ends translation
34
Operons
A functioning unit of DNA containing a cluster of genes and their regulatory regioins
35
Operator
Controls RNA polymerase
36
When should cells make enzymes to breakdown lactose?
Not when there is no lactose or glucose Not when there is glucose and no lactose Not when there is glucose and lactose YES when there is lactose and no glucose
37
How to increase gene expression
Turn on an activator or turn off a repressor
38
Positive transcriptional regulation
Activator binding induces transcription No activator = no transcription
39
Negative transcriptional regulation
The native state of DNA allows RNA polymerase to bind Repressor binding blocks transcription
40
The lac operon
Ensures the proper proteins to break down different types of sugars are only expressed when needed
41
lacY
makes the protein galactoside permease which functions as a transporter
42
lacZ
makes the protein b-Galactosidase which is functions as an enzyme
43
lacI
Makes a repressor protein which controls transcription Binds the operator and blocks RNA polymerase from transcribing proteins
44
Why is there no expression of the Lac operon if lactose is not present?
When lactose is present, so is allolactose which blocks the repressor
45
What effect does low glucose have on the Lac operon
Low glucose turns on the Lac activator (CRP-cAMP) by increasing cAMP
46
Allolactose
Binds to the lac operon repressor and prevents it from binding the promoter, which inhibits transcription
47
How do high glucose levels lower cAMP levels?
Glucose inhibits adenylate cyclase which blocks the conversion of ATP to cAMP
48
Catabolic Activator Protein (CAP)
a transcription factor that activates RNA polymerase when cAMP is high
49
How do cells w/ identical DNA specialize?
Different cells express unique transcription factors, thus they make different types of mRNAs
50
Genotype
the information stored in DNA: types of genes, gene alleles, and level of gene expression
51
allele
a specific version of a gene
52
phenotype
in any measurable trait: eye color, height, blood type, cell growth, cell shape, or the type of sugar found on the surface of red blood cell
53
Sickle cell anemia (SCA)
Caused by one missense mutation that switches GLU to VAL differences in 'genotypes' of the hemoglobin gene give rise to the phenotype the phenotype arises due to changes in the structure of the hemoglobin protein
54
What charge do basic and acidic amino acids have?
basic AAs have a plus charge acidic AAs have a negative charge
55
What causes the rod formation of hemoglobin in sickle cells?
Converting acidic AAs to hydrophobic AAs cause the rod shape

BS 181H (4 decks)

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