Human Genetics > Topic 8 - Gene Expression > Flashcards

Topic 8 - Gene Expression Flashcards

(94 cards)

Study These Flashcards
1
Q

What determines if a gene is expressed?

A

DNA accessibility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Difference between euchromatin and heterochromatin?

A

Euchromatin is loose and active heterochromatin is tight and inactive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why does heterochromatin prevent transcription?

A

DNA is inaccessible to transcription machinery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is chromatin remodeling?

A

Unwinding chromatin to allow transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the main role of histones?

A

Packaging DNA into chromatin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why do histones bind DNA?

A

Positive charge interacts with negatively charged DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Which amino acid is key in histone modification?

A

Lysine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does histone acetylation do?

A

Loosens chromatin and increases transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What enzyme adds acetyl groups?

A

HAT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What enzyme removes acetyl groups?

A

HDAC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the effect of histone methylation?

A

Usually condenses chromatin and reduces transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the effect of histone phosphorylation?

A

Loosens chromatin and increases transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which modifications activate transcription?

A

Acetylation, phosphorylation & demethlyation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which modifications repress transcription?

A

Methylation and deacetylation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is DNA methylation?

A

Addition of methyl group to cytosine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the effect of DNA methylation?

A

Condenses DNA & Decreases transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Where does DNA methylation occur?

A

CpG sites

*Cytosine linked to Guanine by phosphate on the same strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are CpG islands?

A

Clusters of CpG sites near promoters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens when CpG islands are methylated?

A

Gene is silenced, since DNA is condensed and transcription decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What happens when CpG islands are unmethylated?

A

Gene can be expressed, since DNA is no longer condensed and accessible for transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is epigenetics?

A

Heritable gene expression changes without DNA sequence change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why is DNA methylation important?

A

Long term gene silencing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is transcription?

A

Copying DNA into RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What enzyme performs transcription?

A

RNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What are the three stages of transcription?
Initiation elongation termination
26
What is produced during transcription?
mRNA
27
Is mRNA immediately functional?
No it must be processed
28
What is the promoter?
DNA region where transcription begins
29
What is the TATA box?
Promoter sequence recognized by transcription factors
30
What binds first at the promoter?
Transcription factors
31
What do transcription factors do?
Recruit RNA polymerase
32
What is the transcription initiation complex?
RNA polymerase plus transcription factors assembled at promoter
33
What direction is RNA synthesized?
5 to 3
34
Which DNA strand is used?
Template strand
35
What are exons?
Coding regions
36
What are introns?
Non coding regions removed later
37
What are enhancers?
Distal control elements that increase transcription | *Distal control elements are segments of non-coding DNA that inc/dec trp
38
What are proximal control elements?
Regulatory sequences near promoter
39
What do activators do?
Increase transcription
40
What do repressors do?
Decrease transcription
41
Where are control elements located?
Upstream of gene
42
When is transcription mainly regulated?
Initiation stage
43
What are transcription factors?
Proteins that regulate gene expression
44
Can one transcription factor regulate multiple genes?
Yes
45
How can transcription factors be inhibited?
Inhibitor blocks DNA binding
46
What happens if transcription factors cannot bind?
No transcription occurs
47
How do hormones like estrogen affect transcription?
Removes DNA inhibitor and binds TF to DNA to activate gene expression (increase transcription)
48
What happens during elongation?
RNA polymerase adds nucleotides
49
What happens during termination?
RNA polymerase releases RNA transcript
50
What signals termination in eukaryotes?
Polyadenylation signal | *AAUAAA sequence in RNA located near 3' end
51
What happens after polyA signal?
Polymerase detaches shortly after
52
How do prokaryotes terminate transcription?
Terminator sequence
53
What is post transcriptional processing?
Modification of RNA before translation
54
What is the 5 prime cap?
An inverted GTP added to 5' end that protects RNA and aids export in cytoplasm
55
What is the polyA tail?
Long stretch of A's added after transcription which stabilizes RNA and aids export
56
What is splicing?
Removal of introns | *Only in Eukaryotes
57
What is alternative splicing? | *onlt in eukaryotes
One mRNA in a eukaryotic cell is spliced in different ways to create multiple variants. One gene produces multiple proteins
58
What is RNA editing? (specifically after transcription)
Changing RNA sequence after transcription
59
What is RNA localization?
Transporting RNA to specific regions
60
What is RNA degradation?
Breakdown of RNA
61
What is translation?
Making protein from mRNA
62
What regulates translation?
mRNA availability and regulatory proteins
63
What are post translational modifications?
Changes to protein after synthesis
64
Give examples of post translational modifications
Cleavage (cutting protein at specifc sites), phosphorylation (adding phosphate group to protein) & glycosylation (adding sugar chains to protein)
65
What is protein degradation?
Breaking down proteins
66
Why is gene regulation important?
Allows for cell specialization and environmental response (cells being able to adapt) so genes can be expressed or not
67
What is the key regulatory step in gene expression?
Transcription initiation
68
What happens if chromatin is tightly packed?
Gene is not expressed
69
What happens if chromatin is loosely packed?
Gene is expressed
70
What modification reduces DNA histone attraction?
Acetylation
71
What modification strengthens DNA histone attraction?
Methylation
72
What type of regulation is DNA methylation?
Epigenetic
73
What happens to gene expression when histones are deacetylated?
Decreases
74
What happens when histones are acetylated?
Increases transcription
75
What is the relationship between CpG methylation and promoters?
Methylation near promoter silences gene
76
What is required for RNA polymerase binding?
Transcription factors
77
What is the function of enhancers?
Increase transcription rate
78
What is the function of repressors?
Block transcription
79
What happens to RNA before leaving nucleus?
It is capped polyadenylated and spliced
80
What is the final product of gene expression?
Functional protein
81
What is cytidine deaminase
C base to U base
82
T or F: Do mRNAs travel freely through the nuclear pore
False
83
What are 2 examples of mRNA Decay during translation?
5' end decapping enzymes to allow for exonucleases to degrade mRNA 3' end Deadenylase which removes the polyA tail to reveal a free 3' end for exonucleases to degrade mRNA
84
How do miRNA and siRNA cause mRNA decay?
miRNA and siRNA guide the RISC complex to complementary mRNA, leading to mRNA degradation—siRNA usually causes direct cleavage, while miRNA promotes degradation and/or translation repression. (inhibition of translation)
85
What is the RISC complex?
The RISC (RNA-induced silencing complex) is a protein complex that uses miRNA or siRNA as a guide to bind complementary mRNA and silence gene expression by cleaving the mRNA or inhibiting its translation.
86
What are UTRs?
UTRs (untranslated regions) are sequences at the 5′ and 3′ ends of mRNA that are not translated into protein but regulate mRNA stability, localization, and translation efficiency.
87
What happens during initiation of translation?
The small ribosomal subunit binds the mRNA, the initiator tRNA pairs with the start codon (AUG), and then the large ribosomal subunit joins to form a complete ribosome ready for protein synthesis.
88
What happens during elongation of translation?
The ribosome moves along the mRNA, tRNAs bring amino acids matching each codon, and peptide bonds form to extend the growing polypeptide chain.
89
What happens during termination of translation?
When a stop codon is reached, a release factor binds, the completed polypeptide is released, and the ribosome dissociates from the mRNA.
90
What are the two places where ribosomes exist?
Cytosol & Rough ER
91
Proteins made in the cytosol go where?
Cytosol,nucleus,mitochondria,chloroplast or peroxisome
92
Proteins made in the ER go where?
the Golgi,lysosome,vesicles,membrane or exocystosis
93
How are proteins targeted and degraded in the cell?
Proteins are tagged with ubiquitin on specific lysines (post-translational modification), then directed to the proteasome where they are hydrolyzed into peptides; removing ubiquitin can prevent degradation.
94
What is the Proteasome
The proteasome is a large protein complex that recognizes ubiquitin-tagged proteins and degrades them into small peptides through hydrolysis.
Human Genetics
flashcards
Decks in class (21)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions