Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Y1 Fundamentals of Life Science > L12: Regulating Gene Expression > Flashcards

L12: Regulating Gene Expression Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

What is the first step in gene expression after DNA?

A

DNA is transcribed into messenger RNA (mRNA) through the process of transcription

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

What does the primary mRNA transcript contain?

A

The primary mRNA transcript contains both exons (coding regions) and introns (non-coding regions)

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

What is the role of splicing in gene expression?

A

Splicing removes introns and joins exons together to form a mature mRNA sequence that can be translated into protein

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

What modifications occur to mRNA after splicing?

A

The mRNA undergoes a 5’ cap addition (guanine cap) and a 3’ polyadenylation (Poly-A tail) before being exported to the ribosome for translation

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

How many genes are estimated to be expressed in humans?

A

Around 20,000 genes are expressed in the human genome

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

What is differential splicing?

A

Differential splicing refers to the process by which different combinations of exons are joined together, creating various mRNA variants and, therefore, different proteins

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

How do specialised cell types like muscle and nerve cells differ despite having the same genome?

A

Specialised cells express different subsets of genes, leading to the production of unique proteins that give rise to their specialised functions

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

What are housekeeping genes?

A

Housekeeping genes are essential for basic cell functions and are expressed in nearly all cells (e.g., those encoding histones, RNA polymerase, and glycolytic enzymes)

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

What is the role of specific proteins in specialised cells?

A

Specific proteins, such as myosin in muscle cells or microtubule-associated proteins in neurons, are responsible for the distinct functions of each cell type

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

How are gene expression levels regulated in cells?

A

Gene expression is regulated through mechanisms such as chromatin modifications, transcriptional control, splicing, translation, and protein degradation

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

What is the difference between constitutive and inducible gene expression?

A

Constitutive gene expression is always active, while inducible gene expression is activated under specific conditions or stimuli

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

What is the significance of microRNAs in gene regulation?

A

MicroRNAs help fine-tune gene expression by binding to mRNA and inhibiting its translation or promoting its degradation

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

What is transcriptional regulation?

A

Transcriptional regulation controls whether genes are transcribed into mRNA, influencing protein production

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

How does the stability of mRNA affect protein production?

A

The stability of mRNA determines how long it remains in the cell, impacting how much protein is produced from it. Less stable mRNA may degrade before translation, while more stable mRNA may produce more protein

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

What role does phosphorylation play in protein regulation?

A

Phosphorylation can activate or deactivate proteins, influencing their activity within the cell

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

What is an example of rapid protein regulation in response to environmental changes?

A

Hypoxia-inducible factor (HIF1) is a protein that is usually degraded but stabilises when oxygen levels are low, allowing it to activate responses to low oxygen conditions

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

What percentage of the human genome is involved in coding for proteins?

A

About 24% of the human genome is involved in coding for proteins, while the rest consists of non-coding regions, including introns

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

What is alternative splicing? How does it contribute to protein diversity?

A

Alternative splicing allows different combinations of exons to be joined together, leading to the production of multiple protein isoforms with distinct functions from a single gene

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

What is the role of RNA polymerase in gene expression?

A

RNA polymerase is an enzyme that synthesises RNA from a DNA template during the transcription process

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

How do transcription factors regulate gene expression?

A

Transcription factors are proteins that bind to specific DNA sequences near genes, either promoting or inhibiting the transcription of those genes

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

What is the function of histone proteins in gene regulation?

A

Histones help package DNA into chromatin and can be modified (e.g., acetylation or methylation) to regulate gene accessibility and expression

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

What is the significance of epigenetic modifications in gene expression?

A

Epigenetic modifications, such as DNA methylation and histone modification, can turn genes on or off without altering the DNA sequence itself, influencing gene expression

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

What is the difference between gene expression in prokaryotes and eukaryotes?

A

In prokaryotes, gene expression is simpler with transcription and translation occurring simultaneously, while in eukaryotes, transcription happens in the nucleus, and translation occurs in the cytoplasm after mRNA processing

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

What is RNA interference (RNAi)?

A

RNA interference is a process where small RNA molecules, such as microRNAs or small interfering RNAs (siRNAs), regulate gene expression by targeting mRNA for degradation or inhibiting translation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are polycistronic and monocistronic mRNA?

A

Polycistronic mRNA can encode multiple proteins from a single transcript (common in prokaryotes), while monocistronic mRNA encodes a single protein (typical in eukaryotes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How is gene expression regulated within a cell?

A

Gene expression can be active, repressed, or silenced. If a gene is not needed, it may be methylated and never expressed, or it can be dynamically regulated and activated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What percentage of genes do not have introns?

A

About 3% of genes do not have introns and are single exon genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the general size of exons and introns in most genes?

A

Exons are usually smaller, around 200 base pairs or less, while introns are much larger, ranging from 10 base pairs to over 100,000 base pairs

29
Q

How are exons and introns processed during transcription?

A

Exons are spliced together, and introns are removed in a highly regulated, co-transcriptional process involving RNA polymerase and splicing factors

30
Q

How can you experimentally determine if splicing has occurred in a gene?

A
  • By using PCR with primers designed for amplification of exon regions, you can identify splicing events by comparing the size of DNA and RNA fragments
  • A smaller band in the RNA sample indicates that splicing has occurred and introns have been removed
31
Q

How has gene sequencing improved the study of splicing?

A

With advanced techniques like rapid gene sequencing, you can now identify which splice variants are expressed in RNA populations within a cell

32
Q

What evolutionary advantage does the intron-exon structure of genes provide?

A

Introns allow for genetic rearrangement and exon shuffling, where exons (which code for important protein sites) can be rearranged and combined with other genes, facilitating the generation of nre protein functions and increasing genetic diversity

33
Q

Why is exon shuffling considered an important mechanism in evolution?

A

Exon shuffling enables recombination of exons from different gene, creating new protein combinations and functional domains, leading to novel protein functions and contributing to evolutionary diversity

34
Q

Can introns be included in protein products?

A

Yes, there are cases where intronic sequences can be retained in the protein product and can add new functional domains or regulatory elements to the protein, contributing to its functionality

35
Q

What is the role of splicing factors in gene regulation?

A

Splicing factors bind to the RNA during transcription and regulate the removal of introns and the joining of exons, a process that is essential for generating mature mRNA

36
Q

What is a co-transcriptional process in RNA processing?

A

Co-transcriptional processes occur during transcription, where RNA polymerase synthesises RNA and splicing factors simultaneously process the RNA, including capping and splicing

37
Q

What is the relationship between RNA polymerase and splicing factors?

A

RNA polymerase assembles on DNA to transcribe RNA, and splicing factors are associated with the carboxy terminus of RNA polymerase to facilitate RNA splicing during transcription

38
Q

How does the chromatin structure affect RNA splicing?

A

Chromatin structure, including epigenetic modifications like methylation, can influence the accessibility of splicing factors to the gene, thus affecting the splicing process

39
Q

Why do exons vary in size compared to introns?

A

Exons are usually smaller because they contain the coding sequences that will become part of the protein, while introns are non-coding regions that can be larger and may serve regulatory or structural roles

40
Q

What role does methylation play in gene expression regulation?

A

Methylation of DNA, particularly in the promoter region or around genes, typically represses gene expression by making the gene less accessible for transcription

41
Q

What is the significance of the carboxy terminus of RNA polymerase in transcription?

A

The carboxy terminus of RNA polymerase is where splicing factors are recruited to regulate the splicing process as RNA is synthesised

42
Q

What sequence signals the start of an intron on the 5’ end?

A

An AG followed by a GQ sequence on the 5’ end signals the start of an intron

43
Q

What sequence signals the end of an intron on the 3’ end?

A

A sequence on the 3’ end of an intron signals the end of the intron and the beginning of the next exon

44
Q

What is the “branch point” in RNA splicing?

A
  • The branch point is a sequence in the middle of the intron crucial for the initial splicing process - allows lariat formation, initiating the loop structure that allows intron excision
  • Typically an adenine
45
Q

What is the function of the 5’ donor site and 3’ acceptor site?

A

The 5’ donor site and 3’ acceptor site are where the intron is cut out, allowing exon ends to join

46
Q

What are snRNPs in RNA splicing?

A

snRNPs (small nuclear ribonucleoproteins) are complexes containing small nuclear RNAs essential for recognising exon-intron boundaries and aiding in splicing

47
Q

Which small nuclear RNAs are involved in RNA splicing?

A

Small nuclear RNAs like U1, U2, U4, U5, and U6 are involved in the splicing complex

48
Q

What is the spliceosome?

A

The spliceosome is a complex of proteins and snRNPs that facilitates the splicing of RNA by recognising and binding to exon-intron boundaries

49
Q

How do small nuclear RNAs (snRNAs) contribute to splicing specificity?

A

snRNAs pair with complementary sequences on the RNA, guiding the snRNPs to the correct intron-exon boundaries

50
Q

What are heterogeneous nuclear ribonucleoproteins (hnRNPs)?

A

hnRNPs are proteins that bind to exons, prevent unintended splicing by suppressing splicing or modulating exon inclusion to regulate mRNA diversity, stabilising exon-exon boundaries

51
Q

What role do serine-arginine-rich (SR) proteins play in splicing?

A

SR proteins promote splicing by binding to specific exon sequences, enhancing spliceosome assembly

52
Q

What is alternative RNA splicing?

A

Alternative RNA splicing is a process where different combinations of exons are joined, leading to diverse protein products from a single gene

53
Q

How does cellular context affect RNA splicing?

A

Cellular context, including factors like cell type and environment, can influence which exons are included or skipped in splicing

54
Q

What is the role of U1 and U2 snRNPs in splicing initiation?

A

U1 binds to the 5’ splice site, while U2 binds to the branch point sequence, marking the start of the splicing process

55
Q

How do lariat structures form in splicing?

A

A lariat loop forms when the intron’s branch point connects to the 5’ splice site, enabling the spliceosome to join exon ends

56
Q

How does the spliceosome facilitate exon joining?

A

The spliceosome brings the ends of the exons together, allowing them to connect and release the intron lariat

57
Q

What is the fate of introns after they are spliced out?

A

Introns are usually degraded after splicing

58
Q

What is exon skipping?

A

Exon skipping is when a particular exon is excluded from the final mRNA transcript due to regulatory proteins

59
Q

What effect does alternative splicing have on protein diversity?

A

Alternative splicing increases protein diversity by allowing different proteins to be produced from the same gene

60
Q

How does alternative splicing contribute to cellular specialisation?

A

Alternative splicing creates cell-specific proteins, enabling specialised functions in different cell types

61
Q

How does alternative splicing relate to disease?

A

Misregulation of splicing can lead to disease by creating faulty proteins, such as in certain cancers, spinal muscular atrophy, and cystic fibrosis

62
Q

What is an example of a protein affected by alternative splicing?

A

Vascular endothelial growth factor (VEGF) has multiple splice variants that influence cell association and diffusion properties

63
Q

How does alternative start site selection affect gene expression?

A

Different start sites can lead to different exon combinations, influencing which protein variants are produced in each cell type

64
Q

What can happen if a splice site is skipped, mutated, or retained inappropriately?

A

A mutation, skipping or retaining splice sites incorrectly can lead to exon skipping, intron retention or production of a truncated or non-functional proteins, impacting cell function

65
Q

What role do splice silencers play in RNA splicing?

A

Splice silencers are RNA sequences that bind regulatory proteins to inhibit splicing at specific sites, modulating which exons are included

66
Q

How do splice enhancers influence the splicing process?

A

Splice enhancers are sequences within RNA that recruit proteins to promote splicing at nearby exon-intron junctions

67
Q

Why is U6 snRNA considered essential in splicing?

A

U6 snRNA helps catalyse the splicing reaction by forming the active site within the spliceosome for exon ligation

68
Q

How does the spliceosome ensure accuracy during splicing?

A

The spliceosome assembles stepwise, allowing multiple checkpoints for ensuring correct recognition and pairing of exon-intron boundaries

69
Q

What effect does alternative 3’ or 5’ splice site selection have on the mRNA product? What is the effect on the immune system?

A
  • Alternative 3’ or 5’ splice site selection can alter exon length, leading to proteins with altered or truncated domains
  • In immune cells can produce different antibody forms or cytokine variants, crucial for immune response diversity

Y1 Fundamentals of Life Science (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions