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Ap Bio > Chapter 18 > Flashcards

Chapter 18 Flashcards

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1
Q

What is differential gene expression?

A

The expression of different genes by cells with the same genome.

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2
Q

Why do prokaryotes and eukaryotes regulate gene expression?

A

In response to environmental conditions.

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3
Q

What is the operon model in bacteria?

A

A mechanism for control of gene expression involving a cluster of functionally related genes.

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4
Q

What is an operator in gene regulation?

A

A segment of DNA that acts as a switch to control gene expression.

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5
Q

What is an operon?

A

The entire stretch of DNA that includes the operator, the promoter, and the genes they control.

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6
Q

What is the role of a repressor in gene regulation?

A

It prevents gene transcription by binding to the operator and blocking RNA polymerase.

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7
Q

What is a corepressor?

A

A molecule that cooperates with a repressor protein to switch an operon off.

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8
Q

What happens to the trp operon when tryptophan is present?

A

The repressor is activated, turning the operon off.

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9
Q

What type of operon is the trp operon?

A

A repressible operon.

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10
Q

What is an inducible operon?

A

An operon that is usually off and is turned on by an inducer that inactivates the repressor.

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11
Q

What is the lac operon responsible for?

A

It contains genes that code for enzymes used in the hydrolysis and metabolism of lactose.

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12
Q

What is the function of catabolite activator protein (CAP)?

A

It acts as an activator of transcription when glucose is scarce.

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13
Q

What is the role of cyclic AMP (cAMP) in gene regulation?

A

It activates CAP, which enhances transcription of operons like the lac operon.

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14
Q

True or False: All cells in an organism are genetically identical.

A

True.

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15
Q

What is differential gene expression responsible for?

A

Differences between cell types in multicellular organisms.

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16
Q

What is epigenetic inheritance?

A

The inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence.

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17
Q

What is histone acetylation?

A

The addition of acetyl groups to histones, promoting loose chromatin structure for transcription.

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18
Q

What is DNA methylation associated with?

A

Reduced transcription in some species.

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19
Q

What are control elements?

A

Segments of noncoding DNA that serve as binding sites for transcription factors.

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20
Q

Fill in the blank: A _______ is a molecule that inactivates the repressor in an inducible operon.

A

inducer

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21
Q

What is the significance of chromatin structure in gene expression?

A

It regulates gene expression by influencing the accessibility of DNA for transcription.

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22
Q

What are the two types of negative gene regulation?

A
  • Repressible operons * Inducible operons
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23
Q

What happens to transcription when glucose levels increase?

A

CAP detaches from the lac operon, and transcription returns to a normal rate.

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24
Q

What does abnormal gene expression lead to?

A

Diseases, including cancer.

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25
What is the primary role of transcription factors?
To initiate transcription by binding to control elements.
26
What is a primary RNA transcript also known as?
pre-mRNA
27
Define intron in the context of RNA.
Non-coding segments of RNA that are removed during RNA processing
28
Define exon in the context of RNA.
Coding segments of RNA that are retained after RNA processing
29
What does the poly-A signal indicate in RNA processing?
It signals the addition of a poly-A tail at the 3′ end
30
What is the role of transcription factors in transcription?
They assist eukaryotic RNA polymerase in initiating transcription
31
True or False: General transcription factors are essential for the transcription of all protein-coding genes.
True
32
What are proximal control elements?
Control elements located close to the promoter
33
What are distal control elements also known as?
Enhancers
34
What is the function of an activator in gene transcription?
It binds to an enhancer and stimulates transcription of a gene
35
Fill in the blank: Activators have two domains: one that binds _______ and a second that activates transcription.
DNA
36
What is combinatorial control of gene activation?
Activation of transcription only occurs with a specific combination of control elements and activator proteins
37
Define co-expressed eukaryotic genes.
Genes that are not organized in operons but have the same combination of control elements
38
What is the significance of nuclear architecture in gene expression?
Loops of chromatin may congregate at specific sites for transcriptional regulation
39
What is alternative RNA splicing?
The process that produces different mRNA molecules from the same primary transcript
40
What can block the initiation of translation of selected mRNAs?
Regulatory proteins binding to sequences or structures of the mRNA
41
True or False: Eukaryotic mRNA has a shorter lifespan than prokaryotic mRNA.
False
42
What is the role of ubiquitin in protein degradation?
It marks proteins for degradation by proteasomes
43
What does RNA interference (RNAi) involve?
The blocking of gene expression by small interfering RNAs (siRNAs)
44
What role do microRNAs (miRNAs) play in gene regulation?
They can bind to mRNA, leading to degradation or blocking of translation
45
What is the process of determination in cellular differentiation?
It irreversibly commits a cell to its final fate
46
Define morphogenesis.
The physical processes that give an organism its shape
47
What are cytoplasmic determinants?
Maternal substances in the egg that influence early development
48
What is induction in embryonic development?
The process where signal molecules from embryonic cells cause transcriptional changes in nearby target cells
49
What is MyoD?
A master regulatory gene that encodes a transcription factor committing cells to become skeletal muscle
50
What is pattern formation in developmental biology?
The development of a spatial organization of tissues and organs
51
What is positional information?
Molecular cues that control pattern formation and tell a cell its location relative to body axes
52
What organism is commonly studied for pattern formation?
Drosophila melanogaster
53
What is the size of a mature, unfertilized egg?
0.5 mm
54
What is the term for the early stage of development from egg to larva?
Development from egg to larva
55
What is the embryonic structure characterized by body segments?
Segmented embryo
56
What is the role of nurse cells in embryonic development?
Provide nutrients and support to developing eggs
57
What are maternal effect genes also known as?
Egg-polarity genes
58
What is the function of the bicoid gene?
Affects the front half of the body
59
What happens to an embryo if the mother has no functional bicoid gene?
Lacks the front half of its body and has duplicate posterior structures
60
What hypothesis explains how gradients of substances establish an embryo’s axes?
Morphogen gradient hypothesis
61
What are oncogenes?
Cancer-causing genes in some types of viruses
62
What can convert a proto-oncogene into an oncogene?
Movement of DNA, amplification of the proto-oncogene, point mutations
63
What do tumor-suppressor genes normally do?
Help prevent uncontrolled cell growth
64
What is a common mutation in the ras proto-oncogene associated with?
Increased cell division
65
What is the role of the p53 tumor-suppressor gene?
Prevents a cell from passing on mutations due to DNA damage
66
True or False: Multiple mutations are generally needed for full-fledged cancer.
True
67
What are the four major types of breast cancer identified through genomics?
* Luminal A * Luminal B * HER2 * Basal-like
68
What are inherited mutations in the BRCA1 or BRCA2 gene commonly associated with?
Inherited breast cancers
69
What is the relationship between environmental factors and cancer?
Environmental influences can cause mutations leading to cancer
70
What can viruses do to contribute to cancer?
Interfere with normal gene regulation
71
Fill in the blank: The product of the mother’s bicoid gene is essential for setting up the ______ end of the embryo.
anterior
72
Fill in the blank: Mutations that decrease protein products of ______ genes may contribute to cancer onset.
tumor-suppressor
73
What is the significance of the fly with legs emerging from its head?
Result of a single mutation in one gene
74
What are embryonic lethals?
Mutations causing death during embryogenesis
75
What is a common characteristic of a cancerous cell at the DNA level?
At least one active oncogene and mutations in several tumor-suppressor genes
76
What is the effect of point mutations in proto-oncogenes?
Increase in gene expression
77
What can DNA sequencing detect?
Mutations ## Footnote Mutations can be linked to various genetic disorders and cancers.
78
What role do viruses play in cancer?
They can cause cancer in humans and animals by interfering with normal gene regulation.
79
How do viruses interfere with gene regulation?
By integrating into the DNA of a cell.
80
What is a powerful biological agent related to cancer?
Viruses.
81
What are the steps involved in gene expression regulation?
* Chromatin modification * Transcription * RNA processing * mRNA degradation * Translation * Protein processing and degradation
82
What is the function of enhancers in gene regulation?
They bind specific transcription factors to regulate transcription initiation.
83
What determines the lifespan of mRNA?
Sequences in the 5′ and 3′ UTRs.
84
What is histone acetylation's effect on chromatin?
It loosens chromatin structure, enhancing transcription.
85
What effect does DNA methylation have on transcription?
It generally reduces transcription.
86
What are the types of operons mentioned?
* Repressible operon * Inducible operon
87
In a repressible operon, what happens when a corepressor is present?
The active repressor binds, and genes are not expressed.
88
In an inducible operon, what is the role of the inducer?
It binds to the inactive repressor, allowing gene expression.
89
What can small and/or large noncoding RNAs promote?
Heterochromatin formation, which can block transcription.
90
What is the role of miRNA or siRNA in mRNA regulation?
* Block translation of specific mRNAs * Target specific mRNAs for destruction
91
What is the consequence of protein overexpression in cell cycle regulation?
Cell cycle overstimulation and increased cell division.
92
What happens if a protein is absent in cell cycle regulation?
The cell cycle is not inhibited.
93
What are the components of an operon?
* Promoter * Genes * Operator * RNA polymerase
94
What is the relationship between transcription factors and enhancers?
Transcription factors bind to DNA control elements in enhancers to initiate transcription.
95
What is alternative RNA splicing?
The process by which a primary RNA transcript can be spliced into different mRNA variants.
96
What is the role of transcription initiation factors?
They control the initiation of translation.
97
What is Cell Degradation?
The digestion of an old cell.

Ap Bio (4 decks)

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