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Biology 1113 > Chapter 18 > Flashcards

Chapter 18 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What regulates development in multicellular euk?

A

gene expression

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2
Q

What regulates development in bacteria?

A

They regulate transcription to respond to environmental changes.

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3
Q

What type of bacteria is favored by natural selection?

A

The kind that produces only what is needed by the cell.

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4
Q

How can a cell regulate the production of enzymes?

A

feedback inhibition
or
gene regulation

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5
Q

operon model

A

a cluster of functionally related genes can be coordinately controlled by a single “switch”

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6
Q

operon

A

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

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7
Q

Trp operon

A

5 genes clustered together with a single promoter

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8
Q

operator

A

the “on-off switch” -> a segment of DNA usually in the promoter

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9
Q

repressor

A

can switch the operon off

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10
Q

regulatory gene

A

produces the repressor / produced by separate gene from the DNA it is regulating

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11
Q

By itself, is trp repressor active or inactive?

A

inactive

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12
Q

corepressor

A

a molecule that cooperates with a repressor

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13
Q

How does the repressor prevent gene transcription?

A

binds to the operator and blocks RNA polymerase

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14
Q

repressible operon

A

(like Trp operon) an operon that is usually on

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15
Q

inducible operon

A

(like the lac operon) an operon that is usually off -> needs inducer to inactivate repressor and turn on transcription

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16
Q

inducer

A

inactivated repressor and turns on transcription

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17
Q

When are hydrolyzing enzymes needed?

A

When lactose is present

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18
Q

What does the lac operon do?

A

It codes for enzymes used in hydrolysis and metabolism of lactose

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19
Q

negative control

A

operons are switched off by the active form of the repressor

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20
Q

positive control

A

stimulatory protein activator of transcription

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21
Q

CAP

A

catabolite activator protein

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22
Q

What can activate CAP? (When glucose is short.)

A

cyclic AMP (cAMP)

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23
Q

How does the activated CAP accelerate transcription?

A

through attaching to the promoter and increasing the affinity of RNA polymerase

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24
Q

At what stages is gene expression regulated?

A
  1. Transcription (chromatin, transcription factors)
  2. mRNA processing (splicing, tail,cap)
  3. mRNA transport
  4. mRNA stability/degradation
  5. Initiation of Translation
  6. Control of protein activity (posttranslational modifications)
  7. protein degradation
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25
Q

What do chemical modifications do to histones and DNA of chromatin?

A

influence chromatin structure and gene expression

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26
Q

The addition of _____ can condense chromatin.

A

methyl groups

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27
Q

histone acetylation

A

acetyl groups are attached to positively charged lysines in histone tails

loosens chromatin structure to promote transcription

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28
Q

DNA methylation

A

the addition of methyl groups to certain bases in DNA (usually cytosine)

reduces transcription in some species (prevent (or enhance) some binding of transcription factors, long-term inactivation, regulates one of the parents in genomic imprinting)

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29
Q

Do these changes change DNA?

A

No

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30
Q

Can these modifications be passed to the next generation?

A

Yes

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31
Q

epigenetic inheritance

A

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

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32
Q

Epigenetic inheritance in twins

A

more epigenetic tags as they get older

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33
Q

How do chromatin-modifying enzymes provide initial control of gene expression?

A

by making a region of DNA either more or less able to bind the transcription machinery

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34
Q

What is involved in regulation of transcription initiation?

A

proteins that bind to DNA

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35
Q

control elements

A

segments of noncoding DNA that serve as binding sites for transcription factors (critical to precise regulation of gene expression)

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36
Q

Where are proximal control elements located?

A

close to the promoter

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37
Q

enhancers (distal control elements)

A

may be far away from a gene or located in an intron

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38
Q

general transcription factors

A

can bind to the TATA box or other transcription factors and RNA polymerase II

essential for coding of all protein-coding genes

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39
Q

specific transcription factors

A

some control elements must interact with in euk for high levels of transcription

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40
Q

activator (specific transcription factor)

A

a protein that binds to an enhancer and stimulated transcription of a gene

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41
Q

What are an activators 2 domains?

A

one that binds to DNA and the other activates transcription

42
Q

What do bound activators do?

A

They facilitate a sequence of protein-protein interactions that result in transcription of a given gene.

43
Q

Can some transcription factors act as repressors?

A

Yes, they inhibit expression of a particular gene by a variety of methods

44
Q

When can a particular combination of control elements activate transcription?

A

Only when the appropriate activator proteins are present

liver and lens can make albumin and crystallin but only lens makes crytallin and only liver makes albumin

45
Q

alternative RNA splicing

A

different mRNA molecules are produced from the same primary transcript (depending on introns and exons)

46
Q

How can the initiation of translation of selected mRNA be blocked by regulatory proteins?

A

The proteins bind to sequences or structures of the mRNA and prevent the attachment of ribosomes

47
Q

Where do the nucleotide sequences that influence the lifespan of mRNA in euk reside?

A

The untranslated region (UTR) at the 3’ end of the molecule

48
Q

What regulated the length of time each protein functions?

A

selective degredation

49
Q

ubiquitin

A

how cells mark proteins for degredation

50
Q

proteasomes

A

recognize ubiquitin and degrade the protein

51
Q

How much of DNA is transcribed into noncoding RNAs?

A

most of it

52
Q

2 points where noncoding RNAs regulate gene expression

A

mRNA translation

chromatin configuration

53
Q

MicroRNAs (miRNAs)

A

small single-stranded RNA molecules that can bind to mRNA

54
Q

What do miRNAs do?

A

They can degrade mRNA or block its translation

55
Q

How can a single miRNA potentially regulate the expression of many different genes?

A

imperfect base pairing

56
Q

differential gene expression

A

the expression of different genes by cells with the same genome

57
Q

When does a fertilized egg give rise to many different types of cells?

A

During embryonic development

58
Q

3 factors in transformation from zygote to adult

A

cell division
cell differentiation
morphogenesis

59
Q

What if only cell division happened?

A

Identical cells

60
Q

cell differentiation

A

the process by which cells become specialized in structure and function

61
Q

morphogenesis

A

the physical processes that give an organism its shape

62
Q

What 2 major sources of developmental information “tell” a cell which genes to express?

A

The egg’s cytoplasm (cytoplasmic determinants)
and
the environment around a particular cell [esp from nearby embryonic cells] (inductive signals)

63
Q

What is contained in an egg’s cytoplasm?

A

RNA, proteins, and other unevenly distributed substances

64
Q

cytoplasmic determinants

A

maternal substances in the egg that influence early development

65
Q

How does the egg lead to different gene expression?

A

As the zygote divides by MITOSIS, cells contain different cytoplasmic determinants

66
Q

induction

A

signal molecules from embryonic cells cause transcriptional changes in nearby target cells

67
Q

determination

A

commits a cell to its final fate

precedes differentiation

68
Q

Differentiated cells are specialists at …

A

making tissue-specific proteins

- specific structure and function

69
Q

MyoD

A

(not active in the embryonic precursor cell) one of several “master regulatory genes” that produce proteins that commit the cell to becoming skeletal muscle

70
Q

master regulatory genes

A

commit the cell to becoming skeletal muscle

71
Q

muscle cells develop from …

A

… embryonic precursor cells that have a potential to develop into number of cells

72
Q

What leads to the activation of a master regulatory gene?

A

signals from other cells

73
Q

myoblast

A

when a cell is irreversibly committed (to being a skeletal muscle cell?)

74
Q

body plan

A

overall arrangement

75
Q

When is the body plan established?

A

during differentiation

76
Q

pattern formation

A

development of a spatial organization of tissues and organs (cytoplasmic determinants and inductive signals both contribute)

77
Q

When does pattern formation begin in animals?

A

With the establishment of the major axes

78
Q

Positional information

A

the molecular cues that control pattern formation, tells a cell its location relative to the body axes and to neighboring cells

79
Q

homeotic genes

A

control pattern formation in late embryo, larva, and adult stages

80
Q

embryonic lethals

A

mutated genes that kill the embryo

81
Q

number of genes necessary for normal segmentation in a fly

A

120

82
Q

maternal effect genes

A

encode cytoplasmic determinants
create mutant offspring regardless of genotype
supplied by nurse cells

83
Q

egg-polarity genes

A

another name for maternal effect genes

84
Q

bicoid gene

A

a maternal effect gene that affects the fly’s front half

(no bicoid = two posteriors) [morphogen]

85
Q

morphogen

A

morphogens establish an embryo’s axes and other features of its form

86
Q

3 reasons bicoid research was groundbreaking

A

identified a specific protein required for some early steps in pattern formation

increased understanding of the mother’s role in embryo development

demonstrated a key developmental concept that a gradient of molecules can determine polarity and position in the embryo

87
Q

Mutations to what can cause cancer?

A

genes that regulate cell growth and division, including growth factors, their receptors and intracellular molecules of signaling pathways

88
Q

What can cause cancer mutations?

A

Spontaneous or environment (Radiation, chemicals, and some viruses)

89
Q

Oncogenes

A

cancer-causing genes in some types of viruses

[close counterparts in humans and animals]

90
Q

Proto- oncogenes

A

the corresponding normal cellular genes responsible for normal growth and division

91
Q

Proto-oncogenes can be converted to oncogenes by

A

Movement of DNA within the genome (near active promote = increased transcription)

amplification of a proto-oncogene (increase # copies)

point mutations in the proto-oncogene or its control elements (increase gene expression)

92
Q

tumor-suppresor genes

A

normally help prevent uncontrolled cell growth

93
Q

What happens if the protein production of tumor-suppressor genes is decreased?

A

Cancer may onset

94
Q

What do tumor-suppressor genes do?

A

Repair damaged DNA

control cell adhesion

act in cell-signaling pathways that inhibit the cell cycle

95
Q

ras gene (proto-onco)

A

mutations in ras can lead to hyperactivity and increased division

G protein - relay from growth factor to protein kinases -> stimulate cell cycle

mutation triggered without growth factor

96
Q

p53

A

prevents a cell from passing on mutations due to DNA damage

synthesizes protein to stop cell-cycle

mutation = no stop

97
Q

Can only one mutation lead to cancer?

A

Typically need mutliple

98
Q

DNA level of cancer characteristics

A

at least one active oncogene and the mutation of several tumor-suppressor genes

99
Q

Can a person inherit cancer genes?

A

Yes; they can inherit oncogenes or mutant alleles of tumor-suppressor genes

100
Q

Mutated gene in colorectal cancer?

A

adenomatous polyposis coli (tumor-suppressor)

101
Q

Mutated gene in breast cancer?

A

BRCA1 and 2

Biology 1113 (7 decks)

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