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AP Biology > Chapter 15 > Flashcards

Chapter 15 Flashcards

1
Q

Natural selection has favored bacteria that produce?

A

only the gene products needed

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2
Q

Gene expression in bacteria is controlled by a mechanism known as?

A

operon model

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3
Q

operon

A

a single promoter serves a set of functionally related genes

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4
Q

The functionally related genes of an operon can be coordinately controlled by?

A

a single on “on-off” switch

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5
Q

operator

A

segment of DNA that is a regulatory switch

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6
Q

The operon stretch of DNA includes?

A

operator, promoter, genes that promoter/operator control

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7
Q

How can operon be switched off?

A

protein repressor

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8
Q

The repressor binds to the ___ and ____

A

operator, blocks the attachment of RNA polymerase

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9
Q

The repressor is the product of?

A

a seperate regulatory gene not part of the operon

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10
Q

repressor can be in ___ or __

A

inactive or active form

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11
Q

corepressor

A

molecule that cooperates with a repressor to switch operon off

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12
Q

example of repressible operon

A

tryptophan

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13
Q

The trp operon is ___ and the genes for trp synthesis are ___ because ___

A

on, transcribed, it is an amino acid and bacteria need proteins

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14
Q

When trp is present, it binds to the ___ protein which then turns ___

A

trp repressor, the operon off

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15
Q

A repressible operon is one that is usually __

A

on

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16
Q

A inducible operon is one that is usually __

A

off

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17
Q

example of inducible operon

A

lac operon

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18
Q

By itself, the lac repressor is __ and switches __

A

active, the lac operon off by binding to operator

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19
Q

inducer

A

inactivates the repressor to turn the lac operon off

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20
Q

lac operon inducer is?

A

allolactose

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21
Q

Inducible enzymes

A

enzymes of lactose pathway

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22
Q

Repressible enzymes

A

enzymes of trp pathway

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23
Q

repressible enzymes usually function in ___ and their synthesis is ___

A

anabolic pathways, repressed by high levels of their end product

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24
Q

inducible enzymes usually function in?

A

catabolic pathways

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25
regulation of lac and trp operons involves ___ of genes because operons are ___
negative control, switched off by active form of repressors
26
When glucose is scarce, __ acts as an ___
cAMP receptor proteins, activator of transcription
27
CRP is activated by binding with?
cyclic AMP
28
Differences between cell types result from?
differential gene expression
29
differential gene expression
expression of different genes by cells with same genome
30
Gene expression is regulated at many?
stages
31
gene expression is commonly controlled at?
transcription
32
Greater complexity provides opportunities for regulating?
gene expression at stages other than transcription
33
What can influence gene transcription?
location of gene promoter relative to nucleosomes
34
Genes within ___ are usually not expressed?
heterochromatin
35
histone acetylation
acetyl groups attach to amino acids in histone tails
36
DNA methylation
addition of menthyl groups which can lead to reduced transcription.
37
Once methylated genes usually?
remain menthylated through cell divisions
38
After replication, enzymes methylate the correct daughter strand so that?
methylation pattern is inherited
39
epigenetic inheritence
inheritence of traits transmitted by mechanisms not directly involving nucleotide sequence
40
epigenetic modifications can be?
reversed
41
Associated with most eukaryotic genes are multiple?
control elements
42
control elements
segments of noncoding DNA that serve as binding sites for transcription factors
43
control elements and transcription factors are critical for?
precise regulation of gene expression
44
general transcription factors act at?
promoter of all genes
45
some genes require?
specific transcription factors that bind to control elements
46
distal control elements are ___ and proximal control elements are ___.
enhancers, promoters
47
In eukaryotes, the precise control of transcription depends on?
binding of activators to control elements
48
eukayotic genes that are ___ are not ____.
co-expressed, organized into operons
49
eukayotic coexpressed genes are?
scattered over different chromosomes
50
To mark a particular protein for destruction, the cell commonly attaches molecules of?
Ubiquitin
51
Protein coding DNA accounts for only __ of the human genome
1.5%
52
What plays a crucial role in regulating gene expression?
large and diverse population of RNA molecules
53
Micro RNAs
small, single stranded RNA molecules that can bind to mRNA sequences
54
miRNAs can ___ mRNA or block its ___.
degrade, translation
55
What is another class of small RNAs?
small interfering RNAs (siRNAs)
56
siRNAs and miRNAs are similar but?
form from different RNA precursors
57
RNA interference
phenomenon of inhibition of gene expression by siRNAs
58
In some yeasts siRNAs are required for the formation of?
heterochromitin at centromeres of chromosomes
59
siRNA system interacts with ___ and ____.
noncoding RNAs, chromatin-modifying enzymes
60
What also induces formation of heterochromatin?
piwi-associated RNAs (piRNAs)
61
piwi-associated RNAs (piRNAs)
block expression of transposons
62
Most straight forward way to discover which genes are expressed by cells of interest?
identify the mRNAs being made
63
We can detect mRNA in a cell using?
nucleic acid hybridization
64
nucleic acid hybridization
base pairing of a strand of nucleic acid to its complementary sequence
65
nucleic acid probe
complementary molecule or a short stranded DNA or RNA
66
in situ hybridization
The nucleic acid probe is tagged with fluorescence which allows us to see the mRNA.
67
Another method used for comparing the amounts of specific mRNAs?
reverse transciptase-polymerase chain reaction (RT-PCR)
68
Reverse transcriptase-polymerase chain reaction (RT-PCR)
turns sample set of mRNAs into double stranded DNAs
69
complementary DNA (cDNA)
DNA copy of an mRNA
70
DNA microarray assays
tiny amounts of many single stranded DNA fragments on a slide in a grid are studied for genome-wide expression
71
RNA sequencing (RNA-seq)
sequence cDNA samples from different tissues or stages to discover which genes are expressed.

AP Biology (19 decks)

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