Brainscape's Knowledge GenomeTM

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


See full index

Genetics - 3500 > Midterm 3 > Flashcards

Midterm 3 Flashcards

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

What are the 3 ways eukaryotic gene regulation differs from bacterial regulation?

A
  1. Each structural gene has its own promoter, and is transcribed separately
  2. DNA must unwind from the histone proteins before transcription
  3. Transcription and translation are separated in time and space.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

T/F changes in chromatin structure affect the expression of genes.

A

True

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

What is histone modification?

A

Addition of methyl groups
(can cause condensation or relaxation of chromatin, depending on location of methyl groups)
OR
Addition of acetyl groups to histone proteins
(typically causes relaxation)

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

What is another word for the addition of methyl groups

A

Acetylation

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

Acetylation is associated with gene expression

A

True

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

What are the steps to acetylation?

A
  1. The chromatin remodeling complex binds to DNA
  2. This repositions nucleosomes, exposing a transcription factor binding site
  3. Transcription factors and RNA polymerase bind to DNA and initiate transcription.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does acetylation lead to gene expression?

A
    • charged tails of histone interact with - charged DNA molecule
  2. Acetylation of these tails weakens these interactions and permits transcription factors to bind to DNA
    (Transcription factors activate gene expression)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is an example of acetylation in the real world?

A

In the flower Arabidopsis, two genes interact (FLC & FLD)
FLC: Makes protein that binds to DNA and turns off flowering
FLD: protein that removes acetyl groups from histone protein surrounding FLC gene. Thus FLC is compacted densely and will not transcribe.
SOOO.. In acetylation FLC is repressed therefore it cannot shut off flowering and flowering occurs.

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

Chromatin remodeling plays a very important role in gene expression!!!

A

TRUE

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

What complexes bind directly to DNA sites and reposition nucleosomes by remodeling chromatin?

A

Chromatin-remodeling complexes.

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

What is DNA methylation also referred to?

A

CpG island

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

What occurs during DNA methylation?

A

DNA methylates cytosine bases adjacent to guanine nucleotides.
This represses transcription until it is removed.

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

What is the role of transcriptional activators and coactivators in gene expression?

A

They stimulate and stabilize the basal transcription apparatus at the core promoter

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

What happens with the GAL system in yeast?

A
  • GAL4 protein binds to DNA called upstream activation sequence, this activates gene expression of genes involved in galactose metabolism
  • GAL80 binds to GAL4 to stop it from doing its job.
  • Galactose allows GAL3 protein to bind to GAL80 to stop it from stopping GAL4
  • This allows GAL4 to interact and activate gene expression
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are transcriptional repressors and what do they do?

A

They stop transcription from occurring by binding to silencers

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

What are the roles of enhancers and insulators?

A

Enhancers: DNA sequence stimulating transcription from a distance away from promoter
Insulators: DNA sequence that blocks or insulates the effect of enhancers
- Insulators prevent the enhancers from doing something they aren’t supposed to
(insulator + binding protein)

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

What performs coordinated gene regulation and why:

A

Response elements when they want multiple sites to be turned on at the same time
(upstream of start sites that are to be turned on in response to the same element)

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

How can gene regulation be regulated after transcription?

A

RNA splicing
Example in drosophila
( Female functional Sxl gene leads to correct and functional splicing and Tra protein so female flies produced
whereas in man Sxl protein is infunctional so splicing is not the same so Tra not produced and fly is male)

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

What are 3 mechanisms of gene regulation caused by RNA interference?

A
  1. RNA Cleavage
  2. Inhibition of translation
  3. Transcriptional silencing: altering chromatin structure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What happens in RNA cleavage?

A
  • double stranded RNA is cleaved by the enzyme dicer to produce small interfering RNAs (siRNAs)
  • siRNAs combine with RISC complex and pair with complementary sequences
  • complex leaves mRNA therefore degradation occurs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What happens in inhibition of translation?

A
  • Single RNA molecular cleaved by dicer, these are microRNAs.
  • mirRNAs combine with RISC but pair imperfectly.
  • Not cut but inhibited.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Operons uncommon in eukaryotic expression

A

true

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

Initiation of transcription is relatively complex in eukaryotes

A

true

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

What is epigenetics?

A

Variation in a phenotype that is not caused by differences in the DNA sequence
- often caused by changes to chromatin some of which are heritable

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

What is DNA methylation?

A

Addition of methyl groups to nucleotide bases (often C)

  • most often causes gene silencing
  • can be maintained during DNA replication and transfer from parent to progeny
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

DNA methylation and honeybees

A
  • Queen (fertile) and workers (sterile) are both female
    Royal jelly, fed to larvae, silence a methyltransferase, prevents methylation (induces fertility)
  • this activates embryo into queen.
    -regular bee food allows methylation. –> genes repressed, therefore worker bee!
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Histone modifications can lead to epigenetic changes.

A

-More than 100 different modifications.
-Some can be maintained during DNA replication.
Perhaps the marks on original histones could be used to mark new ones?

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

Epigenetics effects RNA molecules

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is X inactivation?

A

One of the 2X chromosomes is turned off. Xist silences the chromosome. Different Xs are inactivated in different cells.
Tortoise shell cat: different follicles are different x inactivation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is an interaction between two alleles that can lead to a heritable change in expression of one alleles?

A

Paramutation

-wild type silencing in heterozygous individuals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is behavioral epigenetics?

A

Life experiences early on in life that have long lasting effects on behaviors.

  • epigenetic changes can be induced by:
    1. maternal behavior
    2. early stress
    3. abuse
    4. diets
    5. environmental chemicals
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Genomic imprinting is:

A

the idea that different genes are imprinted in egg v sperm cells.
(mom wants to slow development so speedy development genes are imprinted,
dad wants to speed up development so slow development genes are imprinted)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the difference between discontinuous (qualitative) traits and continuous (quantitative) traits?

A

discontinuous (qualitative) traits possess only a few phenotypes
continuous (quantitative) traits vary along a scale of measurement with many overlapping phenoytpes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is an example of qualitative traits?

A

short, or tall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is an example of quantitative trait?

A

human height

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Something important to remember***

A

Just because you can use a number to value a particular trait, doesn’t mean it’s quantitative in the sense we’re using it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What are characteristics of quantitative traits?

A

−Exhibit complex relationship between genotype and phenotype
−May be influenced by multiple genes (polygenic)−May be influenced by environment
−Phenotypic ranges may overlap
−Cannot use standard methods to analyze

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What are the types of quantitative characteristics?

A
  • Meristic

- Threshold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What are meristic characteristics?

A

−Determined by multiple genetic and environmental factors, and can be measured in whole numbers.
−Animal litter size.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What are threshold characteristics?

A

−Measured by presence or absence

−Susceptibility to disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

T/F Quantitative Characteristics Vary Continuously and Many Are Influenced by Alleles at Multiple Loci

A

TRUE*** KNOW THIS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What is meant by polygenic inheritance?

A
  • Refers to quantitative characteristics controlled by cumulative effects of many genes.
  • Each character still follows Mendel’s rules.
  • May be influenced by environmental factors.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

How can you calculate the amount of genes that control variation in a trait?

A 
(1/4)n = number of individuals in the F2 progeny that resemble each of the homozygous parents
–n = number of loci with a segregating pair of alleles that affects the characteristic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What does it mean when two characteristics are correlated?

A

a change in one characteristic is likely to be associated with a change in the other.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What does a correlation coefficient measure?

A

the strength of their association
- ranges from -1 to 1

  • negative values mean that as one trait increases, the other tends to decrease (inverse correlation)
  • positive values mean that as one trait increases, so does the other (positive correlation)
  • 0 means there is no correlation between the two traits
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

positive correlation

A

/ as one increases, the other will follow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

negative correlation

A

\ inverse association between variables

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

correlation of zero

A
49
Q

regression line best fits all the points on the graph.

A

true ;)

regression coefficient represents the slope of the regression line

50
Q

An individual’s phenotypic value equals the average, plus differences caused by genetic and environmental factors.
How would this be mathematically represented?

A

P = P + g + e

51
Q

Define heritability:

A

how much of the variation in a trait is genetic

52
Q

The amount of variation in a trait is the sum of genetic and environmental variation,
How would this be formulated mathematically?

A

Vp = Vg + Ve

53
Q

In a cross between homozygous recessive and dominant, the f1’s are genetically identical. Therefore any variation must be…..

A

environmental.
Vg= 0
Vp = 0 + Ve

54
Q

In a cross between homozygous recessive and dominant, the f1’s are genetically identical. But the f2s vary genetically.
Therefore any variation must be due to…

A

genetic and environmental variation

55
Q

What is broad sense heritability? (H2)

A

The proportion of the trait variation due to genetic variation
This is calculated by Vg/Vp

56
Q

What are operons?

A

a set of co-expressed genes, controlled by the same regulatory elements

57
Q

Are operons found in eukaryotes, prokaryotes, or both?

A

rare in eukaryotes, always in prokaryotes

58
Q

Define structural genes:

A

encoding proteins, often with enzymatic activity

59
Q

Define regulatory genes:

A

encoding products (ie. transcription factors) that interact with other sequences and affect the transcription and translation of these sequences

60
Q

Define regulatory elements:

A

DNA sequences that also play a role in regulating gene expression (often binding sites for transcription factors)

61
Q

How is transcription regulated?

A

DNA-binding proteins

Proteins that regulate transcription of a gene by binding to a regulatory element that controls that gene

62
Q

What is a set of co-expressed genes, controlled by the same regulatory elements

A

An operon

63
Q

What is the DNA sequence encoding products that affect the operon function, but are not part of the operon

A

A regulator gene

64
Q

How do we classify operons? (4 ways)

A

+ protein binding to DNA means gene is turned on
- protein binding to DNA means gene is turned off

  • inducible environmental signal (effector) turns gene “on”
  • repressible
    environmental signal (effector) turns gene “off”
65
Q

What happens in a negative inducible operon?

A 
Protein binding to DNA prevents gene expression
Small molecule (inducer) prevents protein from binding DNA, allowing gene to be turned on
66
Q

What happens in a negative repressible operon?

A

Protein binding to DNA prevents gene expression

Needs a small molecule (co-repressor) to allow it to bind DNA and turn the gene “off”

67
Q

What happens in a positive inducible operon?

A

Positive inducible operon
Protein binding to DNA turns gene “on”
Small molecule required to allow protein to bind

68
Q

What happens in a positive repressible operon?

A

Positive repressible operon
Protein binding to DNA turns gene “on”
Small molecule prevents protein from binding

69
Q
  • **JUST IMPORTANT INFORMATION

- Completely memorize.

A

The lac operon of E. coli is…

A negative inducible operon
Lactose metabolism
Regulation of the lac operon 
Inducer: allolactose
lacI: repressor encoding gene
lacP: operon promoter
lacO: operon operator

Structural genes
lacZ: encoding β-galactosidase
lacY: encoding permease
lacA: encoding transacetylase

The repression of the lac operon never completely shuts down transcription.

70
Q

More important information about E. Coli

A

Identify mutations that alter gene expression. Either
Z or Y off when they should be on
Z or Y on when they should be off

Which allele (wild-type or mutant) is dominant?
Problem – bacteria are haploid – only 1 copy of each gene
Solution – Use extrachromosomal DNA (F’ plasmid) to bring in a second copy

71
Q

What type of operon is the lac operon of e coli?

A

negative inducible operon

72
Q

What is the inducer of the lac operon?

A

allolactose

73
Q

lacI does what?

A

encodes for repressor protein

74
Q

what is lacP

A

the promoter

75
Q

what is lacO

A

the operator sequence that lacI binds to

76
Q

What are the structural genes?

A

lacZ: encoding B-galactosidase
lacY: encoding permease
lacA: encoding transacetylase (not necessarily needed)

77
Q

Which allele is dominant in e coli?

A

the wild type.

We found this by using extrachromosomal DNA (F’ plasmid) to bring in a second copy.

78
Q

Z+ is dominant to Z-,

why?

A

because we would essentially double the DNA, almost like across to see which would show up.
Therefore if you have the Z+ and the Z- and the Z+ shows up then we can assume that Z+ is dominant.

79
Q

Oc is what?

A

A constitutively active staring, that causes expression of Z and Y even without induction.

80
Q

FYI: If you see Oc then you can assume all plus signs.

A

TRUE

81
Q

FYI Oc is dominant to O+

A

TRUE

82
Q

FYI Oc (dominant allele) can only regulate the genes that are on the same strand as itself (cis acting)

A

TRUE

83
Q

FYI lacI- is recessive to lacI+

A

TRUE

84
Q

The dominant allele I+ can regulate genes on both strands (trans acting)

A

TRUE

85
Q

Summary of mutants:

A

lacI acts in trans, constitutive allele recessive

LacO acts in cis, constitutive allele dominant

86
Q

Is is a super repressor, what does this mean?

A

Mutants prevent expression of Z and Y even in presence of lactose.

87
Q

trp operon is….

A

negative repressible

88
Q

Define attenuation:

A

this affects the continuation of transcription, not its initiation

89
Q

secondary structure (folding) of the mRNA molecule is influence by….

A

levels of tryptophan in the cell.

90
Q

upstream of trp operon is..

A

5’ UTR

91
Q

when tryptophan level is high region 3 pairs with region 4 and transcription…

A

ends

92
Q

when tryptophan is low,

A

RNA transcription will continue

93
Q

which RNA molecules control the expression of gene expression?

A
  • antisense RNA: RNA’s that are complementary to mRNA
  • riboswitches
  • ribozymes: catalytic activity
94
Q

Name and explain the 5 main evolutionary forces that can cause H-W disequilibrium.

A
  • migration
  • mutation
  • non random mating
  • genetic drift
  • selection
95
Q

In this population, which characteristic would respond BEST to selection?

A

The one with the highest narrow-sense heritability

96
Q

Narrow-sense heritability is due to what type of genetic variance?

A

additive genes

97
Q

Why does the response to selection often level off after many generations of selection?

A

Eventually, everyone is homozygous for the selected allele, plus there might be detrimental effects of having a phenotype too extreme.10.

98
Q

Why is the relation between genotype and phenotype frequently complex for quantitative characteristics?

A

Because many genes can influence the phenotype, as can environmental factors.

99
Q

Will a worker or queen bee have more copies of 5-methylcytosine in their DNA? Why?

A

Workers. Royal jelly fed to larvae meant to be queens silences methyltransferase Dnmt3 and prevents methylation of cytosine.

100
Q

How do epigenetic traits differ from traditional genetic traits, such as the differences in color and shape of peas that Mendel studied?

A

Epigenetic traits are stably heritable phenotypes resulting from changes in chromosome without alterations in the DNA sequence

101
Q

What is the genomic conflict hypothesis for the origin of genomic imprinting?

A

Imprinting grew out of a competition between males and females for maternal resources.

102
Q

How is X inactivation an epigenetic phenotype?

A

An example of RNA molecules affecting the phenotypes produced by the chromosomes.

103
Q

Where is DNA methylation usually found?

A

On the 5 position of cytosine.

104
Q

Suppose a geneticist introduced a small interfering RNA (siRNA) that was complementary to the FLC mRNA in the provided figure. What would be the effect on the flowering of Arabidopsis?

A

siRNA would interfere with the transcription of FLC and would allow flowering of the Arabidopsis.

105
Q

Discuss the role of alternative splicing in the control of sex differentiation in Drosophila?Discuss the role of alternative splicing in the control of sex differentiation in Drosophila?

A

n XX embryos, the Sxl gene produces a protein that splices Tra pre-mRNA so that Tra protein is made. With Tra-2 protein, the two direct female specific splicing of dsx pre-mRNA and the fly develops into a female.In XY the Sxl gene is not active and Tra pre-mRNA is spliced differently so that no functional Tra protein is made. Without the Tra protein, male-specific splicing of dsx pre-mRNA occurs and a male develops.

106
Q

How do response elements bring about the coordinated expression of eukaryotic genes?

A

Response elements work within a genes promoter and can respond to environmental conditions to increase transcription. When the same element is in different genes, they get activate simultaneously by the same stimuli and create a coordinated response.

107
Q

What is an insulator?

A

Insulators work to block enhancer elements.

108
Q

How does an enhancer affect the transcription of distant genes?

A

Enhancers bind to transcription factors that can enhance the frequency of transcription for a gene.

109
Q

How do transcriptional activator proteins and repressors affect the level of transcription of eukaryotic genes?

A

Activator proteins activate or co-activate transcription. Repressors block transcription.

110
Q

How does DNA methylation affect transcription?

A

Methyl groups may prevent the binding of transcriptional factors – gene silencing.

111
Q

How does histone acetylation affect chromatin structure and transcription?

A

Acetyl groups are attached to positively charged lysines in histone tails. This loosens chromatin structure and promotes initiation of transcription.

112
Q

If negative is mutated all will be…

A

ON

113
Q

if positive operon is mutated, all signals will be turned..

A

OFF

114
Q

initially in a negative repressible operon the gene will be…

A

on when signal absent and off when signal present

115
Q

initially in a negative inducible operon the gene will be…

A

off when signal absent and on when signal present

116
Q

initially in a positive repressible operon the gene will be…

A

on when signal absent and off when signal present

117
Q

initially in a positive inducible operon the gene will be

A

off when signal absent and on when signal present

118
Q

initially in an INDUCIBLE operon the gene will be…

A

off when signal absent and on when signal present

119
Q

initially in a REPRESSIBLE operon the gene will be

A

on when signal absent and off when signal present

Genetics - 3500 (4 decks)

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