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Molecular Cell Biology > Test 2 > Flashcards

Test 2 Flashcards

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0
Q

When the glucocorticoid hormone binds, what happens?

A

The glucocorticoid receptor activates transcription of several genes involved in the glucocorticoid response to stress/exercise.

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1
Q

Transcription initation complex consists of:

A

Transcription regulators
General transcription factors
RNA polymerase

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2
Q

MyoD is a ________ _________ that commits cells to become __________.

A

Transcription regulator, myoblasts

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3
Q

________ can become myoblasts due to MyoD (immunostained w/ antibodies that detect muscle -specific proteins) expression.

A

Fibroblasts

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4
Q

Methylated sites on cytosine can ____ ______ gene expression. This is mechanism for inheritance of patterns if gene expression.

A

Turn off.

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5
Q

What is the germ line? Can that mutation be passed on to offspring of the individual?

A

The cell lineage in a multicellular organism that contributes to the formation of a new generation by producing gametes.

-yes, the mutation does not affect the individual in which it occurred but it is heritable.

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6
Q

What is a somatic cell? If a mutation occurs in a somatic cell, will it be passed on to offspring of the individual?

A
  • body cell

- only the progeny of the cell will be affected in the individual in which the mutation occurred.

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7
Q

What are the genetic changes that contribute to gene alteration and genome evolution?

A
  1. Mutation within a gene
  2. mutation in regulatory region
  3. gene duplication
  4. Mobile genetic elements
  5. Horizontal transfer
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8
Q

Mutation within a gene results in_____.

A

Altered product.

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9
Q

A mutation in a regulatory region results in an______.

A

Altered expression.

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10
Q

Genre duplications result in_____.

A

Beginning of a gene family.

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11
Q

Horizontals transfer results in_______.

A

Gene acquisition.

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12
Q

The presence of different regulatory DNA sequences in closely related spp results in:

A

The use of different developmental pathways.

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13
Q

What are gene families? And how are the related genes related ?

A

Groups of genes that originate by duplication from a common ancestor.

Family members are similar in structure and function.

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14
Q

Describe the global gene family.

A
  • multiple diff. genes code for hemoglobin subunits.
    -diff. members are expressed during diff life stages.
    -include pseudogenes
    -
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15
Q

What is a heme group?

A

Iron containing molecule in globin in subunit that contains the binding site for Oxygen.

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16
Q

What does hemoglobin transport in the circulatory system?

A

CO2 and O2

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17
Q

What and how many subunits does the adult hemoglobin contain?

A

2 alpha

2 beta

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18
Q

What are the difference between the different globin proteins?

A

They have different affinities for O2.

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19
Q

Short repeated sequences within homologous chromosomes cays what?

A

Misalignments and unequal crossing over which results in gene duplication

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20
Q

What are short repeated sequences?

A

Non coding conserved sequences that are scattered through out the genome.

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21
Q

What affect does unequal crossing over have on chromosomes?

A

Altered size and genetic content.

  • one chromosome has an extra copy of the gene
  • one chromosome lost the gene.
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22
Q

X. tropicalis has a ________ genome. (Frog)

A

Diploid

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23
Q

X. lavis has a ________ genome as a result of of duplication of the whole genome.

A

Tetraploid

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24
Q

The doubling of a genome results because of what? And is the doubling of the gene passed on?

A

Results if a germ cell fails to divide after DNA replication.

-may be passed on to games and eventually to the progeny.

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25
Q

What can mediate gene rearrangement?

A

The transposition of eukaryotic Mobile genetic elements.

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26
Q

Describe exon transposition

A

When similar mobile genetic elements insert near each other on the same chromosome, a transposition mechanism may use the ends of the 2 different elements, resulting in transposition of the entire segment of the chromosome between 2 mobile elements.

If the segment includes an exon, it’s insertion would create a new version of that gene.

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27
Q

The transposition of eukaryotic mobile genetic elements can alter_______, which can alter the tissue-specific pattern of gene expression.

A

Regulatory sequences.

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28
Q

In fruit flies, what gene is ectopically expressed in the head as a result of the a mobile genetic element (p-element) inserting into this gene’s regulatory sequence?

A

Antennapedia

Antenna are transformed into legs.

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29
Q

What is homeotic transformation?

A

One body part is replaced by a body part normally found in another region.

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30
Q

What is conjugation? And what is its result?

A

Conjugation is the transfer if genetic info (via a plasmid) from one cell to another through a sex pilus.

The result is genetic recombination without reproduction.

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31
Q

Fibroblasts and myoblasts are both derived from the _________ _________.

A

Embryonic mesoderm.

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32
Q

What are three mechanisms of inheritance of patterns if gene expression?

A
  1. +feedback loop involving transcription regulators.
  2. Preservation of covalent histone modifications and chromatin condensation patterns.
  3. Preservation if DNA methylation patterns.
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33
Q

What is passed on to daughter cells in a positive feedback mechanism for inheritance of gene expression?

A

Transcription regulators.

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34
Q

What is the function of tissue-specific histone binding enzymes?

A

This enzyme is preserved through out cell devision and is passed on to daughter cells. The enzyme restores the parent pattern of histone modification and chromatin condensation.

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35
Q

What happens when specific GC sequences are methylated?

A

These methylated sites turn off gene expression by attracting proteins that block transcription.

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36
Q

After DNA is replicate which strand is the only one methylated?

A

Parent/template

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37
Q

What enzyme recognizes already methylated GC sequences and catalyzes the methylation of corresponding GC sequences in the new DNA strand?

A

Maintenance methytransferase

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38
Q

How is the DNA methylation pattern preserved?

A

Maintenance methyl transferase is passed on to the daughter cells.

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39
Q

What transcription regulator in Drosphila controls the expression of many different genes and can also induces the expression of additional transcription regulators including itself?

A

Eyless

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40
Q

The Eyeless gene in fruit flies is similar to what gene in mice and humans?

A

Pax-6

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41
Q

How do humans develop aniridia?

A

Heterozygous for pax-6 mutation

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42
Q

What is a phospholipid?

A

Polar (hydrophilic) head group and non-polar (hydrophobic) hydrocarbon tails (fatty acids).

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43
Q

In the fluid mosaic biological membrane in what way do lipids and proteins diffuse?

A

Laterally.

44
Q

The cellmbrane is fluid, it’s course parts can move in what ways?

A

Flexion, rotation,

45
Q

Identify the structures if a phospholipid:

A
  1. Hydrophobic head–> polar group, phosphate, glycerol

2. Two hydrophobic fatty acid tails.

46
Q

Describe the structure of cholesterol:

A
  1. Polar head group- OH

2. Nonpolar groups: steroid ring structure and hydrocarbon tail.

47
Q

How does cholesterol function?

A

Modulated membrane fluidity.

  • high temps, cholesterol restrains movement. (Maintains stability)
  • at low temps, cholesterol prevents right packing of fatty acids. (Maintains fluidity)
48
Q

Glycolipids are ways found where? And and do what?

A

They are always found in the outer layer of the membrane.

They are cell identity markers.

49
Q

Charged phospholipids (phosphatidylinsotol and phosphatidyserine) are always found where? And what is an exception?

A

Inner layer of the membrane.

Except for when an enzyme is activated to flip the charged particle to result in cell death.

50
Q

What are the protein components of the cell membrane?

A

Transporters –> carrier proteins and ion channels

Anchors–> integrins

Surface receptors–> hormone receptors

Enzymic proteins–> tyrosine kinases

51
Q

Glycoproteins, proteoglycans, and glycolipids form what?

A
  1. Protective carbohydrate layer

They are cell identity markers.

52
Q

What surface receptors do endothelial cells express in responses to signals from infected tissue?

A

Lectin

53
Q

Small hydrophobic molecules that can diffuse across a membrane:

A

O2, CO2, N2, benzene

54
Q

Small uncharged molecules that can diffuse across a biological membrane:

A

H2O, glycerol, ethanol

55
Q

Large uncharged polar molecules that can’t diffuse across a membrane:

A

Amino acids, glucose, nucleotides

56
Q

Ions that can’t diffuse across a membrane:

A

H+, Na+, HCO3-, K+, Ca2+, Cl-, Mg2+

57
Q

In the ear, what collects sound waves? And were are the sound waves concentrated?

A

-they are collected in the auditory canal and concentrated at the tympanic membrane

58
Q

The tympanic membrane is also known as:

A

The ear drum

59
Q

After concentration, the sound waves are then relayed through what?

A

Through three auditory ossicles: malleus, incus, and stapes.

60
Q

Vibrations from the auditory ossicles are received by the _______ through the_____________.

A

Cochlea, oval window.

61
Q

What is the oval window?

A

The interface between the air in the middle ear and the fluid mosaic in the cochlea.

62
Q

Sound waves travel as pressure waves though the _____ ____ inside the _____ _____, then return through the tympanic duct and are dissipated through the ______ ________.

A

Perilymph fluid,
Vestibular duct,
Round window

63
Q

How does the neurotransmission of hearing impulses begin?

A

With the opening of mechanically-gated potassium channels.

64
Q

Which ion flows into the sterocillia thereby initiating the hearing sensation?

A

K+

65
Q

What is membrane potential? How is it established?

A

(Vm)The voltage across the membrane

It’s established by the charge difference between the two sides of the membrane.

Measured in mV.

66
Q

When a nerve is at rest, what is the membrane voltage at? Are the voltage gated Na+ channels open or closed?

A

Membrane voltage: -80 mV (cell is -)

Channels are closed.

67
Q

Durning the rising phase of a nerve cell, what happens?

A

A depolarizing stimulus current causes the membrane to reach the threshold potential (-60 mV) which opens the Na+ channels. Leading to action potential.

68
Q

What is action potential?

A

When and influx of Na+ Channels causes the membrane to depolarize to +40 mV

69
Q

What do voltage-gate Na+ channels become inactivated?

A

At the peak of action potential 40mV

70
Q

A membrane returns to resting potential due to what?

A

The opening voltage gate k+ channels and the activity of the Na/K pump. Allows K to leave the cell.

71
Q

What happens at the end of the falling phase?

A

Voltage gate Na and K channels close.

72
Q

The phosphorylation of the Na/K pump causes what?

A

A conformational change that releases the Na+ ions to the outside cell.

73
Q

Dephosphorylation of the of the Na/K pump causes what?

A

The return of the original conformation and the release of K+ ions inside the cell.

74
Q

What causes cystic fibrosis?

A

A point mutation in an ATP-dependent Cl- ion transporter that alters the ionic gradients of several types of cells, which effects the cells osmotic balance.

Mutations cause disrupt the folding of the CFTR protein

75
Q

CFTR protein

A

Cystic fibrosis transmembrane conductance regulator.

76
Q

Where do all reactions of glycolysis occur?

A

Cytoplasm

77
Q

What is substrate level phosphorylation?

A

The transfer of a phosphate from a sugar intermediate to ADP.

78
Q

What happens when glucose is transformed to glucose 6-phosphate?

A

ATP is consumed and hydrolyzed and glucose is phosphorylated.

79
Q

Describe what takes places starting with glucose6-phosphate going to fructose 6-phosphate?

A

Isomerizarion of G6P

80
Q

Describe the reaction to obtain fructose 1, 6-bisphosphate

A

Phosphorylation of F6P at C1. ATP is consumed. Unreversible.

81
Q

How are dihydroxyacetone phosphate and glyceraldehyde 3-phosphate obtained?

A

From the cleavage of FBP. Reversible.

DHP needs to undergo isomerization to become GAP.

82
Q

Describe the reaction to get from glyceraldehyde 3-phosphate (GAP) to 1,3-bisphospopholycerate.

A

GAP is oxidized, 2NAD+ reduced to 2NADH, P is attached to C1. Reversible

83
Q

Describe the reaction from 1-3BPG to 3-phosphoglycerate:

A

P is transferred from BGP to ADP, 2 ATP are synthesized by substrate level phosphorylation. Reversible

84
Q

Isomerization of 3PG yields what? Describe the free energy.

A

2- phosphoglycerate low free energy. Reversible.

85
Q

Dehydration of 2PG yields what?

A

Phosphoenolpyruvate. High energy. 2 H2O are removed. Reversible.

86
Q

Describe the creation of puruvate from the previous molecule.

A

Transfer of P from PEP to ADP. 2 ATP are synthesized by substrate level phosphorylation.

87
Q

Net yield of glycolysis:

A

2ATP+2NADH

88
Q

What happens to pyruvate in muscle cells in the absence of oxygen?

A

2 pyruvate molecules are reduced by 2 NADH—> 2 lactate molecules and NAD+

89
Q

What happens to pyruvate in yeast?

A

2 CO2 are removed—> 2 acetaldehyde

2 acetaldehyde+ 2 NADH–> 2ETOH +NAD +

90
Q

When O2 is present, where are pyruvate and NADH transported?

A

The mitochondria.

91
Q

What happens to pyruvate after it has been taken into the mitochondria?

A

Pyruvate is oxidized and converted to acetyl coenzyme A and enters the citric acid cycle.

92
Q

What is oxidative phosphorylation? And what powers it?

A

The electron transport chain. NADH

93
Q

Where in the mitochondria does the oxidation of pyruvate and the citric acid cycle occur?

A

The matrix

94
Q

What occurs in the inner membrane of the mitochondria?

A

Electron transport chain and oxidative phosphorylation.

95
Q

How is acetyl CoA produced?

A

Pyruvate+ CoA –> 2acetyl CoA+ CO2

Condensation

CO2 is removed via hydrolysis

96
Q

acetyl CoA(2C)+ Oxaloacetate(4C)–>

A
  1. Citric acid (6C)

Condensation and citrate synthesis.

Hydrolysis removes CoA which drives the reaction forward.

97
Q

2 (cac). Citric acid + isomerization–>

A

Isocitrate

98
Q
  1. Isocitrate (6C) + NAD+——>
A

Alpha-ketoglutarate (5C) + CO2+ NADH+ H

99
Q
  1. Alpha-ketoglutarate+ CoA + NAD+ —>
A

Succinyl CoA + CO2 + NADH

100
Q
  1. Succinyl CoA+ h2o+ P+ GDP–>
A

Succinyl (4C) + GTP + ATP synthesis

101
Q
  1. Succinate (4C) + FAD —>
A

Fumerate (4c) + FADH2

102
Q
  1. Furamate+ h2o–>
A

Malate (4C)

103
Q
  1. Malate + NAD+ –>
A

Oxaloacetate ( 4C)

Re enters the cycle.

104
Q

Yield of the citric acid cycle 2x

A

4CO2
6NADH
2FADH2
2ATP

105
Q

When H+ flows back into the matrix of the mitochondria, what happens?

A

ATP synthesis

106
Q

What powers the H+ pumps?

A

Oxidation NADH and FADH2

107
Q

NADPH

A

Electron carrier in photosynthesis

Molecular Cell Biology (2 decks)

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