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Biology > BIO202 Exam 4 > Flashcards

BIO202 Exam 4 Flashcards

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1
Q

What is the trp operon?

A

A gene that codes for the amino acid tryptophan. It’s turned off when tryptophan levels are high and turned off when they are low.

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2
Q

What regulates the trp operon?

A

Tryptophan levels and the trp repressor. When the trp repressor is bound to tryptophan, operon expression is blocked

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3
Q

What regulates tryptophan biosynthesis?

A

The trp operon and attenuation

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4
Q

Silent mutation

A

When a change in a nucleotide pair transforms one codon into another that is translated into the same amino acid. Results in no observable change on the phenotype.

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5
Q

missense mutation

A

Substitutions that change one amino acid into another.

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6
Q

nonsense mutation

A

When a point mutation changes a codon for an amino acid into a stop codon

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7
Q

mutagens

A

physical and chemical agents that interact with DNA and cause mutations

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8
Q

reciprocal translocation

A

parts of two non-homologous chromosomes are switched

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9
Q

TATA box

A

A sequence of nucleotides found at the promoter of eukaryotes. It plays an important role in forming the transcription initiation complex by binding a general transcription factor. The binding of the general transcription factor to the TATA box allows for RNA pol II to bind correctly for transcription.

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10
Q

Point mutation

A

The substitution of one nucleotide base in DNA for another

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11
Q

Nucleosome

A

DNA wound around a core of histones

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12
Q

Activators

A

Specific proteins which enhance transcription in eukaryotes. They bind control elements in enhancers, mediator proteins, and general transcription factors.

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13
Q

Splicing

A

Takes place after transcription and is one way the pre-mRNA is processed to prepare the mRNA for translation. Spliceosomes proteins remove introns.

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14
Q

Enhancers

A

Regulate transcription by enhancing the activity of RNA-polymerase at a single promoter site.

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15
Q

gene regulation

A

determining which genes are expressed

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16
Q

Operons

A

Exist in bacteria but not in eukaryotes. They are a cluster of genes coding for proteins that function together

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17
Q

Properties of operons

A

Genes are adjacent and have a single promoter. 1 mRNA is made that codes for several proteins.

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18
Q

Transcription

A

RNA polymerase binds to a promoter and moves down the gene to make RNA

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19
Q

polycistronic mRNA

A

codes for more than one protein (bacteria)

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20
Q

monocistronic mRNA

A

codes for 1 protein (eukaryotes)

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21
Q

Operator

A

DNA region between the promoter and the first gene of the operon (only in bacteria)

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22
Q

Where are operons located?

A

Only in bacteria

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23
Q

Repressor proteins

A

Can inhibit transcription by binding operator and blocking RNA polymerase. They are examples of regulator proteins.

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24
Q

Regulator proteins

A

Bind DNA and affect transcription

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25
Q

Who is tryptophan made?

A

In E. coli it is made by a biochemical pathway. A precursor compound is converted to trp by a series of steps - each catalyzed by an enzyme.

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26
Q

Where do the enzymes needed for trp synthesis come from?

A

A different gene codes for each one

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27
Q

When is the Trp operon expressed?

A

Only if Trp is not available in the environment

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28
Q

Trp repressor

A

It is specific for the Trp operon and it will always bind Trp if it is available. Binding changes the repressor’s conformation.

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29
Q

When does Trp repressor bind to the operator?

A

Only when it is bound to Trp

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30
Q

Mutation

A

uncorrected error in DNA sequence

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31
Q

Insertion or deletion

A

One or more bases is added or left out

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32
Q

Effect of missense mutation

A

When a point mutation changes that amino acid sequence, it can have a large/small effect on protein function or no effect at all.

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33
Q

Sickle cell disease

A

Caused by a missense mutation on the beta-globin gene

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34
Q

Frameshift mutations

A

Change a reading frame and they drastically change the amino acid sequence and are very serious.

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35
Q

Reading frame

A

Division of bases on a strand into codons

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36
Q

Insertions or deletions

A

Extra or missing nucleotides. Unless they occur in multiples of 3, they are frameshift mutations

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37
Q

Alterations in chromosome structure

A

Result from abnormal chromosomes breakage; not crossing over in meiosis

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38
Q

Deletion

A

Part of the chromosome is lost

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39
Q

Duplication

A

Part of the chromosome is duplicated

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40
Q

Inversion

A

Part of the chromosome is turned backwards

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41
Q

Translocations can lead to

A

cancer

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42
Q

Transcription initiation complex

A

RNA pol. and transcription factors

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43
Q

Control elements

A

Specific transcription factors that bind to DNA at sequences and help the initiation complex bind the promoter

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44
Q

Proximal control elements

A

Close to the promoter

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45
Q

Distal control elements

A

They’re far from the promoter. Groups of these are called enhancers

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46
Q

Enhancers

A

Groups of distal control elements

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47
Q

Activators and repressors in eukaryotic cells

A

Specific transcription factors that bind enhancers to control gene expression

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48
Q

DNA-bending proteins

A

bring activators close to the promoter. Activators can bind general transcription factors and mediator proteins.

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49
Q

Tissue specific transcription factors

A

Are only present in some cells. Genes they regulate are only expressed in those cells. Unless needed, activators for certain genes are not present.

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50
Q

Combinatorial control of gene activation

A

Several control elements regulate each gene. Different activators bind each one. Independent adjusting the levels of each activator can fine-tune the gene expressions

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51
Q

Coordinately-controlled genes

A

Each is associated with a separate copy of the same control element that binds the same activator.

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52
Q

SRE

A

Sterol response elements are associated with genes for cholesterol synthesis in human cells. Each has its own promoter and they’re on different chromosomes. Each gene s expressed only when cholesterol levels are low.

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53
Q

How is cholesterol produced in human cells?

A

When cholesterol levels are low genes for synthesis are expressed. An activator, SREBP binds to each SRE to stimulate transcription of that gene.

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54
Q

Coordinate expression

A

When genes are expressed together that produce the enzymes that work together

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55
Q

Histone tail acetylation

A

loosens chromatin and enhances transcription

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56
Q

Protein domains

A

Can fold independently and can contain different secondary structure elements. They can also have independent functions.

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57
Q

Proteins are mix and match combinations of different

A

domains

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58
Q

Exon shuffling

A

Can rearrange domains in new combinations making new genes

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59
Q

SH2 domain

A

binds phospho-tyrosine to another protein

60
Q

Helix-turn-helix

A

HTH domain that binds DNA

61
Q

All cancers

A

Have unregulated cell division and result from mutations

62
Q

PDGFR

A

PDGF reception is a receptor tyrosine kinase on the plasma membrane that binds PDGF (growth factor) in the bloodstream

63
Q

Constitutively-active mutants

A

Always have the active conformation; even without getting a signal. This can lead to unregulated cell division

64
Q

Oncoprotein

A

Constitutively active protein that can cause cancer

65
Q

Oncogene

A

mutated gene for protein

66
Q

Proto-oncogene

A

normal gene that becomes an oncogene when mutated

67
Q

Mutagens

A

agents causing mutations

68
Q

Carcinogens

A

can cause cancer

69
Q

p53

A

A transcription factor that stimulates production of proteins that slow the cell cycle (allow time for DNA to repair), repair DNA, and/or kill cell by apoptosis if damage is too bad.

70
Q

Genome projects

A

Sequencing the entire genome of a species

71
Q

Transposable elements

A

Can replicate and insert new copies in genome. (Rare) Have no known function and are probably parasites in our genomes.

72
Q

Transposons

A

Move in a genome by a DNA intermediate

73
Q

Retrotransposons

A

Move in a genome using a RNA intermediate. Most transposable elements in eukaryotic genomes are retrotransposons. Always remain in original site as well as inserting a copy in a new site.

74
Q

Transposon mobility

A

Sometimes called cut and paste (transposon is cut out of old site and moves into a new site in genome).

Sometimes called copy and paste (Transposon stays in the original site, but a copy is made and inserted in a new site)

75
Q

Reverse transcriptase

A

Retrotransposon is transcribed into RNA that codes for a protein: reverse transcriptase. It is translated and makes a complementary DNA copy of the RNA so it can be inserted into another site (Copy and paste).

76
Q

Retroviruses

A

Most likely derived from retrotransposons. DNA made enters the nucleus and inserts permanently into a chromosome. Then transcribed to make more viral RNA

77
Q

Multigene families

A

Groups of similar genes whose protein products perform related functions.

78
Q

Pseudogenes

A

Genes in the cluster that are never expressed. May have non-functional promoters.

79
Q

Unequal crossing-over

A

Chromosomes break and rejoin in different places. As a result, 1 chromosomes gets 2 copies of a gene and the other gets 0.

80
Q

Viruses

A

Infectious particles that contain ONLY a nucleic acid genome, a protein coat(capsid), and a few other proteins. They sometimes have a membrane envelope.

They can’t live independently. They must infect a host to reproduce.

81
Q

How do viruses function?

A

They take over host cell machinery for almost all steps in making new viruses. Host cell becomes a factory for virus production.

82
Q

RNA-dependent RNA polymerase

A

A special viral enzyme used to make complementary copies of viral RNA.

83
Q

Capsid proteins

A

viral proteins made on free ribosomes using host cell

84
Q

Glycoproteins

A

viral membrane proteins made on bound ribosomes. They’re transported to the plasma membrane in vesicles

85
Q

3 ways bacteria can acquire new DNA

A

Transformation, transduction, and conjugation.

86
Q

Transformation

A

Uptake of free DNA (bacteria)

87
Q

Transduction

A

bacteriophages carry DNA between cells

88
Q

Conjugation

A

“bacterial sex”; transfer of chromosomal DNA between bacteria from F+ cell OR Hfr cell to a F- cell.

The temporary joining of 2 bacteria by sex pili extending from 1 cell. Sex pilus usually breaks part way through the transfer and only part of the chromosome is transferred.

89
Q

Sex pilus

A

Hollow tube. DNA moves through it between cells.

90
Q

F (fertility) factor

A

Piece of DNA that codes for sex pilus proteins. ONLY bacteria with F factor make sex pili.

91
Q

Where do F factors exist?

A

They’re either integrated into the chromosomes or free as plasmids

92
Q

Plasmid

A

Small, circular self-replicating DNA that’s separate from the chromosome

93
Q

F+ cell

A

Has F factor as plasmid

94
Q

Hfr

A

Jas F factor in chromosome

95
Q

F- cell

A

Has NO F factor

96
Q

Nucleic acid probe

A

Short, synthetic, single-stranded DNA fragment complementary to the gene of interest

97
Q

PCR

A

Polymerase chain reaction can find the correct cDNA in a complex mixture and make many copies of it. (Used in insulin treatments for diabetes)

98
Q

What is the 3-step cycle that PCRs undergo?

A
  1. Heat: to denature (separate strands)
  2. Cool: primers bind template strands
    3: Extend: DNA polymerase makes a new strand, starting with the primer
99
Q

What is the 3-step cycle that PCRs undergo?

A
  1. Heat: to denature (separate strands)
  2. Cool: primers bind template strands
    3: Extend: DNA polymerase makes a new strand, starting with the primer
100
Q

Restriction enzymes

A

endonucleases that cleave DNA at specific sequences

101
Q

Plasmids

A

Replicate in bacteria and can accept foreign DNA fragments.

They can contain genes for antibiotic resistance that allow bacterial growth even with antibiotics.

102
Q

Separation using agarose gels

A

DNA fragments can be separated from each other based on length

103
Q

How are DNA fragments separated by length?

A

Using agarose gel and an electric field this can be done. All DNA fragments are negatively charged and move toward the anode. Short fragments can move through the gel faster than the long ones.

104
Q

Detecting DNA fragments in agarose gel

A

The gel is soaked in a fluorescent dye that binds the DNA

105
Q

Tube gels

A

Are used to separate fluorescently-labeled DNA fragments. The strands move down the tube with the longest labeled strands near the top and the shortest at the bottom

106
Q

How to detect DNA fragments in tube gels

A

A laser is passed through fluorescently-labeled DNA fragments and detects them as peaks.

107
Q

ddNTPs

A

dideoxy-NTPs can be added to a strand in order to determine a nucleotide sequence (by labeling them with a fluorescent dye). They lack the 3’OH but otherwise, it’s the same as a dNTP. They end the strand.

108
Q

Goal of genetically modified (transgenic) plants and animals

A
  • Disease resistance
  • Better nutritional properties
  • Faster growth
109
Q

Spermatogenesis

A

The formation of sperm. It occurs in the seminiferous tubules tightly packed in the testes.

110
Q

Seminiferous tubules

A

Immature sperm cells are at the outside of the tubule wall. They move inward as they mature, meiosis also occurs. Mature sperm are then release into the lumen of the tubules.

111
Q

Ovary

A

Where eggs form via oogenesis.

112
Q

Follicles

A

Layers of cells surrounding each egg in the ovary

113
Q

Ovulation

A

Each month 1 egg bursts from the follicle and is released into the oviduct

114
Q

Fertilization

A

fusion of two haploid gametes to give diploid zygote

115
Q

Where does fertilization occur?

A

In the oviduct. Then the zygote moves to the uterus for implantation

116
Q

Acrosome

A

vesicle in the head of sperm

117
Q

Acrosome reaction

A

Fusion of acrosome with plasma membrane of sperm (secretion of contents)

118
Q

Cortical reaction

A

blocks polyspermy which is lethal

119
Q

Cortical granules

A

Vesicles stored in the egg just under the plasma membrane. Release contents of the cortical granules cause material surrounding egg to lift egg surface and harden into fertilization envelope; blocks sperm

120
Q

blastomeres

A

new cells formed during cleavage of zygote

121
Q

morula

A

Solid ball of cells formed during cleavage

122
Q

blastula

A

Formed after cleavage when the cells move and embryo changes shape to a hollow ball of cells with lumen called a blastocoel

123
Q

blastocoel

A

lumen of blastula

124
Q

Gastrulation

A

When cells moves to change the shape of an embryo and form the gastrula. One side of blastula pushes in at blastopore. Continues to push in to form the archenteron

125
Q

What part of the body will the blastopore become?

A

The anus

126
Q

What part of the body will the archenteron become?

A

The digestive tract

127
Q

Meroblastic cleavage

A

off-center blastocoel

128
Q

Holoblastic cleavage

A

blastocoel in the center

129
Q

Where does cleavage occur in mammals?

A

In the oviduct

130
Q

Blastocyst

A

Human’s version of a blastula. It’s a hollow ball of cells with an inner mass inside and a trophoblast outside.

131
Q

Inner cell mass

A

The part of the blastocyst that undergoes gastrulation and becomes the whole embryo.

132
Q

Trophoblase

A

The part of the blastocyst that becomes part of the placenta

133
Q

Placenta

A

A combination of blood vessels from mother and embryo. Allows exchange of nutrients, wastes, and gases.

134
Q

Pattern formation

A

setting up basic body plan so tissues and organs develop in the right place

135
Q

Mutation of bicoid

A

destroys function and gives an embryo with two back ends (no front end)

136
Q

Embryonic lethal

A

A mutation that gives defective protein. As a result, organism dies early in development.

137
Q

Bicoid protein

A

A transcription factor that stimulates expression of certain genes that control segment formation.

138
Q

Segments

A

Basic units of pattern formation in flies (both embryo and adult) Adult structures develop from segments in the larva.

139
Q

Homeotic genes

A

Control development of each segment into an adult structure.

They form a gene family and code for transcription factors that share a short conserved sequence; homeobox that encodes a homeodomain

140
Q

Homeotic mutation

A

Yields a defective homeotic gene. If this happens, another homeotic gene takes over. As a result, one body part is substituted for another.

141
Q

Stem cells

A

Undifferentiated cells that can differentiate into other cell types

142
Q

Embryonic stem cells

A

Cells from blastocyst that can differentiate into all tissues

143
Q

Totipotent cells

A

can give rise to all cells of an adult

144
Q

Pluripotent stem cells

A

Are present even in adults. They can differentiate into some but not all cells types.

145
Q

Master regulatory genes

A

protein products commit a cell to a particular fate

Biology (6 decks)

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