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genetics > Chapter 7 > Flashcards

Chapter 7 Flashcards

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Biology 101 flashcards
1
Q

The process of alteration of a gene or chromosome, or the end-product of this process

A

mutation

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2
Q

mutations can affect genes from one allele (one form of a gene) to another, and thus produce a “mutant” _________

A

phenotype

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3
Q

A particular DNA sequence that differs by one or more mutations from homologous sequences

A

Haplotype

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4
Q

have the same sequence or relative position

A

homologous sequences

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5
Q

Unique genetic makeup of an individual, usually in relation to a specific gene

A

Genotype

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6
Q

1878-1958 geneticist -one of the first scientists to integrate genetics, development and evolution

A

Richard Goldschmidt

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7
Q

Proposed new species can arise by mutations (sudden changes in genetic makeup of an organism).

A

Mutationist Theories

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8
Q

Was the proponent of the idea of a “Hopeful Monster” where a sudden drastic change in the entire genome can sometimes create an entirely new higher taxon (any Linnaean rank above species)

A

Richard Goldschmidt

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9
Q

Mutationist Theories and Hopeful Monster were refuted by

A

modern synthesis of biological thought in 1930-1940’s

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10
Q

Even dramatic ________ are limited to alteration of pre-existing traits or developmental pathways.

A

mutations

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11
Q

“hopeful monster” idea of drastic new mutations is _________ valid

A

Not

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12
Q

Effects of mutations may be especially minimal in cases of _________ many loci affect the same trait.

A

polygeny

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13
Q

loci is the plural of _______ which is exact position for a gene on a chromosome

A

Locus

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14
Q

Are mutations random?

A

yes

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15
Q

Mutations are random in two areas:

A
  1. has no pre-determined “goal”, any nucleotide of the genome can have a mutation
  2. the environment does not induce advantageous mutations- this is Lamarckian-inheritance of acquired characteristics.
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16
Q

Speciation is driven by

A

Mutations

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17
Q

1809-1882
Differential survival due to natural selection
Heritable variation
Heritable adaptive variation is due to random mutations.

A

Charles Darwin

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18
Q

Black moths changed over time because only the ones with the gene to change color would survive being eaten by birds so this is

A

mutation driven speciation

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19
Q

The average human mutation rate is

A

0.000000048 per base pair/generation (very low)

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20
Q

A diploid genome has 6.6 x 10^9 bp so the average zygote has ________ new mutations

A

317

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21
Q

The average human zygote carries about _____mutations that are potentially harmful

A

7

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22
Q

Mutational event substitution, deletion, or insertion of a base pair

A

point mutation

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23
Q

chromosomal deletion, insertion, or rearrangement

A

chromosomal mutation

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24
Q

point mutations result in ______ _____ (changes function of gene) only if they occur in coding region of gene or regulation sequences

A

gene mutations

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25
Q

occur in somatic cells and only affect the individual in which the mutation arises.

A

somatic mutations

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26
Q

alter gametes and passed to the next generation

A

germ-line mutations

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27
Q

what does the acronym G&G stand for?

A

Germ and Gamete

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28
Q

Which type of mutation occurs at a higher rate?

A

transition mutations

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29
Q

mutation at one nucleotide-can result in synonymous or silent mutations (no effect on amino acid translation), or non synonymous mutations (change amino acid translation)

A

base pair substitution

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30
Q

all synonymous and SOME NON SYNONYMOUS mutations can result in NO effect on phenotype or major effects- this is a

A

neutral mutation

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31
Q

changes an amino acid from one to another in transition mutation

A

Missense mutation

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32
Q

Changes from an amino acid to a stop codon in a transversion mutation

A

Nonsense mutation

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33
Q

What are the stop codons?

A

UAA, UAG, UGA

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34
Q

changes from an amino acid to another amino acid with similar chemical properties; transition mutation

A

neutral mutation

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35
Q

changes in codon such that the same amino acid is specified in a transition mutation

A

silent mutation

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36
Q

a type of mussense mutation in that a different amino acid results, but the function of the amino acid doesn’t change

A

Neutral Mutations

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37
Q

do not result in an amino acid change-remember wobble

A

silent mutations

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38
Q

a mutation at a different site from original mutation that compensates for the negative effects of the original mutation

A

suppressor mutation

39
Q

different chemical states of nitrogenous bases

A

Tautomers

40
Q

Normal state of nitrogenous bases.

A

Keto form

41
Q

Hydroxyl group (OH) affixed to a carbon with a double bond

A

Enol Form

42
Q

Double bond migrates and moves position of hydrogen bonds

A

Imino Form

43
Q

These forms are rare-but they can cause unusual base pairing, leading to mutations

A

Enol and Imino

44
Q

How do suppressor mutations work?

A
  1. mutation in DNA makes a stop codon in mRNA transcript.
  2. Suppressor mutation in anticodon of tRNA allows it to bind to stop codon.
  3. Suppressor mutation allow translation to continue, but with one different AA
45
Q

How do tautomers lead to mutation?

A
  1. parental DNA
  2. DNA replicaiton
  3. point mutation occurs with wobble
  4. mismatched base pairs replicate in mRNA
  5. going back to DNA the base pair is mismatched and it becomes a mutant type DNA.
46
Q

What types of spontaneous mutations occur without any special anent?

A
  • DNA replication errors
    • Base substitution: tautomers→specific transitions.
    • Deletions/additions: looping out→ frame shifts in genes.
  • Molecular Changes
    • Depurination: (1 purine removed): → polymerase stalls at missing base.
    • Deanimation (amino group removed from base): C→U, CG→TA transitions.
47
Q

What type of mutations occur when induced: Radiation & chemicals

A
  • Ionizing and UV light→point mutations+thymine dimers
  • Base analogs: high frequency tautomers→specific transitions
  • Base modifiers→specific transitions
  • intercalators→deletions/additions→frameshift in genes.
  • Carcinogens: mutagens that cause cancer
48
Q

Why does UV light cause mutations?

A

because DNA absorbs light in the ultraviolet range.

49
Q

Ultraviolet light commonly causes _______ ______ (T’T) to form , which disrupts A-T pairing, causes a bulge in DNA, disrupts DNA replication at bulge, and can lead to cell death (skin cancer)

A

Thymine Dimers

50
Q

Effects of ionizing radiation is ________

A

cumulative-gets worse over time.

51
Q

what are Intercalating agents?

A

agents used to insert or delete a nucleotide in in some template DNA strand.

52
Q

What is used to stain DNA during electrophoresis

A

Ethidium bromide

53
Q

_________ inserts into DNA multiple times, and glows under UV light

A

Ethidium

54
Q

what is the result of an addition intercalating agent within a protein coding?

A

a frame shift mutatioin

55
Q

what is the result of an intercalating deletion within a protein coding gene?

A

a new dna strand is replicated and the nucleotide if removed.

56
Q

removes mutated base and replaces it with the correct one

A

base-excision repair

57
Q

Base Excision repair

A
  1. Uracil-DNA glycosylase-cleaves bond between sugar and base.
  2. Endonulease cleavage-cuts away baseless sugar.
  3. DNA Polymerase activity-inserts correct base.
  4. ligase activity- bonds new base to others in DNA strand.
58
Q

In Nucleotide excision repair what can correct thymine dimers and other serious DNA distortions.

A

proteins

59
Q

point mutations are divided into two classes :

A
  1. forward mutation: changes a wildtype gene to a mutant genel.
  2. reverse mutation aka reversion or back mutation-changes a mutant gene at the same site so that it functions in a completely wild-type or nearly wild-type way.
60
Q

the creation of mutations, can occur spontaneously or can be induced.

A

mutagenesis.

61
Q

naturally occurring mutations

A

spontaneous mutation

62
Q

occur when an organism is exposed either deliberately or accidentally to a physical or chemical agent, known as a mutagen.

A

induced mutations.

63
Q

this is the loss of a purine from the DNA when the bond hydrolyzes between the base and deoxyribose sugar, resulting in an apurinic site.

A

Depurination

64
Q

This is the removal of an AMINO GROUP from a base.

A

Deamination

65
Q

What is considered the “hot spot” for mutations

A

5 methyl Cytosine

66
Q

UV light can cause mutations between two pyrimidines which are _______ and will cause them to bond to each other making them ______ ______

A

thymine, thymine dimers.

67
Q

1930’s for the discovery of the production of mutations my means of x-ray irradiation

A

Herman joseph Muller

68
Q

being able to mutate a gene at specific positions in the base-pair sequence is ______

A

site-specific mutagenesis

69
Q

Benzpyrene, a polycyclic aromatic hydrocarbon found in cigarette smoke, coal tar, automobile exhaust fumes, and charbroiled food, is nonmutagenic

A

but its metabolite, benzpyrene diol epoxide, which is both a mutagen and a carcinogen, can induce cancer.

70
Q

mutations = what?

A

DNA damage - DNA repair

71
Q

There are two general categories of repair systems based on the way they function which are

A

Direct reversal repair system: which corrects damaged areas by reversing the damage.
2. Excision repair system -which cuts out a damaged area and then repair the gap by new DNA synthesis.

72
Q

a repair glycosylase enzyme removes the damaged base from the DNA by cleaving the bond between the and the deoxyribose sugar.

A

base excision repair

73
Q

Many mismatched base pairs left after DNA replication and missed by proofreading can be corrected by

A

Methyl-directed mismatch repair

74
Q

This system recognizes mismatched base pairs, excies the incorrect bases, and then carries out repair synthesis

A

methyl-directed mismatch repair

75
Q

what is the last resort for fixing a mutation in the DNA

A

translesion DNA synthesis

76
Q

individuals with a lethal affliction to photosensitivity, and portions of their skin have been exposed to light show intense pigmentation, freckling, and warty growths that can become malignant is known as

A

xeroderma pigmentosum

77
Q

xeroderma pigmentosum is caused by homozygosity for a recessive mutation ______ ______

A

repair gene.

78
Q

which polymerase’s repair DNA in methyl-mismatch repair

A

DNA polymerase III and ligase

79
Q

transposable elements fall into two general classes based on how they move from location to location in the genome they are

A
  1. found in both prokaryotes and eukaryotes-moves as a DNA segment.
  2. found only in eukaryotes-are related to retroviruses and move via an RNA. (first an RNA copy of the element is synthesized; then a DNA copy of that RNA is made, and it integrates at a new site in the genome)
80
Q

who allowed kids with xeroderma pigmentosum into a national park

A

Walt Disney

81
Q

Barbara McClintock 1902-1992

A

Was Born in Hartford CT, an accomplished pianist, and painter and Thomas Henry McClintock a physician was her husband, Went to Cornell Worked with Lowell Randolph, was famous for her work with maize. the corn purple

82
Q

contains genes for the insertion of the DNA segment into the chromosome and the mobilization of the element to other locations on the chromosome.

A

transposons

83
Q

is the simplest transposable element found in bacteria ______

A

IS (insertion sequence)

84
Q

The transposition of an IS element requires an enzyme encoded by the IS element called ______

A

transposase

85
Q

There are two types of transposons which are

A
  1. Composite transposons

2. NonComposite transposons

86
Q

was awarded the nobel prize in 1983 in physiology or medicine and her discovery of mobile genetics

A

Barbara McMclintock

87
Q

worked with corn maize in the 1940’s and 1950’s

A

Barbara McClintock

88
Q

Hypothesized the existence of “controlling elements”

A

Barbara McClintock

89
Q

TE that functions independently is called

A

autonomous element

90
Q

TE that does not function independently but needs help to activate it

A

non-autonomous element

91
Q

Both prokaryote and eukaryote have TE’s that encode proteins that allow them to “jump” to another part of the genome or copy and then insert it elsewhere

A

non-homologous recombinations

92
Q

Only ______ have a second type of TE that uses reverse transcriptase to make ______ copies of _______ transcripts and insert into the genome.

A

eukaryotes, DNA, mRNA

93
Q

TE’s can jump any place randomly into the genome with the following effects:

A
  1. if inserted into a coding gene can destroy genes function (null mutation)
  2. if inserted in a non-coding region (majority) has a neutral effect.
  3. if inserted into a regulatory region can enhance or destroy it.
  4. can cause chromosome mutation-inserstion, deletion, or breakage.
94
Q

why are TE’s in general rare?

A

because frequent TE activity would likely kill the cell

genetics (10 decks)

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