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BB10007 Genetics > ✅Transmission Genetics - Leslie Turner > Flashcards

✅Transmission Genetics - Leslie Turner Flashcards

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Biology 101 flashcards
1
Q

How do eubacteria replicate?

A

With a single origin of replication, high rate of reproduction, genes near ORI site and more highly expressed operon structure

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2
Q

What happens in G1 phase of mitosis?

A

The cell grows, mRNA and proteins synthesised

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3
Q

What happens in G0 phase of mitosis?

A

Cells may enter a non-dividing phase

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4
Q

What happens after the G1/S checkpoint of mitosis?

A

The cell is committed to dividing

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5
Q

What happens in S phase of mitosis?

A

DNA duplicates

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6
Q

What happens in G2 phase of mitosis?

A

The cell prepares for mitosis

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7
Q

What happens after the G2/M checkpoint of mitosis?

A

The cell can divide

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8
Q

What happens in prophase?

A

Chromosomes become visible after duplication, the mitotic spindle forms

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9
Q

What happens in prometaphase?

A

Disintegration of the nuclear membrane marks the start of prometaphase, and the spindle microtubules attach to chromatids

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10
Q

What happens in telophase?

A

Chromosomes arrive at spindle poles, the nuclear membrane re-forms and the chromosomes relax

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11
Q

What happens in anaphase?

A

Sister chromatids separate and move towards opposite poles

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12
Q

What happens in metaphase?

A

Chromosomes line up on the metaphase plate

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13
Q

In which stage of mitosis does the number of chromosomes per cell double?

A

8

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14
Q

What happens on meiosis I?

A

The separation of homologous chromosomes to produce two diploid daughter cells, crossing over takes place

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15
Q

What happens in meiosis II?

A

The separation of sister chromatids to produce four haploid daughter cells

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16
Q

What is the period between meiosis I and II called?

A

Interkinesis

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17
Q

What is crossing over?

A

The swapping of genetic material between homologous chromosomes

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18
Q

How does gametogensis and fertilisation lead to variation?

A

The sperm and the egg that fuse will contain different genes

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19
Q

What are the two classifications of mutations?

A

Somatic or germ line

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20
Q

What is a substitution?

A

One base is replaced by another

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21
Q

What is a transversion?

A

Changing a purine to a pyrimidine or vice versa

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22
Q

What is a transition?

A

Changing a purine for another purine or a pyrimidine for another pyrimidine

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23
Q

What is a point mutation?

A

A change to a single nucleotide in a DNA sequence that doesn’t change its length

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24
Q

What are expanding nucleotide repeats?

A

Mutations in which the number of copies of a set of nucleotides increases in number

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25
Q

What is a forward mutation?

A

One which changes the wild-type phenotype

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26
Q

What is a reverse mutation?

A

One which changes the phenotype back to the wild type

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27
Q

What is a missense mutation?

A

A substitution that results in a different amino acid in the protein

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28
Q

What is a nonsense mutation?

A

One which changes a sense codon (one that specifies an amino acid) into one that terminates translation

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29
Q

What is a silent mutation?

A

Changes a codon to a synonymous codon that specifies the same amino acid

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30
Q

What are incorporation errors and replication errors?

A

When a mismatched base has been incorporated into a newly synthesised nucleotide chain

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31
Q

What can cause a replication error?

A

Wobble

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32
Q

What causes wobble?

A

A base mismatch, eg thymine pairing with guanine

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33
Q

How does strand slippage occur?

A

When one nucleotide strand forms a small loop

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34
Q

What is unequal crossing over?

A

Caused by misaligned pairing, one DNA molecule has an insertion and the other has a deletion

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35
Q

What is depurination?

A

The loss of a purine through hydrolysis

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36
Q

What does depurination form?

A

An apurinic site

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37
Q

What is deamination?

A

The loss of a amino group, to form a different base eg C to U

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38
Q

What are base analogs?

A

Chemical structures similar to any of the bases

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39
Q

What is a pyrimidine dimer?

A

Two thymine bases block replication, can be induced with UV radiation

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40
Q

What are alkylating agents?

A

Chemicals that donate alkyl groups, EMS can add an ethyl group to guanine, producing a base like structure that pairs with guanine

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41
Q

What is hydroxylamine?

A

A specific base modifying mutagen that adds a hydroxyl group to cytosine

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42
Q

What is repeat expansion?

A

A special case of insertion, increase in the number of copies of nucleotides, during replication a hairpin occurs and loops back, pairing with itself and causing part of the template to be replicated twice

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43
Q

Why is there a male mutation bias?

A

Due to the continuous production of sperm compared to female eggs

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44
Q

What is a suppressor mutation?

A

Mutation that hides or suppresses the effect of another mutation

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45
Q

What is an intragenic suppressor mutation?

A

Occurs in the gene containing the gene being suppressed

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46
Q

What is an intergenic suppressor mutation?

A

Occurs in a gene other than the one bearing the original mutation

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47
Q

How can intragenic suppressors work?

A

It may change a second nucleotide in the same codon altered by the original mutation, producing a codon that specifies the same amino acid that is specified by the original, unmutated codon

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48
Q

How can intergenic suppressors work?

A

Sometimes work by changing the way that the mRNA is translated

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49
Q

What do chromosome mutations include?

A

Rearrangement, aneuploidy and polyploidy

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50
Q

What do rearrangements include?

A

Duplication, deletion, inversion, translocation

51
Q

What is duplication?

A

A segment of the chromosome is duplicated

52
Q

Where do most duplications occur?

A

Within the same chromosome (intra-chromosomal)

53
Q

What is a tandem duplication?

A

If duplications occur next to one another

54
Q

What is a reverse duplication?

A

Where the segment is flipped over

55
Q

What has to happen to the duplicated chromosome in prophase?

A

It has to loop out to align with the homologus chromosome

56
Q

How can duplication alter phenotypes?

A

It can alter gene dosage

57
Q

Why does chromosome duplication affect gene dosage?

A

It produces extra copies of some but not all genes

58
Q

What are segmental duplications?

A

Anything of more than 1000 base pairs, anything less is an indel

59
Q

What is an inversion?

A

A segment of the chromosome is turned 180 degrees

60
Q

What is a paracentric inversion?

A

When the centromere is unaffected

61
Q

What is a pericentric inversion?

A

When the centromere is affected

62
Q

How would abnormal gametes be formed by chromosome mutation?

A

In a heterozygote, a single crossover with a paracentric inversion would lead to abnormal gamete

63
Q

How do pericentric inversions affect gametes?

A

They have chromosomes of normal size but have too many or too few of some genes

64
Q

What is translocation?

A

Movement between non-homologous chromosomes

65
Q

What forms can translocations be?

A

Reciprocal, non-reciprocal or Robertsonian

66
Q

What is a reciprocal translocation?

A

When there is a two way exchange of segments between the chromosomes

67
Q

What is a Robertsonian translocation?

A

When the short arm of an acrocentric chromosome is exchanged with the long arm of another

68
Q

What is an acrocentric chromosome

A

Centromere at the end

69
Q

What is a metacentric chromosome?

A

Centromere in the middle

70
Q

What is aneuploidy?

A

The presence of an absnormal number of chromosomes in a cell

71
Q

What is nullisomy?

A

Loss of a homologous pair

72
Q

What is monosomy?

A

Loss of a single chromosome

73
Q

What is trisomy?

A

Gain of a single chromosome

74
Q

What is tetresomy?

A

Gain of a homologous pair

75
Q

What can cause aneuploidy?

A

Deletion of centromere, Robertsonian translocation, non-disjunction

76
Q

What is autoploidy?

A

All chromosomes are from a single species, can arise through non disjunction

77
Q

What is alloploidy?

A

Chromosomes are from two species, mostly arise from hybridisation between two species followed by chromosome doubling

78
Q

What is a monohybrid cross?

A

Cross between two parents that differ in a single characteristic

79
Q

What does gene conversion always lead to?

A

The death of gametes

80
Q

What does unequal crossing over lead to?

A

Duplication and deletion

81
Q

What does deamination of methylcytosine lead to?

A

C mutating to a T

82
Q

What was discovered by comparing human and chimp genomes?

A

The human chromosome 2 is the result of a Robertsonian translocation

83
Q

Which chromosome has the fewest trisomics?

A

1

84
Q

What is Mendel’s first law?

A

Each individual diploid organism possesses two alleles for any particular characteristic. These two alleles separate when gametes are formed and one alleles goes to each gamete

85
Q

What is the principle of dominance?

A

When two different alleles are present in a genotype, sometimes only the trait encoded by one of them, the ‘dominant’ allele is observed in the phenotype

86
Q

What is a backcross?

A

F1 is crossed to one parent

87
Q

What is a testcross?

A

Individual of unknown genotype crossed to known type

88
Q

What is a reciprocal cross?

A

Pair of crosses with phenotype of male and female parents reversed

89
Q

What revealed the law of independent assortment?

A

Dihybrid crosses

90
Q

What do segregation ratios depend on for two loci on the same chromosome?

A

The rate of crossing over between loci

91
Q

What reveals the effect of linkage?

A

Testcross

92
Q

If two genes are linked, what are all the progeny?

A

Non-recombinant, same as parental phenotypes

93
Q

How can the % recombinant progeny be calculated?

A

recombinant progeny/total x 100

94
Q

What is a linkage map?

A

The order and distance between loci on a chromosome

95
Q

What is distance between chromosomes measured in?

A

CentiMorgans, 1cM = 1% chance crossover

96
Q

What does non-Mendelian genetics include?

A

Mitochondria, chloroplasts, X/Y linked

97
Q

What is homoplasmy?

A

All organelles are genetically identical

98
Q

What is heteroplasmy?

A

Different cells in the same organism being genetically different

99
Q

What is position effect variation caused by?

A

Inversion mutation or transposons

100
Q

What are the characteristics of cytoplasmically inherited traits?

A

Present in males and females
Usually inherited from one parent
Reciprocal crossed give different results

101
Q

What do genetic maternal effects mean?

A

Offspring’s phenotype is determined by mother’s phenotype

102
Q

What is clonal inheritance?

A

Means the whole mtDNA has shared history

103
Q

What can be used as a clock to find the most recent common ancestor?

A

Mutation rate

104
Q

What is gene conversion?

A

The process by which one DNA sequence replaces a homologous sequence such that the sequences become identical

105
Q

When can gene conversion occur?

A

In meiosis, when crossing over is resolved differently

106
Q

What is DSBR?

A

Double strand break repair

107
Q

What is SDSA?

A

Synthesis dependent strand annealing

108
Q

What are homing endonucleases?

A

Stretches of DNA that code for sequences that both copy itself and cut the unoccupied allele at the correct insertion site

109
Q

What are B chromosomes?

A

Extra set of chromosomes, not stabily transmitted

110
Q

What is meiotic drive?

A

Gametes produced have unequal chance to fertilise

111
Q

What are nuclear non-Mendelian loci?

A

Selfish genetic elements which increase in frequency in populations quickly due to unfair inheritance

112
Q

What are monoecious individuals?

A

Ones that have both male and female reproductive structures

113
Q

What are didecious individuals?

A

Ones that have either male of female reproductive structures

114
Q

What is heterogametic sex?

A

Produces gametes with different types of sex chromosome, eg human male XY

115
Q

What is homogametic sex?

A

Produces gametes that all contain the same type of sex chromosome

116
Q

How does haplodiploidy work in bees?

A

An unfertilised egg becomes a male and a fertilised egg becomes a female

117
Q

What is genic sex determination?

A

Sex determining gene but no sex chromosomes

118
Q

How is the sex of reptiles often determined?

A

Based on temperature

119
Q

How is the sex of fish often determined?

A

They are born one sex and change based on social cues

120
Q

What is human sex determination based on?

A

The SRY gene on the Y chromosome

121
Q

What are sex limited traits

A

Genes present in both sexes but only expressed in one

122
Q

What are sex biased traits?

A

Genes present in both but expressed more in one sex

123
Q

What are sex linked traits?

A

Genes on sex chromosomes

124
Q

How did sex chromosomes differentiate?

A

A mutation of a gene on one chromosome causes maleness, and mutations at other genes affect male characteristics. Suppression of crossing over keep genes fro male traits linked to the male determining gene and over time, lack of crossing over leads to degeneration of the Y

BB10007 Genetics (3 decks)

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