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BIO1334 - Genetics > Chromosome Variation and Sex Determination > Flashcards

Chromosome Variation and Sex Determination Flashcards

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Biology 101 flashcards
1
Q

What is the name for organisms with multiples of the basic chromosome set (genome)?

A

Euploid

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2
Q

What can vary among closely related species when euploid is involved?

A

Chromosome number

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3
Q

Give an example of euploid:

A

Chinese muntjac and Indian muntjac

Have different number of chromosomes but same number of genes

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4
Q

Define aberrant euploid:

A

Organisms that have more or fewer than the normal number of chromosome

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5
Q

Give examples of aberrant euploid:

A 
Polyploids
Triploid
Tetraploid
Pentaploids
Monoploids
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6
Q

Define polypoid:

A

have more than two chromosome sets

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7
Q

Define monoploid:

A

An individual of a typically diploid species that has only one set of chromosomes

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8
Q

Finish the sentence:

Eukaryotes haploid with…

A

one chromosome

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9
Q

Finish the sentence:

Eukaryotes diploid with…

A

two chromosomes

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10
Q

Are polyploids common in plants or mammals?

A

plants

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11
Q

Define aneuploid:

A

Individuals whose chrosumse number differ by one or a small number of chromosomes

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12
Q

Finish the sentence:

An aneuploid can have a chromosome number either greater or smaller than that of the…

A

wild type

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13
Q

Define trisomic:

A

2n + 1

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14
Q

Define monosomic:

A

2n - 1

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15
Q

Define nullisomic:

A

2n - 2

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16
Q

What can O stand for?

A

Absence chromosome

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17
Q

How can cells end up with two many or too few chromosomes?

A

Non-disjunction event at meiosis or mitosis

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18
Q

What does the risk of non-disfunction rise with?

A

Maternal age

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19
Q

Why do extra chromosomes affect phenotype so drastically?

A
  1. Gene balance - genes have evolved to function in a diploid genetic background and disrupting that background disrupts their function
  2. Expression of deleterious alleles on monosomic autosomes
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20
Q

What does duplication play an important role in?

A

Evolution of the genome

21
Q

How can chromosomes have extra pieces?

A

duplication

22
Q

How can chromosomes have missing pieces?

A

Deletion

23
Q

Finish the sentence:

Deletions can be small…

A

only covering a part of one gene

24
Q

Finish the sentence:

Deletions can be large, with chromosomes missing pieces large enough to be visualised on a …

A

karyotype

25
Q

What does FISH stand for?

A

Fluorescent in situ hybridisation

26
Q

What is copy number variation?

A

Chromosomes can have missing or extra pieces on one chromosome

27
Q

How can chromosomes have mixed-up pieces?

A

Inversion or translocation

28
Q

How do you create and inversion?

A

A segment of the chromosome is cut out, flipped and reinserted into the chromosome in the opposite orientation

29
Q

Are inversion balanced rearrangements?

A

Yes

30
Q

Why are inversions balance rearrangements?

A

They don’t gain or loss of genetic material

31
Q

When can inversion lead to duplication or deletion?

A

during meiosis

32
Q

What is translocation?

A

Rearrangement involving a part of one chromosome that has broken off and reattached to a different chromosome

33
Q

What sex determination system do mammals have?

A

XY

34
Q

Are males XY or XX?

A

XY

35
Q

Are females XY or XX?

A

XX

36
Q

Who discovered the Y chromosome?

A

Netti Stevens in 1905

37
Q

Describe the Y chromosome:

A
  • Determine maleness
  • Mostly repeated sequences
  • Very few genes
  • SRY maleness- determining gene
  • inherited father to son
38
Q

Describe the X chromosome:

A
  • Many genes: unrelated to sex-determination

- Males are homozygous for X-linked genes

39
Q

Examples of X-linked traits in humans:

A
  • Red-green colour vision deficiency
  • Haemophilia
  • Duchenne muscular dystrophy
40
Q

What prevents X-chromosome gene dosage differences having significant phenotypic effect?

A
  • Between XY males and XX females

- In cases of X-chromosome aneuploidy

41
Q

What is lynosiation?

A

In female mammals one X chromosome is epigenetically inactivated early in development

42
Q

Define reciprocal translocation:

A

Part of arms from one chromosome are switched with another

43
Q

Define robertonian translocation:

A

Arm of chromosomes fuse around a single centromere

44
Q

Finish the sentence:

X and Y chromosomes contain very little…

A

homology

45
Q

What do inactive X chromosomes look like?

A

Highly condensed ‘Barr’ body

46
Q

Are all species in the world XX for female and XY for male?

A

No, sometimes it is switched round

47
Q

How can X-linked recessive traits be deduced?

A
  • More males than females express trait
  • Skips a generation
  • If female expresses the characteristics, all male offspring will express trait
48
Q

In humans, there is a recessive, sex-linked allele for night-blindness (the inability to see in poor light). The wild-type allele, XN, results in typical night-vision. Curly hair is caused by a dominant allele of the gene W, while the recessive allele results in straight hair.
If a straight-haired, night-blind woman married a man with normal night-vision and curly hair, whose father had straight hair, what would be the probability that their first child would be a straight-haired, night-blind boy?

A) 0.00
B) 0.25
C) 0.50
D) 0.75

A

B

BIO1334 - Genetics (24 decks)

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