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2014 Genetics Topic 1:CM > L10 > Flashcards

L10 Flashcards

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1
Q

What are the effects of translocation on chromosome behaviour

A

can affect gene dosage, the fertility of heterozygotes and the expression of genes

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2
Q

what is the difference between euploids and aneuploids

A

euploids: contain multiple copies of whole chromosome sets whislt…
aneuploids: contain multiple copies of one or more individual chromosomes

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3
Q

What are the two groups which euploids can be divided into

A

autopolyploids and allopolyploids

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4
Q

what are autopolyploids

A

have multiple copies of the same genome and consequently have different, though highly characteristic patterns of meiotic chromosome pairing

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5
Q

what are alloployploids

A

contain multiple copies of different genomes which are derived from different species; important in selective breeding in many crop plants

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6
Q

true or false, aneuploids are much less common than euploids

A

true

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7
Q

what is translocation

A

it involves the movement of genetic material between non homologous chromosomes of within the same chromosome (less common)

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8
Q

what are the two types of translocation

A

reciprocal and non reciprocal

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9
Q

true or false, translocation changes chomosome structure

A

true

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10
Q

true or false, translocation can physically link genes that were previously located on different chromosomes

A

true

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11
Q

What is Neurofibromatosis

A

is a genetic disease characterised by numerous fibrous tumours of the skin and nervous system; this was mapped by using translocation break points

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12
Q

true or false, translocations can result in abnormal meiotic configurations

A

true

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13
Q

why does a cross like configuration form between homologous chromosomes in prophase 1

A

this is because the chromosomes have parts of the to other homolog with it due to reciprocal translocation

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14
Q

why do chimps, gorillas and orangutans have 48 chromosomes whereas humans have 46 chromosomes

A

due to a translocation loss of a chromosome in humans

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15
Q

what is a numerical mutation

A

changes in chromosome number that can have a major impact on on the development and have an impact on the evolution of most organisms

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16
Q

true or false, human chromosome 2 contains a Robertsonian translocation that is not present in chimps, apes and orangutans

A

true

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17
Q

true or false, is a diploid a type of euploid

A

true, AA BB CC two of each

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18
Q

what are the two classifications of chromosome number

A

euploidy and aneuploidy

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19
Q

What is polyploidy

A

polyploidy are organisms that have more than two sets of chromosomes

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20
Q

true or false, polyploidy is very common in plants but rarer in animals

A

true

21
Q

true or false, polyploidy is one of the major mechanisms by which new plant species have evolved

A

true

22
Q

true or false, in polyploidy there is often a correlation between the number of copies of the chromosome set and the size of the organism

A

true

23
Q

is there a correlation in plants, the cell volume is correlated with nuclear volume and the genome size

A

true

24
Q

what are the two groups that polyploidy is divided into

A

allopolyploids and autopolyploids

25
Q

what is an autopolyploid

A

has multiple chromosome sets from one species

26
Q

what is an allopolyploid

A

have multiple sets from two or more species

27
Q

true or false, autopolyploids 3n can arise naturally when meiosis fails and diploid gametes are produced

A

true

28
Q

how are triploids 3n produces

A

by crossing over 4n and 2n

29
Q

true or false, triploids are characteristically sterile because of unpaired chromosomes at meiosis

A

true

30
Q

true or false, polyploids can be made by treating plants with colchicine, a drug that inhibits spindle formation

A

true

31
Q

what is an allopolyploid

A

a plant that is a hybrid between two or more species; arise as a result of hybridization between two closely related species with subsequent chromosome doubling

32
Q

what is aneuploidy

A

the change in the number of individual chromosomes

33
Q

how can aneuploidy arise (3)

A
  • a chromosome may be lost in the course of mitosis or meiosis if for example its centromere is deleted
  • small chromosomes generated by translocations may be lost in mitosis or meiosis
  • aneuploid gametes may arise through non disjunction, the failure of homologous chromsomes or sister chromatids separating in mitosis or meiosis
34
Q

what is monosomic aneuploid

A

2n-1; A BB CC(eg)

35
Q

trisomic

A

2n +1

36
Q

nullisomy

A

2n-2

37
Q

tetrasomy

A

2n+2

38
Q

true or false, non disjunction is the most common cause of aneuploidy in both meiosis and mitosis

A

true

39
Q

true or false, meiotic non disjunction is more common

A

true; at meiosis 1 is the most common

40
Q

true or false, crossing over is necessary for normal chromosome pairing and with out it non disjunction at meiosis 1 increases

A

true

41
Q

compare non disjunction in mitosis and meiosis

A
  • Mitotic non disjunction can occur during development and result in sections of the body being aneuploid whilst in meiotic non disjunction the gametes are affected leading to the whole organism being aneuploid
42
Q

in meiosis where can non disjunction occur

A

chromosomes may fail to separate at either the first or second meiotic division

43
Q

true or false, aneuploidy usually alters the phenotype dramatically

A

true

44
Q

true or false, aneuploidy alters the dosage of some but not all genes (all genes located on that chromosome will be affected), as a result aneuploidy disrupts the relative concentrations of gene products and thereby interferes with normal development

A

true

45
Q

why is it less lethal when aneuploid occurs in sex chromosomes

A

for example the extra X chromosome is inactivated and the Y chromosome carries a few genes

46
Q

what is the most common human autosomal aneuploidy

A

Down Syndrome; trisomy 21

47
Q

true or false, people with down syndrome carry 3 copies of chromosome 21 ; primary down syndrome

A

true

48
Q

true or false, about 75% of the non disjunction even are maternal in origin and most arising in meiosis 1

A

true

49
Q

what is familial down syndrome

A

due to the translocation of genes between chromosome 21 and 14; approx. 4% of people

2014 Genetics Topic 1:CM (11 decks)

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