L10

Question 1

What are the effects of translocation on chromosome behaviour

Answer 1

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

Question 2

what is the difference between euploids and aneuploids

Answer 2

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

Question 3

What are the two groups which euploids can be divided into

Answer 3

autopolyploids and allopolyploids

Question 4

what are autopolyploids

Answer 4

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

Question 5

what are alloployploids

Answer 5

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

Question 6

true or false, aneuploids are much less common than euploids

Answer 6

true

Question 7

what is translocation

Answer 7

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

Question 8

what are the two types of translocation

Answer 8

reciprocal and non reciprocal

Question 9

true or false, translocation changes chomosome structure

Answer 9

true

Question 10

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

Answer 10

true

Question 11

What is Neurofibromatosis

Answer 11

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

Question 12

true or false, translocations can result in abnormal meiotic configurations

Answer 12

true

Question 13

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

Answer 13

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

Question 14

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

Answer 14

due to a translocation loss of a chromosome in humans

Question 15

what is a numerical mutation

Answer 15

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

Question 16

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

Answer 16

true

Question 17

true or false, is a diploid a type of euploid

Answer 17

true, AA BB CC two of each

Question 18

what are the two classifications of chromosome number

Answer 18

euploidy and aneuploidy

Question 19

What is polyploidy

Answer 19

polyploidy are organisms that have more than two sets of chromosomes

Question 20

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

Answer 20

true

Question 21

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

Answer 21

true

Question 22

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

Answer 22

true

Question 23

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

Answer 23

true

Question 24

what are the two groups that polyploidy is divided into

Answer 24

allopolyploids and autopolyploids

Question 25

what is an autopolyploid

Answer 25

has multiple chromosome sets from one species

Question 26

what is an allopolyploid

Answer 26

have multiple sets from two or more species

Question 27

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

Answer 27

true

Question 28

how are triploids 3n produces

Answer 28

by crossing over 4n and 2n

Question 29

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

Answer 29

true

Question 30

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

Answer 30

true

Question 31

what is an allopolyploid

Answer 31

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

Question 32

what is aneuploidy

Answer 32

the change in the number of individual chromosomes

Question 33

how can aneuploidy arise (3)

Answer 33

- 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

Question 34

what is monosomic aneuploid

Answer 34

2n-1; A BB CC(eg)

Question 35

trisomic

Answer 35

2n +1

Question 36

nullisomy

Answer 36

2n-2

Question 37

tetrasomy

Answer 37

2n+2

Question 38

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

Answer 38

true

Question 39

true or false, meiotic non disjunction is more common

Answer 39

true; at meiosis 1 is the most common

Question 40

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

Answer 40

true

Question 41

compare non disjunction in mitosis and meiosis

Answer 41

- 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

Question 42

in meiosis where can non disjunction occur

Answer 42

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

Question 43

true or false, aneuploidy usually alters the phenotype dramatically

Answer 43

true

Question 44

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

Answer 44

true

Question 45

why is it less lethal when aneuploid occurs in sex chromosomes

Answer 45

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

Question 46

what is the most common human autosomal aneuploidy

Answer 46

Down Syndrome; trisomy 21

Question 47

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

Answer 47

true

Question 48

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

Answer 48

true

Question 49

what is familial down syndrome

Answer 49

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