Chromosomal Aberrations

Question 1

What is non-disjunction?

Answer 1

Failure of chromosomes to move to opposite poles

Question 2

When does non-disjunction occur?

Answer 2

Anaphase of Meiosis 1 and meiosis 2, oogenesis, spermatogenesis

Question 3

What happens if there is a complete absence of the x chromosome?

Answer 3

will die

Question 4

How is it possible for a sperm cell to carry 2 y chromosomes?

Answer 4

Because or non-disjunction at anaphase 2

Question 5

How do you write a karyotype?

Answer 5

Total no. of chromosomes, sex, what chromosome is extra eg. for down syndrome 47, XY, +21

Question 6

Breast enlargement in males

Answer 6

Gynecomastia

Question 7

A disorder where it occurs in 1 in 2000 newborn females, no masculinization, is sterile, and some with normal intelligence 45, XO

Answer 7

Turner syndrome

Question 8

Has a frequency of 1/1200, is taller than average, mostly with normal sexual development, increased risk of learning disabilities, delayed motor skills, hypotonia, behavioral and emotional difficulties

Answer 8

Metafemales or triplo x

Question 9

Has a frequency of 1/2000, and is named after Dr. Patricia Jacobs, characters include unusually tall, has tendency for subnormal intelligence, and tendency for personality disorder or aggressive behavior (has a karyotype of xyy)

Answer 9

Jacobs syndrome

Question 10

Who proposed to screen newborn infants for xyy karyotype in 1968 at the boston hospital for women?

Answer 10

Stanley walzer and park gerald

Question 11

What was the prison where Dr. Patricia Jacobs had karyotyped 315 males?

Answer 11

Scottish maximum security prison in 1965

Question 12

What are the types of aberrations?

Answer 12

Variation in chromosome number and structural aberrations

Question 13

The types of variation in chromosome number

Answer 13

Aneuploidy and euploidy

Question 14

This is the change in the number of one or a few chromosomes but not a complete set eg. 2n+1

Answer 14

Aneuploidy

Question 15

This is the change in the number of complete sets of chromosomes eg. 3n

Answer 15

Euploidy

Question 16

What are the types of structural aberrations?

Answer 16

Deletions, duplications, inversions, translocations, fragile sites

Question 17

How may aneuploidy arise?

Answer 17

1 loss of centromere leading to acentric chromosome, 2 loss of the small chromosome generated thru a robertsonian translocation, 3 non-disjunction

Question 18

What are the types of aneuploidy?

Answer 18

Nullisomy, monosomy, trisomy, tetrasomy

Question 19

This is the loss of both members of a homologous chromosome making it non-viable

Answer 19

Nullisomy

Question 20

What is an example of nullisomy?

Answer 20

Loss of sex chromosomes, or pair of autosomes

Question 21

What is monosomy?

Answer 21

Loss of a single chromosome eg. 2n-1 XO Turner’s syndrome

Question 22

This is the gain of a single chromosome eg. 2n+1, xxy, xxx, xyy

Answer 22

Trisomy

Question 23

What are examples of trisomy?

Answer 23

Sexual trisomy: Kleinfelter, metafemale, jacobs note: there are also autosomal trisomy

Question 24

What is 2n+1+1?

Answer 24

Double trisomy

Question 25

This is the gain of 2 homologous chromosomes eg. 2n+2, xxxx, xxxy

Answer 25

Tetrasomy

Question 26

What is 2n-1-1?

Answer 26

Double monosomy which is an aberration at 2 chromosome locations

Question 27

What are the types of autosomal trisomy?

Answer 27

Trisomy 21, trisomy 18, trisomy 13

Question 28

What is trisomy 21?

Answer 28

Down syndrome

Question 29

What is trisomy 18?

Answer 29

Edwards syndrome

Question 30

What is trisomy 13?

Answer 30

Patau syndrome

Question 31

Characterized by mental retardation, congenital heart defects, 1/100 risk of leukemia, short broad skull, cataracts, life expectancy is 30 yrs but 25% live up to 50 yrs also known as mongolism

Answer 31

Down syndrome

Question 32

What is the probability of getting child with down syndrome at the age of 20?

Answer 32

1/2000

Question 33

What is the probability of getting child with down syndrome at the age of 30?

Answer 33

1/900

Question 34

What is the probability of getting child with down syndrome at the age of 40?

Answer 34

1/100

Question 35

What is the probability of getting child with down syndrome at the age of 50?

Answer 35

1/12

Question 36

What are the characteristics of edward syndrome?

Answer 36

1/8000 live births, severely retarded, elfin appearance, receding lower jaw, low set ears, short neck, deformed teeth, clenched fingers, heart problems

Question 37

This usually affects females with a mortality of 80% at 2 yrs old

Answer 37

Edwards syndrome

Question 38

1/15000 live births, severe mental retardation, small head, sloping forehead, small eyes, cleft lip and palate, polydactyly

Answer 38

Patau syndrome

Question 39

Half of children die within the 1st month and 95% die by age 3

Answer 39

Patau syndrome

Question 40

Why does monosomy and trisomy not common for other autosomes?

Answer 40

Because deformation is so severe it leads to spontaneous abortion

Question 41

Why does euploidy occur?

Answer 41

Because of polyspermy

Question 42

This is common in plants where 40% occurs in flowering plants and about 70-80% occurs in grasses and thus is agriculturally important

Answer 42

Polyploidy

Question 43

All chromosome sets are from a single species

Answer 43

Autopolyploidy

Question 44

Even no. of polyploids have______ survival and fertility than odd no. of polyploids

Answer 44

Greater

Question 45

There is _______ fertility in genetically unbalanced daughter cells

Answer 45

Reduced

Question 46

This is when chromosome sets are from 2 different species

Answer 46

Allopolyploidy

Question 47

9A9B in f2 generation

Answer 47

Amphidiploid or allotetraploid

Question 48

What are the significance of polyploidy?

Answer 48

Increase in chromosome number causes increase in cell size, many polyploids have bigger flowers, fruits, leaves, and seeds or sometimes no seeds

Question 49

female horse x male donkey

Answer 49

Mule

Question 50

male horse x female donkey

Answer 50

Hinny