genetics lecture 9

Question 1

what polyploidy

Answer 1

Three or more sets of the same chromosomes

Question 2

what causes polyploidy

Answer 2

when meiosis goes wrong

Question 3

what is polyploidy common in/

Answer 3

common in plants but rare in most animals, it causes sterility in plants and is used by breeders to produce seedless fruits.

Question 4

Aneuploidy

Answer 4

An increase or decrease of the number of individual chromosomes

Question 5

Nullisomy

Answer 5

The loss of both numbers of homologous pair of chromosomes.

Question 6

Monosomy

Answer 6

The loss of a single chromosome

Question 7

Trisomy

Answer 7

The gain of a single chromosome

Question 8

Tetrasomy

Answer 8

The gain of 2 homologous chromosomes

Question 9

How does aneuploidy occur?

Answer 9

Caused by two homologous chromosomes not separating during meiosis. This is called a non-disjunctional event.

One daughter cell has both chromosomes, while the other has none when fertilised, either 2n +1 = trisomy or 2n-1 = monosomy.

Question 10

what causes down syndrome

Answer 10

Down’s syndrome is usually caused by trisomy of chromosome 21.

Question 11

Klinefelter’s syndrome male

Answer 11

xxx

Question 12

Trisomy X female

Answer 12

XXX

Question 13

Jacob’s syndrome male

Answer 13

XYY

Question 14

Turner syndrome female

Answer 14

XO

Question 15

Detection of Barr Bodies

Answer 15

to determine sex chromosome abnormalities

Question 16

what should a female barr body have normal

Answer 16

A normal female (XX) should have a single Barr body whereas a female with three X chromosomes will have 2 Barr bodies.

Question 17

what causes turner sydrome

Answer 17

Usually caused by a non-disjunction event
A pair of sex chromosomes does not separate during formation of either egg or sperm

Question 18

what happens when an abnoraml egg unites with a nomral sperm to form embryo (turner sydnrome)

Answer 18

It ends up lacking a sex chromosome i.e. X instead of XX, hence the offspring is X0

Question 19

what are the results of jacobs syndrome

Answer 19

extra Y chromosome
slightly taller than average
more active
normal intelligence, slight learning disabilities
delayed emotional immaturity
normal sexual development

Question 20

Trisomy X (metafemale) outcome

Answer 20

Tall stature
Small head (microcephaly)
Vertical skin folds that may cover the inner corners of your eyes
Weak muscle tone