Numerical Chromosomal Abnormalities

Question 1

What causes turners syndrome?

Answer 1

Females with only one X chromosome

Question 2

What causes pataus syndrome?

Answer 2

Trisomy 13

Question 3

What causes edwards syndrome?

Answer 3

Trisomy 18

Question 4

What is polyploid?

Answer 4

Multiple of the haploid number

Question 5

What is aneuploid?

Answer 5

Chromosome number which is not an exact multiple of haploid number due to an extra or missing chromosome

Question 6

What is a bivalent structure?

Answer 6

Two chromosomes on top of each other

Question 7

What is the bivalent structure joined by?

Answer 7

Synpatonemal complex (protein structure)

Question 8

What is crossing over?

Answer 8

Reciprocal breaking and re-joining of the homologous chromosomes in meiosis

Question 9

What does crossing over result in?

Answer 9

Exchange of chromosomal segments and new allele combinations

Question 10

What is a non-recombinant chromosome?

Answer 10

The one thats the same as the parent strand

Question 11

What are the most common aneuploidies?

Answer 11

13, 18 and 21

Question 12

What is triple X syndrome and how many chromosomes does it result in?

Answer 12

Three X chromosomes in a female - 47 chromosomes

Question 13

What is kleinfelter syndrome and how many chromosomes does it result in?

Answer 13

XXY in males - 47 chromosomes

Question 14

When are sex chromosome aneuploidies diagnosed?

Answer 14

At puberty or when they cause fertility problems

Question 15

What is mitotic non-disjunction?

Answer 15

When the majority of cells are 2n but some are 2n+1

Question 16

Why are there no 2n-1 cells when mitotic non-disjunction takes place?

Answer 16

They die out bc they dont have the full set of chromosomes

Question 17

What is mosaicism?

Answer 17

The presence of two or more genetically different cell lines derived from a single zygote

Question 18

What are the two ways you can get mosaicism?

Answer 18

Starting from normal cell that non-disjunction happens in

Or

Start with a trisomic cell -> trisomic rescue

Question 19

What happens in trisomic rescue?

Answer 19

Cell recognises that it has the wrong number of chromosomes and throws one out at random

Question 20

How does full monosomy arise?

Answer 20

Nondisjunction