Chromosomal Disorders ✅

Question 1

Where are chromosomes found?

Answer 1

In the nucleus of every nucleated cell

Question 2

What does each chromosome consist of?

Answer 2

DNA that is tightly coiled around proteins known as histones that support its structure

Question 3

What does much of what we know about chromosomes come from?

Answer 3

Observations during cell division

Question 4

Why does much of what we know about chromosomes come from observations during cell division?

Answer 4

Because the DNA becomes more tightly coiled, and is thus visible under a microscope

Question 5

How many chromosomes do humans normally have?

Answer 5

46

Question 6

What are the 46 chromosomes made up of?

Answer 6

22 pairs of numbered chromosomes (autosomes) and one pair of sex chromosomes (XX or XY)

Question 7

What is a centromere?

Answer 7

A constricted region of each chromosome

Question 8

What are the regions on either side of the centromere known as?

Answer 8

The chromosomes ‘arms’

Question 9

What is the shorter arm of the chromosome known as?

Answer 9

The p arm

Question 10

What is the longer arm of the chromosome known as?

Answer 10

The q arm

Question 11

What are the ends of the chromosomes known as?

Answer 11

Telomeres

Question 12

What is each chromosome arm divided into?

Answer 12

Regions, or bands

Question 13

How can the bands of chromosomes be seen?

Answer 13

Microscopically with special stains

Question 14

How are the bands of chromosomes labelled?

Answer 14

By counting out from the centromere, with p1 and q1 being the closest to the centromere

Question 15

What is found within the bands of the chromosomes?

Answer 15

Sub-bands

Question 16

How are sub-bands numbered?

Answer 16

Outwards from the centromere

Question 17

What can chromosomal abnormalities be classified into?

Answer 17

• Numerical abnormalities

- Structural abnormalities

Question 18

What do numerical chromosome abnormalities involve?

Answer 18

Missing or extra whole chromosome from a pair

Question 19

What is it called when a whole chromosome is missing?

Answer 19

Monosomy

Question 20

What is it called when there are extra chromosome?

Answer 20

Trisomy or tetrasomy

Question 21

Give 2 examples of disorders cause by numerical abnormalities of chromosomes

Answer 21

• Turner’s syndrome

- Down’s syndrome

Question 22

What is the chromosomal abnormality in Turner’s syndrome?

Answer 22

Monosomy X

Question 23

What is the chromosomal abnormality in Down’s syndrome?

Answer 23

Trisomy 21

Question 24

What forms can structural abnormalities of chromosomes take?

Answer 24

• Translocation
• Insertion
• Deletion
• Inversion
• Duplication
• Ring

Question 25

What is a translocation?

Answer 25

A portion of one chromosome is transferred to another chromosome

Question 26

What is an insertion?

Answer 26

A segment of a chromosome is inserted into another position on a chromosome

Question 27

What is a deletion?

Answer 27

A portion of the chromosome is missing

Question 28

What is an inversion?

Answer 28

A portion of chromosome has broken off, turned upside down, and reattached

Question 29

What is a duplication?

Answer 29

A portion of the chromosome is duplicated, meaning there is extra genetic material

Question 30

What is a ring chromosomal abnormality?

Answer 30

A chromosome has formed a circle

Question 31

Does a ring chromosomal abnormality have a loss of genetic material?

Answer 31

Can occur with or without