Chromsome Structure

Question 1

Where is DNA found in animal cells, plant cells and prokaryotic cells?

Answer 1

Animal - Nucleus and mitochondria
Plant- nucleus, mitochondria and chloroplasts
Prokaryote - cytoplasm and plasmids

Question 2

What is chromatin?

Answer 2

DNA in chromosomes that is complexed with protein

Question 3

What are the 2 types of interphase chromatin?

Answer 3

1. Euchromatin - DNA that is active (being expressed as protein
2. Heterochromatin - Mostly inactive DNA - CONSTITUTIVE AND FACULATIVE

Question 4

What are the 2 types of Heterochromatin?

Answer 4

-Constitutive - never expressed, near centromere mostly repetitive DNA
-Faculative - sometimes expressed

Question 5

Which is the short and long arm of the chromosome?

Answer 5

P is the short arm and Q is the long arm

Question 6

What phase are chromosomes in when being looked at?

Answer 6

Metaphase

Question 7

What are sister chromatids?

Answer 7

The identical double structures the chromosome has been replicated into during dividing

Question 8

What are the proteins called that keeps the DNA compact?

Answer 8

Histones

Question 9

What does Metacentric mean?

Answer 9

The centromere is close to the midpointä

Question 10

What does Submetacentric mean?

Answer 10

The centromere is removed from the midpoint so a short arm (p arm) and long arm (q arm) can be seen

Question 11

What does Acrocentric mean?

Answer 11

The centromere is near the end and the short arm only can be seen - sometimes has satellites on end of arm

Question 12

What does Telocentric mean?

Answer 12

The centromere is at one end and only one arm can be seen

Question 13

What is the complete set of diploid chromosomes called?

Answer 13

Karyotype

Question 14

What treatments can be used to aid oin distinguishing between chromosomes?

Answer 14

Giemsha staining - reveals G bonding patterns

Question 15

What is Aneuploidy?

Answer 15

When an individual is missing either a chromosome from a pair (monosomy) or has more than 2 chromosomes of a pair (trisomy)

Question 16

Why might Aneuploidy occur?

Answer 16

Due to abnormalities in meiosis

Question 17

What are examples of Aneuploidy?

Answer 17

Down Syndrome Trisomy 21, Trisomy 18 Edwards Syndrome

Question 18

What is Polyploidy?

Answer 18

Occurs in cells when there are more than 2 sets of chromosomes

Question 19

How does Polyploidy occur?

Answer 19

Due to abnormal cell division during mataphase in meiosis

Question 20

What are deletions?

Answer 20

A portion of the chromosome is missing or deleted. Terminal or interstitial

Question 21

What are the effects of Deletions?

Answer 21

-Insufficient gene products
-Unmansking of mutant alleles on normal chromosomes
–Example; Cri de chat

Question 22

What are Duplications?

Answer 22

A portion of the chromosome is duplicated resulting in extra genetic material

Question 23

What are Inversions?

Answer 23

A portion of the chromosome has broken off, turned upside down and reattached, therefore the genetic material is inverted
-Pericentric - both arms
-Paracentric - one arm

Question 24

What are Rings

Answer 24

A portion of a chromosome has broken off and formed a circle or ring - can happen with or without loss in genetic material - epilepsy and mental retardation

Question 25

What are Translocations?

Answer 25

When a portion of one chromosome is transferred to another chromosome
-Reciprocal translocation
-Robertsonian translocation

Question 26

What is reciprocal translocation?

Answer 26

When segments from 2 different chromosomes have been exchanged

Question 27

What is Robertsonian translocation?

Answer 27

When an entire chromosome has attached to anotjer at the centromere

Question 28

What chromosomes do Robertsonian translocation only occur at and why

Answer 28

Chromosomes 13,14,15,21 and 22 as these are telecentric