Chromosomal Basis of Inheritance

Question 1

when are chromosomes most visible?

Answer 1

Metaphase

Question 2

Karyotype?

Answer 2

the number and appearance of chromosomes

Question 3

Where on the chromosome is the telomere?

Answer 3

the ends

Question 4

What can increase the risk of errors at gametogenesis?

Answer 4

Increased maternal age can increase the risk of aneuploidy.

*aneuploidy = trisomy or monosomy

Question 5

What are the stages of Meiosis 1 ?

Answer 5

1) Prophase (chromosomes condense)
2) Metaphse ( chiasmata - chromosomes line up)
3) Anaphase (chromosmes separate)
4) Telophase
(cell begins to divide

Question 6

What is Non-disjunction?

Answer 6

failure of the chromosomes / chromatids to separate

Question 7

What genetic condition is characterised by a single palmar crease, sandal gap between 1st and 2nd toes and general flat face?

Answer 7

Trisomy 21

Question 8

What is edwards syndrome?

Answer 8

Trisom 18

congenital heart disease, cleft lip / palate

Question 9

trisomy 18

Answer 9

Edwards syndrome

Question 10

Patau Syndrome

Answer 10

Trisomy 13

• polydactyly
• heart defect
• abnormal genitalia
• cleft lip

Question 11

Trisomy 13

Answer 11

Patau Syndrome

Question 12

Turners syndrome

Answer 12

45,X

• Loss of ovarian function
• No puberty
• Infertility

Question 13

Klinefelters syndrome

Answer 13

47,XXY

Question 14

45,X

Answer 14

Turners syndrome

Question 15

47,XXY

Answer 15

Klinefelters syndrome
-infertility
-

Question 16

When does gain of a whole chromosome set occur?

Answer 16

Fertilisation

Question 17

What is reciprocal translocation?

Answer 17

exchange of material between non homologous chromosomes

Question 18

What is robertsonian translocation?

Answer 18

translocation of a whole arm on chromosomes with an acrocentric centromere (chromosomes 13, 14, 15, 21, 22)

Question 19

What are the 2 types of Inversions that can happen?

Answer 19

1) Pericentric
(opposite arm /side of centromere)

2) Paracentric
(same arm/side of centromere)

Question 20

What are the commonest types of unbalanced rearrangements?

Answer 20

deletions and duplications

Question 21

What are the types of deletions?

Answer 21

Terminal Deletion

Interstitial deletion