Abnormal Meiosis

Question 1

What does abnormal meiosis result in?

Answer 1

• chromosome abnormalities

Question 2

What is a way in which abnormal meiosis can occur?

Answer 2

• chromosome non-disjunction

Question 3

When does chromosome non-disjunction occur?

Answer 3

• when chromosomes fail to separate correctly during meiosis

Question 4

What happens if chromosome non-disjunction occurs in the sex chromosomes?

Answer 4

• fertilisation involving one of these abnormal gametes will result in a zygote with either an extra or missing chromosome
• a condition known as aneuploidy

Question 5

What is aneuploidy?

Answer 5

• a condition wherein chromosomes fail to separate correctly during meiosis
• resulting in a zygote with either an extra or a missing chromosome

Question 6

What is a diagnosis?

Answer 6

• the identification of the nature of an event

Question 7

What is a prognosis?

Answer 7

• the prediction of how the event will develop

Question 8

What are some examples of aneuploidy?

Answer 8

• klinefelter’s syndrome
• down syndrome

Question 9

When does klinefelter’s syndrome occur?

Answer 9

• when a boy is born with an extra copy of the x chromosome
• when the sex chromosomes in the egg (or very rarely in the sperm) split unevenly

Question 10

What are some of the possible symptoms of klinefelter’s syndrome?

Answer 10

• sparse body hair
• enlarged breasts
• small testicles and penis
• not very deep voices
• infertility

Question 11

When does down syndrome occur?

Answer 11

• when children are born with an extra copy of chromosome number 21

Question 12

How does down syndrome come about?

Answer 12

• during oogenesis, the 2 number 21 chromosomes do not separate properly during anaphase 1
• both go into 1 daughter cell instead of 1 into each of the 2 cells formed

Question 13

What are some down syndrome characteristics?

Answer 13

• varying degrees of mental retardation
• distinctive flattened facial features with slanting eyes
• often heart defects