Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

USMLE Biochemistry > Meiosis > Flashcards

Meiosis Flashcards

1
Q

What happens in the process of Meiosis I?

A

Diploid cell become haploid (reductive division)
- Homologous chromosomes become separated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Name all cells involved in spermatogenesis?

A
  • Spermatogonium
  • Primary spermatocyte
  • Secondary spermatocyte
  • Spermatid
  • Spermatozoa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What do spermatagonium undertake to become primary spermatocytes?

A

Mitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What do primary spermatocytes undergo to become secondary spermatocytes?

A

Meiosis I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What do secondary spermatocytes undergo to become spermatids?

A

Meiosis II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What so spermatids undergo to become spermatozoa?

A

Spermiogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What stage of meiosis are primary oocytes arrested in until puberty?

A

Prophase of meiosis I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

After puberty what stage of meiosis are oocytes arrested in until fertilisation?

A

Metaphase of meiosis II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does the term aneuploidy mean?

A

An abnormal chromosome number (monosomy or trisomy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is disomy?

A

2 copies of a chromosome (normal)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is monosomy?

A

1 copy of chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is trisomy?

A

3 copies of chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is meiotic nondisjunction?

A

Failure of chromosome pairs to separate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

When can meiotic nondisjunction occur?

A

Either in meiosis I or II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

If meiotic nondisjunction occurs in meiosis I how many chromosomes will the daughter cells have by Meiosis II?

A

There will be 2 diploid daughter cells (with mixture of maternal and paternal genes) and 2 cells w/o chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Give an example of a syndrome with monosomy?

A

Turner syndrome (45X)

17
Q

What trisomys are compatible with life?

A
  • Trisomy 21: Down syndrome
  • Trisomy 18: Edward syndrome
  • Trisomy 13: Patau syndrome
18
Q

What percentage of Down Syndrome is due to meiotic nondisjunction?

A

95%

19
Q

Why is it that it is most likely that it is through the mother that NDJ errors occur?

A

Because meiosis I is suspended for such a long time
- Also why advanced maternal age increases the chances of trisomy

20
Q

How can you differentiate between trisomy caused by NDJ in Meisosis I vs Meiosis II?

A

Meiosis I NDJ chromosomes will all be different
- Meiosis II NDJ - 2 chromosomes will be identical

21
Q

What is uniparental disomy?

A

When the child has 2 copies of 1 parent’s chromosomes

22
Q

What is uniparental disomy?

A

Child has 2 copies of 1 parent’s chromosomes
- No copies of other parent’s chromosomes

23
Q

What is isodisomy?

A

Uniparental disomy
- 2 copies of same chromosome (meiosis II error)

24
Q

What is heterodisomy?

A

Uniparental disomy
- Meiosis I error, chromosomes are different

25
Q

What is the phenotypical features of a child affected by uniparental disomy?

A

Usually has a normal phenotype
- Can lead to phenotype of recessive disease

26
Q

How many chromosomes do children with uniparental disomy have?

A

Normal number of chromosomes
- Child is ‘euploid’

27
Q

What kind of chromosomes have robertsonian translocations?

A

Acrocentric chromosomes
- Centromere near end (short short arm)

28
Q

What is robertsonian translocation?

A

Fusion of long arms of 2 chromosomes

29
Q

What chromosomes are acrocentric (centromere near end)?

A

13, 14, 21, 22

30
Q

What is a less common cause of down syndrome?

A

Robertsonian translocation

31
Q

What are the most common robertsonian translocations?

A
  • 13-14
  • 14-21
32
Q

What are the clinical consequences of people with a carrier robertsonian translocation?

A
  • Many monosomy and trisomy gametes
  • Frequent spontaneous abortions
  • Carrier may have child with Down Syndrome (trisomy 21)
33
Q

Why are those with robertsonian translocations usually have a normal phenotype?

A

Only lose short arms

34
Q

How many chromosomes do people with a carrier robertsonian translocation have?

A

45 (one translocated)

35
Q

How can a robertsonian translocation be diagnosed?

A

Karyotyping

USMLE Biochemistry (44 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions