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Human Genetics > Lecture 1: Meiosis and Gametogenesis > Flashcards

Lecture 1: Meiosis and Gametogenesis Flashcards

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1
Q

True or False: Chromosomal abnormalities due to meiotic errors are the leading cause of miscarriages and intellectual disability syndromes

A

True

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2
Q

Label the following:

A
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3
Q

Which stage of mitosis are you looking at?
A. Cytokinesis
B. Telophase
C. Anaphase
D. Metaphase

A

D. Metaphase
- condensed chromosomes are only observed at metaphase

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4
Q

____: process of nuclear division by which a mother cell generates two daughter cells of identical genetic composition

____: specialized nuclear division that produces a haploid cell from a diploid precursor

A

Mitosis

Meiosis

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5
Q

True or False: Cytokinesis is the division of the cytoplasm

A

True

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6
Q

Microtubules attach to the ___, which are structures mounted on top of the centromeres

A

Kinetochores

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7
Q

True or False: Microtubule depolymerization is required to shorten tubulin structures and pull the chromosomes towards the centrosomes

A

True

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8
Q

Which stage of mitosis corresponds to the following: “Chromosome condensation and mitotic spindle formation”
A. Prometaphase
B. Metaphase
C. Prophase
D. Telophase
E. Anaphase

A

C. Prophase

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9
Q

True or False: The nuclear envelope is disassembled in prometaphase

A

True

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10
Q

At what stage of mitosis do centromeres and kinetochores split and sister chromatids begin migrating to opposite sides of the poles?

A

Anaphase

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11
Q

At what stage of mitosis do spindles and kinetochores disassemble, nuclear envelop forms, and chromatids decondense?

A

Telophase

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12
Q

True or False: Homologous chromosomes are involved in mitosis

A

False - SISTER CHROMATIDS

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13
Q

True or False: Meiosis involves one round of nuclear division and two rounds of DNA replication

A

True!

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14
Q

True or False: If gametes do not undergo a reduction from diploid to haploid before fertilization, the gametes will be quadraploid (n=4)

A

True

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15
Q

What is the longest stage of Meiosis I?

A

Prophase I

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16
Q

At which stage of Meiosis I does the chromosome condense and the kinetochores and spindles form?

A

Prophase I

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17
Q

At what stage of Meiosis I do chromosome homologs migrate to opposite poles?

A

Anaphase I

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18
Q

True or False: Separation of SISTER CHROMATIDS occurs at Meiosis I while separation of CHROMOSOME HOMOLOGS occurs at Meiosis II

A

False -

Meiosis I: separation of chromosome homologs

Meiosis II: separation of sister chromatids

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19
Q

Synapsis and Chismata occur at which phase of Meiosis I?

A

Prophase I

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20
Q

At which stage of Meiosis I do the kinetochores and spindles dis-assemble; nuclear envelop forms; and chromatids de-condense?
A. Metaphase I
B. Prophase I
C. Telophase I
D. Anaphase I

A

C. Telophase I

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21
Q

At what stage of Meiosis I does meiotic recombination occur?
A. Metaphase I
B. Prophase I
C. Telophase I
D. Anaphase I

A

B. Prophase I

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22
Q

True or False: Meiotic recombination involves enzyme-mediate DNA double stand break, as well as sister chromatids to repair DSB

A

False - while meiotic recombination involves enzyme mediate dsDNA breaks, chromosome HOMOLOGS are used to repair DSB

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23
Q

Which of the following mechanisms of repair is faster and more mutagenic, requiring NO homology for repair?
A. Non-Homologous End Joining Repair
B. Homologous Recombination Repair

A

A. Non-Homologous End Joining Repair

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24
Q

Which mechanism of repair requires a SISTER CHROMATID as a template for repair?
A. Non-Homologous End Joining Repair
B. Homologous Recombination Repair

A

B. Homologous Recombination Repair

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25
Q

True or False: There is NO exchange of genetic info in Homologous Recombination Repair because template is an exact copy of damaged chromosome

A

True

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26
Q

True or False: Meiotic recombination only occurs in somatic cells

A

False - germ cells only

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27
Q

Which enzyme mediates and programs dsDNA breaks in meiotic recomb?

A

Spo11

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28
Q

In meiotic recombination, recombination occurs between ____ ___

A

chromosome homologs

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29
Q

True or False: There is not an exchange of genetic material in meiotic recombination

A

False - there IS an exchange of genetic material because recombination occurs between chromosome HOMOLOGS

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30
Q

Why does homologous recombination only occur during S and G2 phase of the cell cycle?

A

Because it requires a sister chromatid as a repair template

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31
Q

True or False: Defects in Homologous Recombination repair can lead to increased cancer susceptibility

A

True

32
Q

Which pathway requires resection of DNA ends to generat ssDNA region that will be used to recombine with SISTER CHROMATID
A. Homologous Recombination Repair
B. Non-Homologous Recombination Repair

A

A. Homologous Recombination Repair

33
Q

True or False: In meiotic recombination (prophase I), the chromosome homologs will recombine

A

True

34
Q

True or False: Spo11 topoisomerase II-like protein will induced DSB’s

A

True

35
Q

What are the four stages of Prophase I?

A

Leptonema, Zyginema, Pachynema, Dipolnema

36
Q

True or False: Sister chromatids are identical copies of each other

A

True

37
Q

___: a pair of chromatids after DNA replication joined together by a centromere

A

Sister chromatids

38
Q

True or Cells: Daughter cell produced via mitosis are diploid while daughter cells produced via meiosis are haploid

A

True

39
Q

At what phase of Prophase I does the synaptonemal complex become established?
A. Leptotene
B. Zygotene
C. Pachytene
D. Diplotene

A

A. Leptotene

  • pairing between chromosome homologs also occurs
40
Q

At what phase of Prophase I does the synapsis along the chromosome homologs occur and the SC is fully formed?
A. Leptotene
B. Zygotene
C. Pachytene
D. Diplotene

A

B. Zygotene

41
Q

True or False: Most double stranded DNA breaks are repaired through homologous recombination

A

False - most are repaired via: non-crossover pathways

42
Q

True or False: double stranded DNA breaks that are repaired via homologous recombination result in crossovers

A

True

43
Q

At what phase of Prophase I does meiotic recombination occur and chiasmata is formed (physical linkage of chromatids)
A. Leptotene
B. Zygotene
C. Pachytene
D. Diplotene

A

C. Pachytene

44
Q

True or False: The SC breaks down and chromosomes begin to separate, but remain held together at the chiasmata at the Diplotene stage of Prophase I

A

True

45
Q

True or False: The synaptonemal complex is only observed during prophase I of meiosis

A

True

46
Q

What is the function of the SC (synaptonemal complex)?

A

Maintains chromosome homologs held together through recombination process

  • note: SC defects can result in infertility or subfertility
47
Q

Compare and contrast mitosis and meiosis:

A
48
Q

___: DNA structures that hold chromosome homologs together and counteract pulling forces of meiotic spindle

A

Chiasmata

49
Q

In prophase I, there is crossover assurance, which ensures ____. There is also crossover interference, which ensures ______.

A

Crossover Assurance: At least one CO per chromosome

Crossover Interference: No two COs will be too close together

50
Q

How can we ensure that the
offspring is genetically
unique?

A

1) Independent assortment of
chromosome homologs

2) Genetic recombination
between chromosome
homologs

51
Q

True or False: Crossing over and meiotic recombination results in exchange of genetic information between maternal and paternal chromosomes

A

True

52
Q

____: process by which MT’s pull an extra
chromatid to one pole, which
results in one daughter cell with
an extra copy of a chromosome
and another missing one copy of
a chromosome

A

Non-disjunction

53
Q

True or False: In non-disjunction, the formation of chiasmata
prevents early separation of
chromosome homologs (1 per
chromosome minimum)

A

True

54
Q

Absence of crossing over could lead to random ___ and ___, which results in embryonic death or developmental defects

A

disjunction; aneuploidy

55
Q

True or False: Most gametic aneuploid originates during oogenesis during first meiotic division

A

True

56
Q

True or False: Aneuploid in gametes is major cause of miscarriages and birth defects

A

True

57
Q

___: structures that resist spindle forces before anaphase I and hold chromosome homologs together, thus ensuring proper chromosomal segregation

A

Chiasma

58
Q

True or False: Gametogenesis occurs in the gonads of mammals

A

True

59
Q

Male mammals are born with spermatogonial stem cells that continuously proliferate through mitosis. At puberty, a cohort of this stem cell population matures into which cell type?

A

Primary spermatocytes (diploid

60
Q

Male mammals are born with spermatogonial stem cells that continuously proliferate through mitosis. At puberty, a cohort of this stem cell population matures into which cell type?

A

Primary spermatocytes (diploid precursor cell)

61
Q

Primary spermatocytes undergo meiosis to produce ___, which undergo meiosis II to produce four ____, which eventually become sperm cells

A

secondary spermatocytes, spermatids

62
Q

A ___ is a mature haploid germ cell capable of fusion with another haploid germ cell; during sexual reproduction, produces a diploid zygote

A

gamete

63
Q

Spermatogenesis occurs in the ____

A

testes

64
Q

Primary spermatocytes undergo ____ while secondary spermatocyte undergo _____

A

1 spermatocytes = meiosis I
2 spermatocytes = meiosis II

65
Q

True or False: Spermatogonia are considered stem cells, replicate mitotically, and are located in outer layer of seminiferous tubules

A

True

66
Q

True or False: Spermatids undergo maturation

A

True

67
Q

Which oocyte is arrested at prophase I until ovulation?

A

1 oocyte

68
Q

Upon ovulation, meiosis I is completed and arrest at ___ occurs

A

meiosis II

69
Q

When will the secondary oocyte undergoes meiosis II?

A

Upon fertilization by a spermatozoid

70
Q

The mature ovum will fuse with a ___ and form a zygote

A

spermatozoid

71
Q

Non-disjunction can occur during oogenesis. When it occurs, microtubules pull both pairs of sister chromatids to one pole, which result in one oocyte with an ___ copy of a chromosome and another missing one copy of a chromosome

A

extra

72
Q

True or False: The formation of the chiasmata in oogenesis prevents premature separation of chromosome homologs

A

True

73
Q

Prolonged arrest in ____ is thought to result in weakened chromosomal interactions thus leading to increased meiotic errors in aged oocytes

A

prophase I

74
Q

compare and contrast oogenesis and spermatogenesis

A
75
Q
A

Human Genetics (7 decks)

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