Lecture 06 Flashcards Preview

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Flashcards in Lecture 06 Deck (23)
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1
Q

How many rounds of cell division and DNA synthesis are undergone during gamete production?

A

2 rounds cell division

1 round DNA replication

2
Q

When do homologous chromosomes separate?

A

Anaphase I

3
Q

When do sister chromatids separate?

A

Anaphase II via separase

4
Q

Leptotene stage of Prophase I

A

Homologs begin to condense/pair

5
Q

Zygotene stage of Prophase I

A

Homologs pair, synaptonemal complexes form

6
Q

Pachytene stage of Prophase I

A

Synapsis is complete; crossing over occurs

7
Q

Diplotene stage of Prophase I

A

Synaptonemal complex begins breaking down, homologs begin to separate, but remain attached at chiasma

8
Q

Diakinesis stage of Prophase I

A

Reach maximum condensation; separation of homologs and transition stage into metaphase

9
Q

Synaptonemal complex

A

Include transverse filaments (important for crossing over) and cohesin complexes (segregating homologs)

10
Q

Nondisjunction

A

Homologs fail to separate properly - leading cause of spontaneous abortions and mental retardation in humans

11
Q

Aneuploid

A

Cells with abnormal chromosome number such as Trisomy 21

12
Q

Which type of meiotic error/s is the egg generally responsible? Why?

A

Nondisjunction, aneuploidy; long arrest in meiosis I

13
Q

Which type of meiotic error/s is the sperm generally responsible for? Why?

A

DNA mutations (specifically point mutations) due to more mitotic cell divisions

14
Q

What determines whether the gonad is an ovary or testes?

A

Sex chromosomes in the genital ridge

15
Q

Sry gene

A

Sex determining region of Y; causes cells to differentiate into Sertoli cells in concert with Sox9

16
Q

What is the default pathway for gonadal development?

A

Development as a female

17
Q

When is the primary oocyte arrested, and when does meiosis resume?

A

Prophase of Meiosis I; Resumes at ovulation

18
Q

When is the secondary oocyte arrested, and when does it complete meiosis?

A

Metaphase II; Resumes after fertilization

19
Q

When does meiosis begin in sperm?

A

Puberty

20
Q

What are the requirements for capacitation?

A

Albumin, Ca2+, HCO3- to extract cholesterol and activate adenyl cyclase to produce cAMP

21
Q

Cortical reaction

A

Cortical granules release contents; prevents polyspermy by inactivating ZP3, cleaves ZP2 to make egg impenetrable

22
Q

What does sperm contribute to zygote?

A

Centrosomes and centrioles

23
Q

ICSI (Intracytoplasmic sperm injection)

A

Form of IVF where egg is injected with a single sperm; helpful for men with few motile sperm