Brainscape's Knowledge GenomeTM

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


See full index

Mol / Cel Biology > Lecture 9 > Flashcards

Lecture 9 Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Gametogenesis is… (the process)

A

Development of haploid sex cell:

mature oocyte and sperm cell in a diploid organism by meiosis.

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

Origin of gametes? (timeline)

A

At about 4 weeks of pregnancy.

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

Sex cell precursors? And where they arise?

A

PGC (primordial germ cells) arise in the yolk sac to genital bridge (bisexual gonads).

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

When does PGC migrate to genital ridge - bisexual gonads? (timeline)

A

4-6 week of pregnancy

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

Early migration of PGC’s is dependent on expression of what?

A

The expression of ITProteins 1 and 3.

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

What is SRY (the male determining pathway)?

A

Sex-determining region on the Y chromosome (obviously males).

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

What is the main role of SRY?

A

Up-regulating the expression of SOX9 during a very narrow critical time window.

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

In human SRY is expressed in both (cells)?

A

Sertoli cells and germ cells at fetal and adult stages.

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

What is SOX9 (protein what)?

A

Gene on autosome, activated by SRY

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

SOX9 is expressed at low levels in?

A

Bipotential gonads of both sexes under SF1 regulation.

Because the gender is not determined yet.

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

Some oocyte and sperm genes are imprinted differently because (passage to generations)?

A

Because germ cell genes, but not somatic cell genes, are passed on to the next generation:
- imprinted marks present in the zygote must be erased then -> reset at some point during germ cell development
- in the somatic cells of the developing embryo, these
same imprinted marks must be retained

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

X-chromosome re-activation?

A

In female’s PGC (2n).

2 X chromosomes are active (inactivated X is
reactivated).

Reduction of Xist RNA levels

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

Timing of gametogenesis in males and females:

A

In males – starts at puberty and continues
throughout adult life

In females – starts during embryonic life (before birth) and ends for each particular oocyte after
fertilization (menopause).

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

Oogenesis happens by:

A

Mitosis and meiosis both.

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

Modified meiosis consists of (oogenesis / what stops)?

A

2 arrests (stops):

In Meiosis I (prophase I -> diplotene)

In Meiosis II (metaphase II)

Meiosis II can be finished only AFTER the fertilization

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

Periods of oogenesis are?

A

Proliferation period.
Growth period.
Maturation period.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Proliferation period happens (when and what steps involved)?

A

3rd month of embryonic development.
From PGC → oogonia (2n).
Primary oogonia → secondary oogonia.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Growth period happens (when and what steps involved)?

A

4-6 month of embryonic development

Secondary oogonia → Primary oocytes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Maturation period happens (when and what steps involved)?

A

7-8 month of of embryonic development.

Meiosis I. STOP at diplotene.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Put in real order of oogenesis meiosis I: zygotene, pachytene, leptotene, diplotene and STOP

A

Leptotene, zygotene, pachytene, diplotene and

STOP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Primary oocytes in embryonic ovaries are surrounded by (what cells)?

A

Follicular cells. They form an embryonic follicle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What happens postnatal period (after birth) - at the time of birth:

A

Primary oocytes remain in diplotene till the puberty.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What happens postnatal period - at the puberty:

A

400 000 primary oocytes.
Embryonic (primordial) follicles → primary follicles.
Maturation of primary oocytes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Primary follicle consists of (?+?):

A

Oocyte I + follicular cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Primary follicle structure:

A 
Oocyte I:
- Plasmatic membrane
- Nucleus
- Cytoplasm
- Zona pellucida
One layer of follicular cells.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What happens to the oocyte at the puberty?

A

Every month 5-15 oocytes I start maturation.
Only one will mature in the end.
Primary follicles → secondary (developing) follicles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Secondary follicle structure? (2nd follicle developed from the 1st)

A
  • Oocyte I
  • Zona pellucida
  • Several layers of follicular cells
  • Anthrum enlarges
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Mature follicle structure? (developed from 2nd follicle)

A
  • Oocyte I
  • Zona pellucida
  • Differentiation of follicular
    cells:
    »Corona radiata
    »Cumulus oophorus
  • Anthrum is enlarged more
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What happens in maturation period of oocytes?

A

Only one oocyte I finishes meiosis I and develops to:

One oocyte II (n), that continues with meiosis II and stops in metaphase II and one first polar body (n).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Cytokinesis happens by help of? (Oogenesis)

A

Actin – myosin contractile ring.
Cytokinesis is UNEQUAL, but COMPLETE.

In Meiosis I: one large cell – oocyte II (n) and
one small cell – polar body (n)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Regulation of meiosis in oogenesis is controlled by:

A

MPF complex of Cdk2 and cyclin B.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

After fertilization? (Oogenesis)

A

Oocyte II continues in meiosis II.

One large cell: mature oocyte II (egg) and small cell – polar body (n).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What happens in absence of fertilization?

A

Oocyte II stays in metaphase II of meiosis II.
Secreting hormones, promotes development of the
next oocyte.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Follicular cells consists of? (2)

A

Granulosa cells. Theca cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Granulosa cells:

A

Produce sex hormones – estrogen and progesterone.

Produce different growth factors.

36
Q

Theca cells:

A

Internal – Theca interna – produce androgenes and
progesterone.
External – Theca externa – connective tissue, important in the ovulation.

37
Q

Result of oogenesis is in a nutshell:

A

One mature oocyte II (n) and polar bodies, which are not used in fertilization.

38
Q

The main function of polar bodies is:

A

To reduce the chromosome number.

39
Q

Oogenesis occurs:

A

From 3rd month of embryonic life till the menopause

40
Q

Spermatogenesis starts at:

A

Puberty and continues through life time. One cycle last +- 70 days.

41
Q

Spermatogenesis occurs:

A

In testes (semineferous tubules).

42
Q

Why don’t spermatogonia enter meiosis?

A

In human fetal testis, CYP26B1 does not seem to be
expressed.
During embryonic life Sertoli cells produce
inhibitor of meiosis – PG D2

43
Q

At the time of birth sex cells are located in?

A

Sex cords.

44
Q

Sertoli cells: Tall columnar epithelial cells structures? Aika jolloin sperma ilman häntää :)

A
  • with large nucleus,
  • abundant in euchromatin,
  • well developed Golgi complex
  • many mitochondria (Mt)
  • extended smooth ER
45
Q

Sertoli cells functions:

A
  • Surround developing sperm cells.
  • Secrete proteins and fluids, growth.
  • Trophic function
  • Synchronize the events of spermatogenesis.
46
Q

Spermatogenesis periods:

A

Proliferation.
Growth.
Maturation.
Spermiogenesis.

47
Q

Proliferation period (when and what steps involved)? (Spermatogenesis)

A

Begins in embryonic life and continues through
life time.
During embryonic life Sertoli cells produce
inhibitor of meiosis – PG D2.

PGC → primary (A) spermatogonia (2n).
Primary spermatogonia → secondary (B)
spermatogonia (2n).

48
Q

Growth period (when and what steps involved)? (Spermatogenesis)

A

Begins in puberty.
Secondary spermatogonia grow → primary spermatocytes (2n)-
Growth period is weak comparing to oogenesis

49
Q

Maturation period (when and what steps involved)? (Spermatogenesis)

A

Two meiosis.

Lasts for 22-24 days.

50
Q

Role of syncytium: (Cytoplasmic bridges)

A

Akap82 protein – important in tail formation.

Akap82 gene is located on X chromosome.

51
Q

What is different in cytokinesis of spermatogenesis?

A

Cytokinesis is EQUAL, but INCOMPLETE.

  • Two cells of identical size
  • Male’s sex cell precursors remain joined by cytoplasmic bridges.
52
Q

Steps of spermiogenesis? (Not periods)

A
  • Formation of an acrosome
  • Nuclear morphogenesis
  • Formation of tail structures
  • Rearrangement of organelles
  • Sheding most of the cytoplasm
53
Q

Formation of an acrosome:

A

Formed from Golgi complex.
Enzymes allow sperm to
penetrate oocyte.

54
Q

Nuclear morphogenesis:

A

Changes in shape (from round to oval).
Becomes more dense.
Chromatin condensation.
Sperm specific histones are produced.

55
Q

Formation of tail structures:

A

Elongation of microtubules.

Distal centriole elongates.

56
Q

Rearrangement of organelles:

A

Mitochondria fuse and form spiral around of the tail.

57
Q

Sperm functions:

A

To deliver its set of genes to the egg.

To activate the egg.

58
Q

Abnormal sperm and sperm production syndromes:

A

Azoospermia:
» no sperm in semen (ejaculate)
Oligozoospermia:
»low sperm count (< 20 million spermatozoa per ml of ejaculate)
Sertoli cell only syndrome:
» in seminiferous tubules only Sertoli cells

59
Q

Beginning and ending: (Spermatogenesis vs. oogenesis)

A

Begins at puberty, ends at death.
Vs.
Begins before birth, ends at menopause.

60
Q

Encompass how many stages? (Spermatogenesis vs. oogenesis)

A

4 stages: proliferation, growth, maturation, spermiogenesis.
Vs.
3 stages: proliferation, growth, maturation.

61
Q

Primary cycles form how many? (Spermatogenesis vs. oogenesis)

A

One primary spermatocycle forms 4 sperm cells.
Vs.
One primary oocyte forms one egg and polar bodies.

62
Q

Quantity? (Spermatogenesis vs. oogenesis)

A

Billions of sperm cells are produces at a time.
Vs.
One oocyte matures monthly.

63
Q

Cytokinesis? (Spermatogenesis vs. oogenesis)

A

Cytokinesis is not completed until the end of spermatogenesis.
Vs.
Nuclear division takes place at the very end of oogenesis.

64
Q

Acrosome undergoes exocytosis and what happens then?

A

Sperm releases digestive enzymes into

the Zona pellucida

65
Q

The sperm migrates through the coat of
the ___ ___ (Corona radiata) and binds
to a receptor molecule in the ___ ___ of the egg (secondary oocyte)

A

follicle cells

Zona pellucida

66
Q

Sperm-Egg Recognition & Binding Receptors of Zona pellucida mediators? (3)

A

ZP3 mediates sperm-specific egg binding.
ZP2 mediates subsequent sperm binding.
ZP1 important for structural integrity of Zona
pellucida.

67
Q 
With the help of
\_\_\_ \_\_\_ the
sperm reaches the egg,
and a \_\_\_\_\_\_ \_\_\_\_
(ADAM) of the sperm
binds to a receptor (ZP2)
on the \_\_\_ \_\_\_\_
A

acrosomal reaction
membrane protein
egg membrane

68
Q

The plasma membranes fuse
making it possible for sperm
cell to:

A

enter the egg

69
Q

Cortical reaction:

A

Enzymes released from corticular granules harden Zona pellucida.
Block the polyspermy (allow monospermy)

70
Q

After sperm cell enters the egg:

A

Basal body of the sperm’s flagellum divides and forms the centrioles of zygote.
Male and female pronuclei form synkaryon

71
Q

Significance of fertilization:

A

Changes in the egg`s cytoplasm are induced.
The diploid chromosome number is reestablished.
Mixing of paternal and maternal chromosomes takes place.

72
Q

What determines the sex?

A

SRY (-> Presence of Y-chromosome.) -> if present -> activates SOX9 -> Presence of Y-chromosome.

73
Q

What happens to PAR1 in chromosomes during meiosis?

A

Crossing over

74
Q

If Y-chromosome is present ->

A

Spermatogenesis

75
Q

In which period of oogenesis does the crossing over occurs?

A

During meiosis I in prophase I IN maturation period.

76
Q

In which periods of oogenesis the non-disjunction of chromosomes can occur?

A

During the maturation period of oogenesis in anaphase I.

Non-disjunction occurs in anaphase I/II.
The first non-disjunction could happen in the anaphase I of the proliferation phase in the mitosis.
The second non-disjunction could happen in anaphase I of the meiosis I.
The thrid non-disjunction could occur in the anaphase II after the fertilization.

77
Q

What is zona pellucida?

A

Zona pellucida is a glycoprotein layer surrounding the plasma membrane of mammalian oocytes.

78
Q

What does zona pellucida consists of?

A

Zona pellucida is an extracellular matrix composed of three glycoproteins: ZP1, ZP2, and ZP3.

Receptors on the sperm plasma membrane attach to ZP3. Binding to ZP3 allows the sperm to adhere to the zona pellucida and is a critical step in fertilization. It triggers the sperm head to undergo the acrosome reaction.

79
Q

What is zona pellucidas function in oogenesis and fertilization?

A

Zona pellucida supports communication between oocytes and follicle cells during oogenesis, protects oocytes, eggs, and embryos during development, and regulates interactions between ovulated eggs and free-swimming sperm during and following fertilization.

80
Q

What is Corona radiata?

A

Corona radiata is formed by follicle cells adhering to the oocyte before it leaves the ovarian follicle.

Corona radiata is formed when the granulosa cells enlarge and become cuboidal, which occurs during the transition from the primordial to primary stage.

81
Q

What does corona radiata consists of?

A

Corona radiata is the inner layer of the cells of the cumulus oophorus and is directly adjacent to zona pellucida. Its main purpose in many animals is to supply vital proteins to the cell.

82
Q

What is corona radiatas functions in oogenesis and fertilization?

A

For fertilization to happen, sperm cells rely on hyaluronidase to disperse the corona radiata from the zona pellucida of the Oocyte II.
So, it is permitting entry into the perivitelline space and allowing contact between the sperm cell and the nucleus of the oocyte.

83
Q

What is an acrosome?

A

Acrosome is an organelle that develops over the head (anteriorly) in spermatozoa (sperm cells) of animals / humans. It is a cap-like structure derived from the Golgi apparatus.

84
Q

What is acrosome significance in fertilization?

A

The function of the acrosome reaction is to help the sperm get through the egg’s protective coat and to allow the plasma membranes of the sperm and egg to fuse.
This has three major consequences: the release of proteolytic enzymes, extension of the acrosomal process, and exposure of membrane proteins.

85
Q

What is the role of centrioles of sperm cell in fertilization and what is their impact on meiosis II in oocyte?

A

Centriole serves as microtubule organizing center (MTOC) after fertilization and accumulates centrosomal components from the oocyte to form the sperm aster, zygote aster, and mitotic apparatus after fertilization.

Mol / Cel Biology (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions