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Developmental Biology > Gametogenesis and Fertilization > Flashcards

Gametogenesis and Fertilization Flashcards

Exam 2 (88 cards)

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1
Q

What happens to the sperm organelles after sperm cell-egg fusion?

  • Centriole
A

Mitotic spindle to complete meiosis

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2
Q

What is the acrosome?

A

Part of the sperm head (with nucleus) that contains enzymes to digest extracellular coats surrounding egg

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3
Q

Advantages of undergoing capacitation? (5)

A
  • Recognizing guiding cues to egg
  • hyperactivation
  • chemotaxis
  • perform acrosomal rxn
  • fusion with egg membrane
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4
Q

Compare oogenesis and spermatogenesis: Transcription and recombination

A

Oogenesis: Equivalent transcription & recombination

Spermatogenesis: Excluded from recombination and transcription

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5
Q

Mammalian Egg Anatomy (5)

A
  1. Ovum
  2. Cumulus
  3. Polar body
  4. Zona pellucida
  5. Cortical granule
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6
Q

What are spermatids?

A

Haploid sperm cells following the second meiotic division

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7
Q

What happens to the sperm organelles after sperm cell-egg fusion?

  • Flagellum
A

Degraded

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8
Q

How are sea urchin sperm able to locate eggs even though both types of gametes are released into a potentially large surrounding body of water, such as the open ocean?

A. Using sperm-activating peptides (SAP)
B. By sensing appropriate currents
C. By the ability of mature sea urchins to sense and approach others prior to gamete release
D. Using chemotactic agents released by sperm to bind to eggs

A

A. Using sperm-activating peptides (SAP)

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9
Q

Define Metaphase 1 in meiosis.

A

Homologous pairs line up at the equator of the cell

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10
Q

What happens to the sperm organelles after sperm cell-egg fusion?

  • Nucleus
A

nucleus decondensation &
chromatin remodeling to form male pronucleus

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11
Q

During what stage in do mammalian sperm cells lose cytoplasm and undergo additional modifications to enable motility and penetration of an egg?

A. Proliferative mitosis
B. Spermiogenesis
C. Crossing over
D. The termination of meiosis II

A

B. Spermiogenesis

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12
Q

What is Ovastacin?

A

Protease released in mammalian eggs after fertilization to digest ZP2

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13
Q

Bindin function and process in development

A

Process: Acrosomal process of sea urchin sperm

Function: Mediates the species-specific recognition between the sperm and the egg vitelline envelope during fertilization

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14
Q

What structure contains the enzymes needed by sperm to penetrate external egg structures?

A. The axoneme
B. The acrosome
C. The end piece
D. The centrioles

A

B. The acrosome

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15
Q

What are sperm activating peptides (SAPs)?

A

Chemoattractant that allows sperm of the same species to find the correct egg

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16
Q

What are Primary spermatocytes?

A

Cells are derived from the mitotic division of the type B spermatogonia

  • Undergo a period of growth and then enter meiosis
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17
Q

What is the cumulus?

A

Layer of cells surrounding the egg that nurture the egg until it is released from the ovary

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18
Q

What is the fertilization envelope formed in external fertilization?

A

Forms from the vitelline envelope of the sea urchin egg following cortical granule release

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19
Q

Why do immature sperm need to undergo capacitation?

A

Get held up in the cumulus matrix

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20
Q

Define Telophase 1 in meiosis.

A

Homologous chromosomes are segregated into 2 cells

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21
Q

What is the cortical granule reaction in preventing polyspermy in external fertilization?

A

Cortical granule enzymes contribute to the formation of a fertilization envelope to block further sperm entry

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22
Q

Fate of gonocytes XY vs XX

A

XY: Arrest in mitosis
XX: Arrest in meiosis

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23
Q

What is Spermatogonia?

A

Sperm stem cells

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24
Q

What is the axoneme?

A

Portion of a cilium or flagellum

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25
What is hyperactivation?
Increased and more forceful motility displayed by capacitated sperm
26
What is believed to aid in the prevention of polyspermy in **mammals**? A. An electrical response to the fusion of sperm and egg membranes. B. The intake by the egg of Zinc. C. The release of protein-digesting enzymes from cortical granules. D. The inhibition of ovastacin.
C. The release of protein-digesting enzymes from cortical granules.
27
What is polyspermy?
Entrance of more than one sperm during fertilization
28
What are cortical granules?
Contain enzymes to prevent polyspermy *THINK: ZPs*
29
What is spermatogenesis?
The production of sperm
30
Describe the sperm movement to egg in mammals (3)
**- Uterus contraction** (moving sperm up) **- Sperm motility** (ability of sperm to move efficiently) -** Sperm rheotaxis** (moving against current)
31
How does sperm cell fuse with the egg membrane in mammals?
Acrosomal rxn w proteins located on outside of sperm (AKA equatorial region) Lateral fusion
32
What is the pronucleus?
Male and female **haploid nuclei within a fertilized egg** fuse to form the zygote nucleus
33
What is monospermy?
Only one sperm enters the egg
34
Compare oogenesis and spermatogenesis: Initiation
**Oogenesis**: Once per lifetime **Spermatogenesis**: Continuously dividing
35
What is capacitation?
Mammalian immature sperm to mature sperm
36
Describe the steps during external fertilization (7)
1. Egg releaves sperm-activating peptides and chemotaxis 2. Sperm contacts jelly layer 3. Acrosome reaction 4. Acrosome process 5. Digestion of jelly layer 6. Binding to vitelline envelope via bindin 7. Fusion of acrosomal process membrane & egg membrane via fertilization cone
37
What is crossing over?
The exchange of genetic material during meiosis... i.e. Genes from one chromatid are exchanged with homologous genes from another
38
Does a zygote prophase exist?
No; after fusion it goes straight to mitosis
39
What occurs in the transition between PGC to Germ Cells?
XX: Retinoic acid (RA) → Stra8/Wnt4 → Meiosis XY: RA → Fgf9 --| Stra8 --| Meiosis
40
Compare oogenesis and spermatogenesis: Meiosis arrested
**Oogenesis**: first meiotic prophase **Spermatogenesis**: No cell cycle arrest
41
What are gonocytes?
differentiated PGCs but not fully differentiated gametes
42
Explain the consequence of intracellular calcium release on the egg during the external fertilization (5)
- Egg activates - Lipid metabolism to form new PM - Protein synthesis - DNA replication - Resumption of meiosis
43
What is oocyte?
Development of the egg (ovum)
44
How long does spermatogenesis take?
65 days
45
Explain gene imprinting in mammals (key terms: paternal allele, maternal allele, silencing)
Silencing of parent-specific alleles to **control embryonic growth** via differences in **DNA methylation** Parental alleles associated with growth (silencing of maternal allele equivalent) Maternal alleles associated with suppressing growth
46
Sea Urchin Egg Anatomy (5)
1. Female pronucleus 2. Egg cell membrane 3. Vitelline envelope 4. Jelly coat 5. Cortical granule
47
Which of the events listed is one of the events enabled by capacitation? A. The acrosome reaction B. The arrangement of cumulus cells around the egg C. Movement of cilia in the oviduct D. Initiation of the slow block to polyspermy
A. The acrosome reaction
48
Define Anaphase 1 in meiosis.
**Homologous chromosomes** are **pulled apart** and move to opposite poles
49
Comparison between chicken and human egg
Chicken have more yolk
50
What is meiosis 2?
MAT2; the separation of the **Sister chromatids**
51
Describe the different phases of oogenesis (6).
**IN EMBRYO** 1. Oogonia 2. Primary oocytes (step: meiotic phase) **PUBERTY** 3. Secondary oocytes (@ puberty, meiosis 1) 4. Arresting in M2 5. Maturation 6. Egg/ovum
52
Wnt Signaling Pathway Steps (6 steps, 5 arrows)
**Wnt** ↓ *(binds)* **Frizzled** ↓*(Recruits)* **Dishevelled (Dsh)** ┴ *(Recruits)* **GSK3** ┴ *(Phosphorylates, target for degration)* **B-catenin** ↓ *(To nucleus)* **Activates transcription w/ TCF/Lef**
53
What happens to the sperm organelles after sperm cell-egg fusion? - Mitochondria
Degraded
54
What is oogonia?
XX Germ line cells that become oocytes.
55
What occurs during the acrosomal reaction?
Fusion of the sperm acrosome with the sperm cell membrane to result in the acrosomal process
56
Why do the primary oocytes arrest before fertilization? During what stage does this occur?
So they can focus on transcription/translation Metaphase 2
57
Explain the steps of polyspermy (3 steps)
- Each sperm contributes centriole --> created an **additional spindle pole** - Causes improper chromosome alignment during **first mitosis** - Results in **aneuploidy in daughter cells of zygote**
58
What occurs from spermatids --> sperm cells?
Incuded by RA (sertoli cells), thus inducing meiosis
59
Which of the following refers to the silencing of parent-specific alleles during early development? A. Germ-cell inhibition B. Sex-specific repression C. Genomic imprinting D. Splicing
C. Genomic imprinting
60
What is the calcium wave to polyspermy during external fertilization?
Calcium ions moves in "waves"first near sperm entry and them throughout egg
61
What is the end product of meiosis?
4 haploid cells (23 chromosomes) Note: 23 from mother, 23 from father to have DIPLOD cells (46 chromosomes)
62
How do sperm cross the cumulus and the zona pellucida?
Via hyperactivation and enzymes from acrosome
63
What determines which cells will become germ cells?
Pole cells in the posterior side embryo
64
External fertilization: What does species-specific sperm attraction mean?
Cannot fertilize cross species. Ex: Mouse sperm cannot fertilize human
65
Is there DNA synthesis between M1 and M2?
No
66
How long does it take for slow block to polyspermy during external fertilization to occur?
Takes place about 1 minute after fast block
67
What is Spermiogenesis?
Sperm maturation
68
List how polyspermy is prevented during external fertilization
1. Fast block (Na+ membrane potential) 2. Cortical granules 3. Calcium sparks and wave
69
What causes the fertilization cone?
Polymerization of actin in sperm during acrosomal process
70
List the organelles of the sperm cell (5)
1. Acrosome 2. Axoneme 3. Nucleus 4. Centrioles 5. Mitochondria
71
How does fusion of the male and female pronuclei occur in external fertilization?
Male nucleus rotation and migration to female pro-nucleus. Connected at the **internuclear bridge** to form zygote diploid nucleus DNA and protein synthesis occurs
72
Compare oogenesis and spermatogenesis: Completion of meiosis delays
**Oogenesis**: Months or years **Spermatogenesis**: Days or weeks
73
Describe the different phases of spermatogenesis (6)
1. Spermatogonia (step: differentiation) 2. Primary spermatocytes (steps: meiosis) 3. Secondary spermatocytes 4. Spermatids (steps: spermiogenesis) 5. Residual bodies 6. Sperm cells AKA Spermatozoa
74
What is the first polar body?
Smaller cell produced that is mostly cytoplasm
75
Sperm capacitation in mammals mechanism steps (2 pathways, 4 total steps)
**1. Albumin removes cholesterol** (↑ membrane fluidity) ↓ **2. Opens Ca2+ channels** ↓ phosphorylation of sperm Mature sperm AT THE SAME TIME **1. Progesterone receptors** ↓ degrade inhibitor **2. Opens Ca2+ channels**
76
Compare oogenesis and spermatogenesis: Number of games produced
**Oogenesis**: One per meiosis **Spermatogenesis**: 4 per meiosis
77
Do mammals have a fast-block to prevent polyspermy?
No
78
List the steps of meiosis (8)
1. Interphase (DNA synthesis) 2. Prophase 1 3. Metaphase 1 4. Anaphase 1 5. Telophase 1 6. Metaphase 2 7. Anaphase 2 8. Telophase 2
79
FGF and RTK Signaling Pathway Steps (9 steps; 7 arrows)
**FGF** ↓ *(binds)* **Tyrosine Kinase Receptor** ↓*(Dimerization, phosphorylation, recruit/activate)* **GAP / GEF** ┴ *(GTP to GDP = inhibit)* / ↓**(GDP to GTP = activates)* **RAS** ↓ *(recruits)* **Raf** ↓ *(Phosphorylates)* **MEK** ↓ *(Phosphorylates)* **ERK** ↓ *(To nucleus and phosphorylates)* **Ets fam transcription factors** ↓ **Regulate transcription**
80
When does gametogenesis occur in humans?
12-14 dpf
81
Define prophase 1 and its 4 steps
1. **Leptotene**: Chromosomes start to condense 2. **Zygotene**: Homologous chromosomes pair up 3. **Pachytene**: Crossing over occurs 4. **Dipotene**: Synaptonemal complex dissolves but remain attached at crossing-over points *THINK: "Lazy Zebras Play Dodgeball"*
82
What is fast block to polyspermy during external fertilization?
**Additional sperm are prevented** from fusing with egg by **changing the electric potential** Negative inside (less Na+)--> Sperm enters --> Na+ channels open --> More positive inside
83
What is the cortical flash and wave in polyspermy prevention during external fertilization? List the steps involved (6)
Influx of calcium ions into the egg's cytoplasm before moving throughout egg Bindin ↓ (binds) TK receptor ↓ (activates) PLC ↓ (activates) IP3 ↓ (binds) IP3 receptor in Ca2+ channels ↓ (opens channels) Ca2+ released from ER to cytoplasm
84
Vitelline envelope vs zona pellucida
**Vitelline Envelope**: Surrounds egg (NOT MAMMALIAN) **Zona Pellucida**: Surrounds the mammalian egg
85
What occurs during the acrosomal process?
**Fingerlike process** in sperm head extended that **contains surface molecules for species-specific recognition** between sperm and egg
86
What is the fertilization cone?
Location where the egg and sperm fuse during fertilization
87
What are the secondary oocytes?
Oocyte after first meiotic division that **generates first polar body**
88
Describe the cause and the event happening upon egg activation in mammals.
Ca2+ pulses --> complete meiosis --> form female pronucleus

Developmental Biology (4 decks)

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