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Biology Chapter 11 > Chapter 11.4 > Flashcards

Chapter 11.4 Flashcards

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1
Q

Gametogenesis

What is gametogenesis

A

Process by which diploid precursor cells undergo meiotic division to become haploid gametes

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2
Q

Gametogenesis

What is gametogenesis in males and what does it produce?

A

Spermatogenesis and produce spermatozoa

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3
Q

Gametogenesis

What is gametogenesis in females and what does it produce?

A

Oogenesis and produce ova

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4
Q

Gametogenesis

Where does the process of gametogenesis occur?

A

Gonads

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5
Q

Gametogenesis

What are the steps of gametogenesis?

A

-Multiple mitotic divisions and cell growth of precursor germ cells
-Two meiotic divisions (meiosis I and II) to produce haploid daughter cells
-Differentiation of the haploid daughter cells to produce functional gametes

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6
Q

Spermatogenesis

Where does spermatogenesis occur?

A

In the seminiferous tubules of the testes

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7
Q

Spermatogenesis

When does spermatogenesis occur?

A

Occurs at puberty where the germ line epithelium undergoes mitotic divisions to form spermatogonia

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8
Q

Spermatogenesis

What happens to spermatogonia after they have undergone mitosis?

A

They undergo cell growth to produce spermatocytes

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9
Q

Spermatogenesis

What happens to spermatocytes after the cell growth period?

A

Spermatocytes undergo two meiotic divisions to form four haploid daughter cells, spermatids

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10
Q

Spermatogenesis

What happens to the spermatids after the meiotic divisions?

A

Spermatids then undertake a process of differentiation in order to become functional sperm cells, spermatozoa

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11
Q

Oogensis

Where does oogenesis occur?

A

In the ovaries

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12
Q

Oogensis

When does oogenesis occur?

A

Begins during fetal development, when a large number of oogonia are formed by mitosis

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13
Q

Oogensis

What happens to the oogonia after they have undergone mitosis?

A

Undergo cell growth until they are large enough to undergo meiosis becoming primary oocytes

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14
Q

Oogensis

What happens to the primary oocytes during meiosis?

A

They are arrested in prophase 1 where granulosa cells surround the cells forming follicles

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15
Q

Oogensis

Till when are the primary oocytes stuck in prophase 1?

A

Until the girl hits puberty

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16
Q

Oogensis

What happens after the girl hits puberty?

A

Each month, hormones (FSH) will trigger the continued division of some of the primary oocytes

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17
Q

Oogensis

What would be the result of the first meiotic division?

A

Two cells of unequal size, one cell retains the entirety of the cytoplasm to form a secondary oocyte, while the other cell forms a polar body

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18
Q

Oogensis

What happens to the secondary oocyte after it has been produced by the primary oocyte?

A

It will start to undergo the second meiotic division and will be arrested in metaphase 2

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19
Q

Oogensis

What happens to the secondary oocyte after it has been trapped in metaphase 2?

A

Released from the ovary (ovulation) and enters into the oviduct (or fallopian tube)

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20
Q

Oogensis

What are the follicles formed around secondary oocyte and what do they serve?

A

It is a corona radiata that forms and works to nourish the seconadry oocyte

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21
Q

Oogensis

How will the secondary oocyte complete its second meiotic division?

A

If the oocyte is fertilized by a sperm, where another polar body is formed

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22
Q

Oogensis

What happens at the end of meiosis 2?

A

Mature egg form ovum, before the ovum is fused with sperm to form zygote

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23
Q

Differences between oogenesis and spermatogenesis

How is number of cells produced different in spermatogenesis and oogenesis?

A

-In spermatogenesis, the cells divide equally during meiosis to produce four functional gametes
-In oogenesis, the cells do not divide equally and as a result only one functional gamete is formed (plus 2 – 3 polar bodies)

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24
Q

Differences between oogenesis and spermatogenesis

How is the size of cells produced different in spermatogenesis and oogensis?

A

-In spermatogenesis, the cells that are formed following differentiation are all of equal size with equal amounts of cytoplasm
-In oogenesis, one daughter cell (the ovum) retains all of the cytoplasm, while the other daughter cells form polar bodies

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25
Q

Differences between oogenesis and spermatogenesis

How does the timing of the processes of spermatogenesis and oogensis differ?

A

-In spermatogenesis, the production of gametes is a continuous process that begins at puberty and continues until death
-In oogenesis, It begins before birth (prenatally) with the formation of a fixed number of primary oocytes (~40,000). It continues with the onset of puberty according to a monthly menstrual cycle. It ends when hormonal changes prevent the further continuance of the menstrual cycle (menopause)

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26
Q

Seminiferous Tubule

What is the role of seminiferous tubule?

A

The production of sperm

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27
Q

Seminiferous Tubule

What surrounds the tubules?

A

A basement membraned lined with a germline epithelium

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28
Q

Seminifiroues Tubule

What nourishes the matured sperm?

A

Sertoli cells which are found on tubule lining

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29
Q

Seminiferous Tubules

What resided outside of the tubules?

A

Leydig cells that produce testosterone

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30
Q

Ovary

What happens to the follicles within the ovary?

A

Primordial follicles will mature to form primary follicles, then secondary follicles then a dominant or Graafian follicle, which will rupture and release seconadry oocyte. The ruptured follicle will develop into corpus lutuem which will produce ovarian hormones

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31
Q

Sperm

What are the differnet sections of a spermatozoa?

A

Head, mid-piece and tail

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32
Q

Sperm

What is the head piece composed of?

A

Haploid nucleus which hold genetic information, an acrosome cap which contains hydrolytic enzymes that will penetrate jelly coat and paired centrioles which are used in order to divide

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33
Q

Sperm

What is the function of the midpiece?

A

Contains high numbers of mitochondria which provide the energy (ATP) needed for the tail to move

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34
Q

Egg

What are the layers surrounding the egg?

A

The zone pellucida (jelly coat) and corona radiata

34
Q

Sperm

What is the function of the tail?

A

The tail (flagellum) is composed of a microtubule structure called the axoneme, which bends to facilitate movement

35
Q

Egg

What is the zona pellucida?

A

The zona pellucida is a glycoprotein matrix which acts as a barrier to sperm entry

36
Q

Egg

What is the corona radiata?

A

The corona radiata is an external layer of follicular cells which provide support and nourishment to the egg cell

37
Q

Sperm

What is the function of the cortical granules?

A

Release their contents upon fertilisation to prevent polyspermy

38
Q

Animal Fertilization

What is external fertilization?

A

Involves the fusion of gametes (egg and sperm) outside of the body of a parent

39
Q

External Fertilization

Which type of animals undergo this type of fertilization?

A

Aquatic animals, as there environmment allows the gametes to travel. In addition, the environment is susceptible to environmental factors such as predators and pH changes. So they produce large quantity of gametes

40
Q

Animal Fertilization

What is internal fertilization?

A

Involves the fusion of gametes (egg and sperm) inside of the body of a parent

41
Q

Internal Fertilization

Which type of animals undergo this type of fertilization?

A

Terrestrial animals typically use internal fertilization so as to prevent exposure and desiccation of gametes or embryos, but at a potential survival cost to the parent

42
Q

Human Ferilization

What are the steps of human fertilization?

A

Capacitation, Acrosome reaction, Cortical reaction

43
Q

Capacitation

When does capacitation occur?

A

Capacitation occurs after ejaculation, when chemicals released by the uterus dissolve the sperm’s cholesterol coat, This improves sperm motility and destabilises the acrosome cap

44
Q

Acrosome Reaction

What is the acrosome reaction?

A

When the sperm reaches an egg, the acrosome reaction allows the sperm to break through the surrounding jelly coat

45
Q

Acrosome Reaction

How does the acrosome reaction happen?

A

The sperm pushes through the follicular cells of the corona radiata and binds to the zona pellucida. The acrosome vesicle fuses with the jelly coat and releases digestive enzymes which soften the glycoprotein matrix. The sperm then pushes its way through the softened jelly coat and binds to exposed docking proteins on the egg membrane. The membrane of the egg and sperm then fuse and the sperm nucleus (and centriole) enters the egg

46
Q

Cortical Reaction

When does the cortical reaction occur?

A

The cortical reaction occurs once a sperm has successfully penetrated an egg in order to prevent polyspermy

47
Q

Cortical Reaction

How does the cortical reaction happen?

A

Cortical granules within the egg’s cytoplasm release enzymes (via exocytosis) into the zona pellucida (jelly coat). These enzymes destroy sperm binding sites and also thicken and harden the glycoprotein matrix of the jelly coat. This prevents other sperm from being able to penetrate the egg (polyspermy), ensuring the zygote formed is diploid .

48
Q

Blastocyst Formation

What happens after fertilization?

A

Influx of Ca2+ into the ova prompts the completion of meiosis II, where the egg and sperm nucleus fuse to form a zygote

49
Q

Blastocyst Formation

What will happen to zygote if it undergoes mitotic divisions?

A

Form a solid ball of cells called a morula

50
Q

Blastocyst Formation

What will occur to morula when it undergoes differentitaion and cavitation?

A

Formation of a blastocyst

51
Q

Blastocyst Formation

What is the structure of the blastocyst?

A

An inner cell mass, A surrounding outer layer called the trophoblast, A fluid filled cavity called the blastocoele

52
Q

Implantation of Blastocyst

How is the implantation of the blastocyst done?

A

Blastocyst breaches the jelly coat that was surrounding it and preventing its attachment to the endometrium. Digestive enzymes are released which degrade the endometrial lining, while autocrine hormones released from the blastocyst trigger its implantation into the uterine wall

53
Q

**Implantation of Blastocyst **

How will the process of embryogenesis persist?

A

When blastocyst is implanted in uterine wall

54
Q

hCG

What is hCG

A

Promotes the maintenance of the corpus luteum within the ovary and prevents its degeneration

55
Q

hCG

From where is the hCG released?

A

From blastocyst once it has been implanted in uterine wall

56
Q

hCG

What will happen when corpus luteum does not degenerate?

A

It will keep on producing estrogen and progesterone

57
Q

**hCG **

What is the role of estrogen that is released from corpus luteum?

A

Inhibits FSH and LH production by the pituitary gland, preventing the release of more eggs from the ovaries

58
Q

hCG

What is the role of progesterone that is released from corpus luteum?

A

Progesterone also functions to maintain the endometrium (which is nourishing the embryo) and thicken the cervix

59
Q

Placenta

What is the placenta?

A

Functions as the life support system for the foetus

60
Q

Placenta

What are the 2 key functions of placenta?

A

-It facilitates the exchange of materials between the mother and foetus
-It secretes hormones to maintain the pregnancy after the corpus luteum has degenerated

61
Q

Structure of Placenta

What is the shape of the pacenta?

A

The placenta is a disc-shaped structure that nourishes the developing foetus

62
Q

Structure of Placenta

From what is the placenta formed?

A

It is formed from the development of the trophoblast upon implantation and eventually invades the uterine wall

63
Q

Structure of Placenta

What are lacunae?

A

Maternal blood pools via open ended arterioles into intervillous spaces within the placenta

64
Q

Structure of Placenta

What are the function of the chronic villi?

A

Extend into lacunae and mediate the exchange of materials between the foetus and the mother

65
Q

Structure of Placenta

What is the function of the umbilical cord?

A

Exchanged material is transported from the villi to the foetus, connects the foetus to the placenta

66
Q

Material Exchange of Placenta

How does material exhange occur in the placenta?

A

The chorionic villi extend into the intervillous space (lacuna) and exchange materials between the mother and foetus

67
Q

**Material Exchange of Placenta **

What are features that aid in the material exchange?

A

Chorionic villi are lined by microvilli to increase the available surface area for material exchange. Foetal capillaries within the chorionic villi lie close to the surface to minimise diffusion distance from blood in the lacunae

68
Q

Material Exchange of Placenta

What materials will diffuse from lacunae to faoetal capillaries?

A

Oxygen, nutrients, vitamins, antibodies and water

69
Q

Materila Exchange of Placenta

What materials will diffuse from lacuane into maternal blood vessels

A

Foetal waste (such as carbon dioxide, urea and hormones)

70
Q

**Hormonal Role of Placenta **

What hormones does the placenta produce?

A

Estrogen and progestrone

71
Q

**Hormonal Roles of Placenta **

What is the function of estrogen releases from placenta?

A

Estrogen stimulates the growth of uterine muscles (myometrium) and the development of the mammary glands

72
Q

Hormonal Roles of Placenta

What is the function of progesterone that is released from placenta?

A

Progesterone maintains the endometrium, as well as reducing uterine contractions and potential maternal immune responses

73
Q

Hormonal Roles of Placenta

What is the function of progesterone that is released from placenta?

A

Progesterone maintains the endometrium, as well as reducing uterine contractions and potential maternal immune responses

74
Q

Birth Process

What is positive feedback?

A

Involves a response that reinforces the change detected

75
Q

Birth Process

How does positive feedback used in the case of childbirth?

A

The detection of uterine wall stretching will lead to the release of oxytocin that induces uterine muscles to contract, reducing space in womb. This causes continous stretching until fetus is removed

76
Q

**Hormonal Control in Birth Process **

What are the chemical regulators of the birth process?

A

Oxytocin, estriol, progesterone and prostaglandin

77
Q

Hormonal Control in the Birth Process

How is estriol released?

A

Due to the stree induced resulting from stretches in uterine wall.

78
Q

Hormonal Control in Birth Process

What is the role of estriol?

A

Prepares the smooth muscle of the uterus for hormonal stimulation by increasing its sensitivity to oxytocin. Inhibits progesterone, which was preventing uterine contractions from occurring while the foetus developed

79
Q

Hormonal Control in Birth Process

When is oxytocin released by posterior pituitary?

A

When uterus is primed for childbirth

80
Q

Hormonal Control of Birth Process

What is the role of oxytocin?

A

Stimulates the uterine muscles to contract, initiating the birthing process

81
Q

Hormonal Control of Birth Process

When does the fetus release prostaglandins?

A

It responds to uterine contractions by releasing prostaglandins, which triggers further contractions

82
Q

Hormonal Control of Birth Process

When will the contractions stop?

A

When labour is complete and the baby is birthed

Biology Chapter 11 (4 decks)

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