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BIOL 2312 > Chapter 49 - Reproduction > Flashcards

Chapter 49 - Reproduction Flashcards

1
Q

What is the difference between sexual and asexual reproduction?

A

asexual reproduction creates genetically identical offspring to the single parent. sexual reproduction creates genetically different offspring where male and female gametes come together

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2
Q

What is another name for asexual reproduction?

A

clonal reproduction

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3
Q

What are the 3 advantages of asexual reproduction?

A

1) Preserves genetic uniformity – advantageous in environments that remain stable and uniform
2) No energy expended in producing gametes
3) No energy expended in finding a mate, especially in sparsely populated areas or in sessile organisms

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4
Q

What type of environment does asexual reproduction usually occur in?

A

aqueous

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5
Q

What are the 3 different types of asexual reproduction?

A

fission, budding, fragmentation, parthenogenesis

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6
Q

What is fission? example?

A

the parent separates into two or more offspring of approximately equal size (e.g., planarians)

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7
Q

What is budding? example?

A

a new individual develops while attached to the parent (specialized region) – offspring may break free from the parent, or remain attached to form a colony (e.g., Hydra)

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8
Q

What is fragmentation? examples?

A

pieces separate from the body of a parent and develop (regenerate) into new individuals (e.g., flatworms, annelids, and some echinoderms)

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9
Q

What is pathogenesis? how does it work? offspring haploid or diploid?

A

no fertilization takes place, offspring can be haploid or diploid and are genetically different than the parent as the egg is still produced by meiosis

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10
Q

What are the advantages and disadvantages of sexual reproduction?

A

advantages: genetic diversity improves survival rate in a changing environment
disadvantages: use energy to create gametes and find mates

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11
Q

What are the 3 ways sexual reproduction creates genetic varaibility?

A

genetic recombination, independent assortment, and random fusion of gametes

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12
Q

What is the ultimate sources of variability for both sexual and asexual reproduction?

A

random DNA mutations

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13
Q

What is the formation of male and female gametes called?

A

gametogenesis

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14
Q

What is a zygote?

A

fusion of haploid sperm and egg

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15
Q

What are germ cells? location?

A

where gametes are formed, located in testes and ovaries

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16
Q

What do mitotic division of germ cells produce?

A

spermatogonia and oogonia

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17
Q

What does spermatogenesis produce?

A

4 mature haploid spermatozoa (sperm)

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18
Q

What is the structure of sperm?

A

motile cells driven through a watery medium by a flagellum

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19
Q

What is spermatid? what occurs here?

A

immature sperm, cytoplasm is lost – except for mitochondria, which produce the ATP that drive the flagellum this creates mature sperm

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20
Q

What is an acrosome?

A

A specialized secretory vesicle containing enzymes and other proteins that help the sperm penetrate the egg forms a cap over the nucleus in the head of the sperm

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21
Q

What does oogensis produce?

A

one mature, haploid ovum (egg) – a large cell containing most of the cytoplasm of the parent cell and 3 nonfunctional polar bodies

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22
Q

What stage does the oocytes in the ovary remain in?

A

1st prophase in meiosis

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23
Q

What stage are the oocytes in during ovulation?

A

2nd metaphase

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24
Q

When do oocytes complete meiosis?

A

fertilization

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25
Q

What type of nutrients does the egg store for different animals?

A

mammal eggs contain little nutrients. Eggs of birds and reptiles contain all nutrients required for complete embryonic development

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26
Q

What is the purpose of the egg coat?

A

protect the egg from injury and infection and, in some species, protect the embryo after fertilization

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27
Q

How does external fertilization occur? what type of animals?

A

Males and females synchronize release of large quantities of eggs and sperm into the surrounding water. occurs in most aquatic invertebrates, bony fishes, and amphibians

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28
Q

How does internal fertilization occur? what type of animals?

A

Sperm are released close to or inside the entrance of the female’s reproductive tract. Internal fertilization provides the aquatic medium required for fertilization inside the female’s body. Occurs in reptiles, birds, mammals annelids, and some arthropods, mollusks, and fishes

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29
Q

What happens a sperm touches the outer surface of an egg?

A

receptor proteins in the sperm plasma membrane bind the sperm to the vitelline coat or zona pellucida

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30
Q

Are sperm from any species allowed to bind to any egg?

A

mostly no, only a sperm from the same species as the egg can recognize and bind to the egg surface

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31
Q

What is the acrosomal reaction? when does this happen?

A

Attachment of sperm to egg triggers the acrosomal reaction – enzymes in the acrosome are released from the sperm and digest a path through the egg coats
The sperm follows the path until its plasma membrane touches and fuses with the plasma membrane of the egg

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32
Q

What is the fast block to polyspermy? how fast does this occur? what animals does this occur?

A

Fusion of egg and sperm opens ion channels in the plasma membrane of the egg, spreading a wave of electrical depolarization over the egg surface
Depolarization alters the egg plasma membrane’s potential from negative to positive so that it cannot fuse with any additional sperm – eliminating the possibility that more than one set of paternal chromosomes enters the egg

occurs within a few seconds after fertilization, invertebrates

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33
Q

What is the slow block to polyspermy? how fast does this occur?

A
  • Fusion of egg and sperm triggers release of Ca2+ ions from the egg’s ER into the cytosol
  • Ca2+ ions activate control proteins and enzymes that initiate intense metabolic activity in the fertilized egg
  • Ca2+ ions trigger the cortical reaction – cortical granules under the egg’s plasma membrane release their contents by exocytosis
  • Enzymes released from cortical granules alter the egg coats so no further sperm can penetrate to the egg

occurs within minutes after fertilization

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34
Q

What happens when the sperm nucleus enters the egg cytoplasm?

A

microtubules move the sperm and egg nuclei together in the egg cytoplasm and they fuse

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35
Q

What is oviaparous?

A

animals lay eggs that contain nutrients needed for development of the embryo outside the mother’s body

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36
Q

What is ovoviviparous?

A

animals retain fertilized eggs within the body and the embryo develops in the egg – there is no uterus – eggs hatch inside the mother and offspring are released

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37
Q

What is vivparous?

A

animals retain the embryo within the mother’s uterus and nourish it during at least early development

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38
Q

What are eutherians?

A

placental mammals

39
Q

What are metatherians? how does this work?

A

marsupials, provide nutrients to the embryo during early stages of development via an attached membranous sac containing yolk – the embryo is born at an early stage and crawls to an abdominal pouch (marsupium) where it attaches to a nipple and continues development

40
Q

What is hermaphroditism?

A

both mature egg producing and mature sperm producing tissues are present in the same individual

41
Q

Does most hermaphroditic animals fertilizes themselves? what mechanisms does they use?

A

no, self fertilization is prevented by anatomical barriers, or by producing mature egg and sperm at different times

42
Q

What is the difference between Simultaneous hermaphrodites and sequential hermaphrodites

A

Simultaneous hermaphrodites develop functional ovaries and testes at the same time – sequential hermaphrodites change from one sex to the other

43
Q

Where are eggs fertilized? where do they implant?

A

Eggs are fertilized in the oviduct and implant in the uterus lining (endometrium)

44
Q

What is the greater vestibular glands?

A

secrete lubricating fluid in human females

45
Q

What type of control is the female reproduction system under? what are the main organs? (4)

A

neuroendocrine control

main organs: hypothalamus, pituitary, ovaries, and uterus

46
Q

What is the average ovarian cycle length?

A

28 days

47
Q

What happens in the first part of the ovarian cycle?

A

increase in gonadotropin- releasing hormone (GnRH) released by the hypothalamus. GnRH stimulates the pituitary to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

48
Q

How many primary oocytes does FSH stimulate to be released from prophase of meiosis I and continue meiosis?

A

6 to 20

49
Q

When do secondary oocytes occur?

A

when primary oocytes arrest in metaphase II

50
Q

What forms a follicle?

A

secondary oocyte surrounded by cells

51
Q

How does the follicle develop?

A

As the follicle enlarges, FSH and LH interact to stimulate the follicular cells to secrete estrogens, primarily estradiol

52
Q

What effects do estrogens have?

A

Secreted in low amounts, estrogens have a negative feedback effect on the pituitary, inhibiting its secretion of FSH

High estrogen level has a positive feedback effect on the hypothalamus and pituitary, increasing release of GnRH and stimulating the pituitary to release a burst of FSH and LH

53
Q

How do the levels of estrogen change over the ovarian cycle?

A

Estrogen secretion increases steadily, and its level peaks at about 12 days after follicle development begins

54
Q

What hormones influence ovualtion?

A

The burst in LH secretion stimulates follicle cells to release enzymes that digest the wall of the follicle, causing it to burst and release the egg (ovulation)

55
Q

How many oocytes does each ovary contain at birth? stage of development?

A

around 1 million, arrested at the end of the first meiotic prophase

56
Q

How many oocytes survive till female is sexually mature?

A

200,000 - 400,000

57
Q

How many oocytes are ovulated in a female’s lifetime?

A

400

58
Q

How do eggs travel after ovulation?

A

The egg is pulled into the oviduct by the current produced by the beating of cilia lining the oviduct

59
Q

What is the luteal phase and what hormones are involved?

A

last stage of menstrual cycle initiated by LH

60
Q

What is the corpus luteum?

A

LH causes the follicle cells remaining at the surface of the ovary to grow into a corpus luteum, which secretes estrogens, large quantities of progesterone, and inhibin

If fertilization does not occur, the corpus luteum gradually degenerates and its cells are phagocytized – in the absence of progesterone, menstruation begins

61
Q

What does progesterone do?

A

stimulates growth of the uterine lining and inhibits contractions of the uterus – it also inhibits secretion of GnRH, which inhibits release of FSH and LH

62
Q

What is menstrual flow the result of? length? hormones involved?

A

Menstrual flow results from the breakdown of the thickened endometrium – when flow ceases (day 4 􏰁 5 of the cycle)

progesterone stops blood supply

63
Q

When does the endometrium begin to grow again?

A

proliferative phase right after menstruation

64
Q

What happens to the uterine lining if fertilization does not take place after ovulation? what phase is this?

A

does not take place, the uterine lining continues to grow for another 14 days (the secretory phase)

65
Q

Where are testes suspended in? purpose?

A

Testes are suspended in the scrotum, which keeps them cooler than the body core

66
Q

Pathway of sperm?

A
  • -Mature sperm flow from the seminiferous tubules into the epididymis, a coiled storage tubule-attached to the surface of each testis
  • -Rhythmic muscular contractions of the epididymis move sperm into the vas deferens, which leads into the urethra
67
Q

Where are sperm produced? how long does this take?

A

Sperm are produced in seminiferous tubules – the entire process, from spermatogonium to sperm, takes 9 to 10 weeks

68
Q

How much sperm is produced a day?

A

around 130 million

69
Q

What are sertoli cells? hormones involved?

A

surround developing spermatocytes in the seminiferous tubules – they supply nutrients and seal spermatocytes off from the body’s blood supply

stimulated by FSH

70
Q

What are leydig cells? hormones involved?

A

located in the tissue surrounding the developing spermatocytes produce male sex hormones (androgens), particularly testosterone

stimulated by LH

71
Q

What does seminal vesicles secrete?

A

thick seminal fluid containing prostaglandins into the vasa deferentia

72
Q

Location and function of prostate gland?

A

surroundstheregion where the vasa deferentia join the urethra, adds an alkaline secretion that raises semen pH and activates motility of the sperm

73
Q

What does the bulbourethral glands secrete? function?

A

secretes a clear, mucus-rich fluid into the urethra which lubricates the tip of the penis and neutralizes the acidity of residual urine in the urethra

74
Q

What percentage of sperm is in semen?

A

less than 5%

75
Q

When can a human egg be fertilized?

A

only while it is in the third of the oviduct nearest the ovary

76
Q

Advantage of more than one sperm trying to fertilize egg?

A

Although only one sperm fertilizes the egg, the combined release of acrosomal enzymes from many sperm greatly increases the chance of penetrating the zona pellucida

77
Q

When does the embryo implant in the uterus?

A

around 7 days after ovulation

78
Q

What hormones are involved in implantation? function?

A

During and after implantation, cells associated with the embryo secrete human chorionic gonadotropin (hCG), which keeps the corpus luteum from breaking down

79
Q

What takes over the secretion of progesterone around 10 weeks after implantation? what happens to the corpus luteum?

A

placenta, the hCG levels drop and corpus luteum regresses but continues to secrete the hormone relaxin

80
Q

What is the function of relaxin?

A

inhibits contraction of the uterus until the time of birth

81
Q

What is infertility defined as?

A

inability of the female to get pregnant after 12 months of frequent, contraceptive􏰁free intercourse

82
Q

What are some causes of male infertility?

A

low sperm concentration or motility, erectile dysfunction or duct blockage, or health and lifestyle issues

83
Q

What are some causes of female infertility?

A

inflammation of the Fallopian tubes, hormone deficiencies, or various environmental factors – athletes may experience athletic menstrual cycle irregularities

84
Q

What are the 3 techniques for contraception?

A
  • Preventing fertilization
  • Preventing ovulation
  • Interfering with implantation if fertilization does occur
85
Q

What is the rhythm method?

A

avoiding intercourse during the time of the month when the egg can be fertilized

86
Q

What can latex condoms prevent?

A

disease transmission

87
Q

What is a diaphragm?

A

used with spermicidal jelly blocks the cervix in females

88
Q

What are surgical preventions to fertilization?

A

vasectomy and tubal ligation

89
Q

What are the 2 types of oral contraceptives?

A

combination of estrogen and progestin, or progestin alone

90
Q

How does the the pill work?

A

inhibiting secretion of FSH and LH by the pituitary – without these hormones, ovulation does not occur

91
Q

Side effects for women who smoke and take the pill?

A

increased risk of heart attacks and strokes

92
Q

When does the morning-after pill work?

A

72 hours after intercourse

93
Q

What does Mifepristone (RU-486) do?

A

blocks progesterone receptors in the uterine lining – this initiates a menstrual period, removing any embryo that may have implanted

94
Q

What timeframe is Mifepristone (RU-486) approved for in the US?

A

up to 49 days post-conception, only available by prescription

BIOL 2312 (14 decks)

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