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Biol225 > chapter 46 animal reproduction > Flashcards

chapter 46 animal reproduction Flashcards

1
Q

sexual reproduction

A

creation of offspring by fusion of male and female gamete

-forms zygote

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2
Q

asexual reproduction

A

creation of offspring without the fusion of gametes

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3
Q

fertilization depends on

A

mechanisms that bring together gametes of the same species

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4
Q

Regulation of mammalian reproduction done by

A

interplay of tropic and sex hormones

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5
Q

who produces and transports gametes

A

reproductive organs

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6
Q

in placental mammals

A

embryo develops fully within mothers uterus

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7
Q

asexual reproduction

A
  • budding
  • fragmentation (breaking of body into pieces)
  • parthenogenesis (development of offspring from unfertilized egg–mostly invertebrates)
  • most advantageous in stable, favourable environments
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8
Q

sexual reproduction

A
  • variance in phenotypes (recombination and gene shuffling)

- enhance reproductive success of parents when environmental factors change relatively rapidly

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9
Q

Reproductive cycles

A
  • most animals exhibit cycles related to changing seasons
  • controlled by hormones and environmental cues
  • ovulation
  • some can reproduce both sexually and asexually
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10
Q

ovulation

A

is the release of mature eggs at midpoint of a female reproductive cycle

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11
Q

effects of global warming on reproduction

A

since seasonal temperature is important cue, climate change can decrease reproductive success

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12
Q

variation in patterns of sexual reproduction

A
  • finding a mate for sexual reproduction can be difficult
  • solution: hermaphroditism (an individual has both sex organs)
  • some animals, sex is environmentally determined and can change
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13
Q

Fertilization (2 types)

A
  1. External fertilization

2. Internal fertilization

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14
Q
  1. external fertilization
A

eggs shed by the female and are fertilized by sperm in external environment.

  • Huge numbers of gametes
  • low survival rate
  • moist environment required
  • spawning can occur (all cluster at same time and release gametes)
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15
Q
  1. Internal fertilization
A
  • sperm deposited in/near female reproductive tract, where fertilization occurs
  • requires behavioural interactions and compatible copulatory organs
  • production of fewer gametes
  • higher rate of survival
  • parental care and protection of embryos
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16
Q

all fertilization requires

A
  • critical timing (often mediated by environmental cues)
  • pheromones
  • courtship and/or behaviour
17
Q

to reproduce sexually

A
  • animals must produce gametes (most made by gonads)
  • some simple systems don’t have gonads (gametes form from undifferentiated tissue)
  • some have sets of accessory tubes/glands that carry, nourish and protect gametes+developing embryos
18
Q

most Insects have…

A
  • separate sexes w/ complex reproductive systems

- in many, female has spermatheca

19
Q

spermatheca

A

in some insects, where sperm is stored during copulation

20
Q

gametogenesis

A

production of gametes, differs in male and female

-distinct structure and function of different sexes reflect the differences

21
Q

Endocrine glands responsible for human reproduction

A
  • hypothalamus (GnRH) stimulates release of (FSH and LH) from anterior pituitary
  • (FSH ann LH regulate processes in the gonads and production of sex hormones) gonads
22
Q

sex hormones

A

main sex hormones are steroid hormones

  • testosterone (main androgen)
  • estrogens (consist of mainly estradiol and progesterone)
23
Q

sex hormone functions

A
  • gamete production
  • promote sexual behaviour
  • stimulate development of primary and secondary sex characteristics
24
Q

Menstrual cycles

A

characteristic of only humans and some primates

  • endometrium is shed from uterus (menstruation)
  • sexual receptivity not limited to a timeframe
25
Q

Estrous cycles

A

characteristic of most mammals

  • endometrium is reabsorbed by the uterus
  • sexual receptivity limited to a “heat” period (estrus)
  • length and frequency vary from species to species
26
Q

Embryonic development main steps (3)

A
  1. Conception
  2. Embryonic development
  3. birth
27
Q

Embryonic development

A
  1. Fertilization (sperm+egg=zygote)
  2. Cleavage (blastula)
  3. Gastrulation (gastrula)
  4. Organogenesis (tail-bud embryo)
    * some: metamorphosis (larval stages)
28
Q

Fertilization (embryonic development)

A

the formation of a diploid zygote from haploid egg and sperm

29
Q

Fertilization (part 2)

A
  • sperm penetrate the protective layer around the egg
  • receptors on the egg surface bind to molecules on the sperm surface
  • changes at the egg surface prevent polyspermy (entry of multiple sperm nuclei into egg)
30
Q

Acrosomal reaction

A
  • triggered when sperm meets egg
  • acrosome (on tip of sperm) releases hydrolytic enzymes that digest material surrounding egg
  • gamete contact (and/or) fusion depolarizes the egg cell membrane, sets up a block to polyspermy
31
Q

cortical reaction

A
  • fusion of egg and sperm also initiates this run
  • vesicles sebaceous in egg plasma membrane release contacts and form a fertilization envelope (acts as slow block to polyspermy)
  • requires a high [Ca2+] ions in the egg
  • rxn triggered by change in [Ca2+]
  • Ca2+ spread across the egg correlates with appearance of fertilization envelope.
32
Q

Egg activation

A
  • rise in cytosolic Ca2+ increases rates of cellular respiration and protein synthesis by egg
  • with these rapid changes in metabolism, the egg is “activated”
  • proteins and mRNAs needed for activation already present in egg
  • sperm nucleus merges with the egg nucleus
  • cell division begins*
33
Q

Fertilization in mammals

A
  • internal
  • zona pellucida (where sperm binds to a receptor) changes, ensure one sperm enters egg
  • first cell division occurs 12-36 hours after sperm binding
  • diploid nucleus forms after first division of zygote
34
Q

cleavage

A

(after fertilization)

  • period of rapid cell division, without growth
  • partitions the cytoplasm of one large cell into many smaller cells (blastomeres)
  • blastula forms
35
Q

blastula

A
  • during cleavage

- ball of cells with a fluid-filled cavity (called blastocoel)

36
Q

Three germ layers

A
  1. Endoderm
  2. Mesoderm
  3. Ectoderm
37
Q
  1. Endoderm
A

epithelial lining of

  • digestive tract, liver and pancreas
  • respiratory tract
  • excretory
  • reproductive tracts and ducts
  • thymus, thyroid and parathyroid glands
38
Q
  1. Mesoderm
A
  • skeletal and muscular systems
  • circulatory and lymphatic systems
  • excretory and reproductive systems (except germ cells)
  • dermis of skin
  • adrenal cortex
39
Q
  1. Ectoderm
A
  • epidermis of skin, sweat glands and follicles
  • nervous systems
  • pituitary gland, adrenal medulla
  • jaws and teeth
  • germ cells

Biol225 (7 decks)

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