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Zoology Semester 2 > APS136 1 > Flashcards

APS136 1 Flashcards

1
Q

Sex is not the same as…

A

reproduction

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2
Q

Reproduction is…

A

the production of offspring (either sexual or asexual)

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3
Q

Sex is…

A

the fusion of genetic material from two different parents during reproduction

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4
Q

A higher rate of reproduction can be achieved by reproducing …

A

asexually (cloning)

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5
Q

What are the advantages of asexual reproduction?

A

More efficient, easier, cheaper, relatively error-free

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6
Q

What are the disadvantages of asexual reproduction?

A

Any mutations also transmitted

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7
Q

What is fragmentation?

A

Parent body broken into pieces which then develop into adults - followed by regeneration (regrowth of lost body parts)

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8
Q

What is binary fission?

A

Single cell divides into 2 individual daughter cells

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9
Q

What is budding?

A

Offspring grows out of body of parent (specialised masses of cells released from parent that can develop into offspring)

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10
Q

What is parthenogenesis?

A

Virgin birth - unfertilised eggs develop into offspring but are not haploid (doesn’t occur in mammals due to genomic imprinting)

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11
Q

Parthenogenesis does not occur in mammals due to…

A

Genetic imprinting

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12
Q

What are the 4 main types of asexual reproduction?

A

Binary fission, fragmentation, budding, parthenogenesis

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13
Q

Some species reproduce both sexually and asexually, depending on…

A

environmental factors and stresses.
Low stress = asexual
High stress = sexual
e.g. aphids

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14
Q

Sexual reproduction has existed for…

A

1.5-2 billion years (life ~3.8bn)

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15
Q

Sexual reproduction involves…

A

meiosis, leading to recombination and segregation

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16
Q

recombination can … deleterious mutations and bring together … genetic combinations

A

Remove, novel

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17
Q

What are the 3 fundamental processes required for sexual reproduction?

A
  1. Gametogenesis - production of gametes
  2. Mating - transfer of gametes
  3. Fertilisation - fusion of gametes
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18
Q

Mating can be…

A

internal or external

requires males and females to synchronise

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19
Q

Broadcast spawning is an example of…

A

external fertilisation

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20
Q

What is required for external fertilisation?

A

Water - otherwise gametes would dry out

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21
Q

What are the problems with external fertilisation?

A

Can’t control delivery, requires huge numbers of gametes, predation of eggs is likely

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22
Q

internal fertilisation can be..

A

direct or indirect

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23
Q

What is direct internal fertilisation?

A

Sperm transferred directly into a female, often by an intromittent organ

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24
Q

What is indirect internal fertilisation?

A

Male deposits sperm ‘packet’ (spermatophore) and female picks it up
e.g. springtails

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25
Q

Hermaphrodites are individuals with…

A

both male and female reproductive parts - exchange sperm and use to fertilise own eggs
+ generally not self-fertilising

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26
Q

What are the 2 stages of gametogenesis?

A
  1. Meiosis - converting diploid cells into haploid cells

2. Spermatogenesis and oogenesis

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27
Q

Sperm are produced in the…

A

Seminiferous tubules (in the testes)

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28
Q

What transfers sperm to the penis?

A

Vas deferens

29
Q

Where is sperm stored?

A

Epididymis

30
Q

How much of semen is seminal fluids?

A

90%

31
Q

Sperm are produced from … … …

A

Spermatogonial stem cells

Primary spermatoctye (diploid) -> Secodary spermatocytes (diploid) -> spermatids (haploid) -> sperm (haploid)

32
Q

Each primary spermatocyte gives rise to … sperm cells

A

4

33
Q

In drosophila spermatogenesis occurs in..

A

cysts within the testes

  • from distal to proximal
  • starts in larval stage
  • sperm produced in a few days
34
Q

In humans spermatogenesis occurs in..

A

seminiferous tubules within testes

  • from periphery to lumen
  • starts in puberty
  • sperm produced in approx. 74 days
35
Q

In oogenesis, the primary oocyte undergoes meiosis 1 to form…

A

A secondary oocyte (diploid) and the first polar body, which contains far less cytoplasm

36
Q

In oogenesis, meiosis 2 forms…

A

2 more polar bodies (so 1 haploid ovum and 3 haploid polar bodies)

37
Q

Polar bodies…

A

are never fertilised - not enough resources

38
Q

At puberty, the hypothalamus secretes..

A

gonadotrophin-releasing hormone (GnRH)

39
Q

GnRH stimulates..

A

FSH (follicle stimulating hormone) and LH (lutenizing hormone) from the anterior pituitary cells.

40
Q

In spermatogenesis, FSH…

LH…

A
  • Stimulates development of seminiferous tubules (where sperm form) and spermatogenesis acting together with testosterone by stimulating Sertoli cells
  • Stimulates Leydig cells to secrete testosterone which stimulates spermatogenesis
41
Q

In oogenesis, FSH…

LH…

A
  • Stimulates development of follicles and secretion of estrogens
  • Stimulates maturation of follicles and release of ova at ovulation
42
Q

Estrogen…

A

enhances growth of follicles, grows endometrium

43
Q

Progesterone…

A

grows and maintains endometrium for pregnancy, secretes nutrients for embryo

44
Q

corpus luteum…

A

hormone secreting after ovulation

45
Q

Fertilisation is…

A

the union of (haploid) sperm and ovum (to produce a diploid zygote)

46
Q

What are the barriers faced during fertilisation?

A
  • Sperm must make it to the ovum
  • Gametes must recognise each other
  • Sperm must penetrate ovum
  • Haploid egg nucleus and sperm nucleus must fuse to form diploid zygote (syngamy)
  • Ovum must block entry of additional sperm (polyspermy) to avoid polyploidy
47
Q

What proportion of sperm survive to reach the ovum?

A

less than 1 in a million

48
Q

What are the features of a mammalian egg?

A
  • Germinal vesicle: nucleus containing DNA (nucleolus = germinal spot)
  • Ooplasm: cytoplasm containing nutrients
  • Vitelline membrane: Cell membrane surrounding ooplasm
  • Zona Pellucida: extracellular matrix containing glycoproteins
    Corona radiata: layer of follicle cells
49
Q

What are the main sections of a mammalian sperm cell?

A
  • Head: contains nucleus with sperm DNA, capped with acrosome, which penetrates the egg membrane using enzymes
  • Neck: contains the centriole (important for tail formation and movement, and development of embryo after fertilisation)
  • Midpiece (with central filamentous core): contains the mitochondria which provide energy for movement
  • Tail: drives the sperm forward
50
Q

Sperm can only move through…

A

liquid - terrestrial animals overcome this using seminal fluid (and oviductal fluid in female reproductive tract)

51
Q

External fertilisation almost always occur in … environments

A

aquatic

52
Q

Fertilisation requires sperm … of the egg coat

A

penetration

53
Q

In mammals, sperm penetrate the cumulus cell layer via … …, and sperm undergoes … reaction to penetrate the zona pellucida. Sperm and … plasma membranes … (mediated by sperm-egg recognition/attachment proteins). The sperm … (and certain other sperm components) enter the ovum. Membrane and ZP block to … is rapidly initiated.

A

hyperactivated motility, acrosome, oocyte, fuse, nucleus, polyspermy

54
Q

Polyspermy is … to mammals

A

pathological (and fatal)

55
Q

In sea urchins, eggs have a …

A

protective jelly coat

- contains proteins with strong, species-specific chemoattractant properties

56
Q

Under the sea urchin egg’s jelly coat is the egg plasma membrane, which is lined with … that hold … receptors. As the sperm release their acrosomal enzymes, a … develops from the sperm head (known as the … …), which reaches out to contact the egg’s surface. On the surface of the protrusion is a species-specific protein called …, which is detected by the ovum’s protein receptors. This is a highly effective barrier to interspecific fertilisation.

A

microvilli, protein, protrusion, acrosomal process, bindin

57
Q

In sea urchins, once membrane fusion has occured, the … … of the plasma membrane changes to prevent other sperm from fusing with the egg - different to in mammals (where … … change)

A

electrical potential, material properties

58
Q

Human egg coat protein … is in the top 5% most divergent molecules between humans and rodents, displaying the … diversification of reproductive molecules, particularly those involved in sperm-egg recognition.

A

ZP2, rapid

59
Q

…, found in abalone gastropods, is one of the fastest evolving metazoan proteins known, and is a sperm protein involved in…

A

Lysin, dissolving the egg envelope

60
Q

When it is about to be laid, the egg of a kiwi takes up around…

A

3/4 of the female’s body

61
Q

Across bird species, on average … of eggs fail to hatch

A

10-15%

62
Q

In kakapos, egg hatching failure rates can be over …

A

70%

- a reason as to why they are so endangered

63
Q

Why do eggs fail?

A

Fertilisation failure

  • failure of sperm to reach the egg
  • sperm or ovum dysfunction (may be linked to poor male/female quality)
  • Female anti-sperm response

Embryo death

  • Male factors (e.g. genetic)
  • Female factors
  • Male-female incompatibility (e.g. from inbreeding)
  • External factors
64
Q

What is the most intense site of selection for sperm?

A

The vagina - 0.0001% of sperm that enter get further than the vagina

65
Q

What are the characteristics of successful sperm?

A
  • motility is crucial (speed and direction)
66
Q

Once the sperm have got past the vagina…

A

muscular contraction actually help the sperm to reach the egg (even dead sperm reach the infundibulum when put past the vagina)

67
Q

What determines sperm motility?

A
  • morphology (long sperm have competitive advantage as they swim faster - long sperm males have higher paternity than short sperm males
68
Q

In birds, polyspermy is…

A

normal

69
Q

In birds, embryo survival is much higher…

A

if there is lots of sperm present in the egg (high polyspermy)

  • supernumerary sperm
  • potentially to help with ion transfer in such large eggs

Zoology Semester 2 (15 decks)

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