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BIOLOGY 1030 > Animal Reproduction and Development > Flashcards

Animal Reproduction and Development Flashcards

1
Q

Compare sexual and asexual reproduction.

A

. In sexual reproduction, the fusion of haploid gametes forms a diploid cell, the zygote. The animal that develops from a zygote can in turn give rise to gametes by meiosis The female gamete, the egg, is a large, nonmotile cell. The male gamete, the sperm, is generally a much smaller, motile cell.

Asexual reproduction is the generation of new individuals without the fusion of egg and sperm. In most asexual animals, reproduction relies entirely on mitotic cell division.

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2
Q

Contrast monoecious and dioecious species.

A

monoecious:
having both the male & female reproductive organs in the same individual; hermaphrodite.
EX: porifera, flatworms, annelids etc.

dioecious:
having the male & female reproductive parts on different individuals of the same species
EX: brachiopods (reproduce sexually), nematoda, arthropods etc.

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3
Q

Diagram a typical animal life cycle including all stages and processes.

A
  1. Fertilization (zygote)
  2. Cleavage (zygote to blastula)
  3. Gastrulation (gastrula)
  4. Organogenesis (tail bud embryo)
  5. metamorphosis in some animals
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4
Q

How does spermatogenesis differ from oogenesis?

A

Only in spermatogenesis do all four products of meiosis develop into mature gametes
In oogenesis, cytokinesis during meiosis is unequal, with almost all the cytoplasm segregated to a single daughter cell. This large cell is destined to become the egg; the other products of meiosis, smaller cells called polar bodies, degenerate.

Spermatogenesis occurs throughout adolescence and adulthood. During oogenesis in human females, mitotic divisions are thought to be complete before birth, and the production of mature gametes ceases at about age 50.

Spermatogenesis produces mature sperm from precursor cells in a continuous sequence, whereas oogenesis has long interruptions.

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5
Q

Describe the general structure of animal gametes.

A

i

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6
Q

Contrast external and internal fertilization.

A

in species with external fertilization, the female releases eggs into the environment, where the male then fertilizes them.

Other species have internal fertilization: Sperm are deposited in or near the female reproductive tract, and fertilization occurs within the tract.

A moist habitat is almost always required for external fertilization, both to prevent the gametes from drying out and to allow the sperm to swim to the eggs. Many aquatic invertebrates simply shed their eggs and sperm into the surroundings, and fertilization occurs without the parents making physical contact.
When external fertilization is not synchronous across a population, individuals may exhibit specific mating behaviours leading to the fertilization of the eggs of one female by one male Such “courtship” behaviour has two important benefits: It allows mate choice and, by triggering the release of both sperm and eggs, increases the probability of successful fertilization.

Internal fertilization is an adaptation that enables sperm to reach an egg efficiently, even when the environment is dry. It typically requires cooperative behaviour that leads to copulation, as well as sophisticated and compatible reproductive systems. The male copulatory organ delivers sperm, and the female reproductive tract often has receptacles for storage and delivery of sperm to mature eggs.

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7
Q

Compare oviparity, ovoviviparity and viviparity.

9. Explain the advantages and disadvantages of each.

A

Oviparity (egg bearing) is when the embryo is in an egg in the open environment when it is developing.
- It is beneficial to parents because they don’t need to stay with their eggs (although some do) and they can possibly have separate food needs after the child is born or if they have the same food needs, can live separately so they do not compete.
disadvantage- young are less likely to survive predator attacks, deadly temperature changes, and other environmental issues that may arise.

Ovoviviparity (offspring develops in mother’s body but is surrounded by a yolk)

  • is good because the embryo develops from yolk for its nutrients and DOES NOT DEPEND on the mother so it takes less energy than viviparity to grow the young. But there is still temperature regulation that keeps the young in a better environment.
  • The drawback is the trade off of producing more young.

Viviparity (give birth to live young)

  • is good because the embryo can develop inside the mother WHERE TEMPERATURES and NUTRIENTS ARE STABLE, thus enabling the young a greater chance to survive. This is especially true in cold weather.
  • The disadvantage is that it TAKES MORE ENERGY for the mother and thus cant produce as many young in her life.
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8
Q

Describe the events of cell division (from 1020) during the cleavage stage.

A

i

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9
Q

Describe the major events that occur during gastrulation.

A
  1. 1st few divisions in cleavage occur in the fallopian tubes as the cell is actually heading to the uterus (where it embeds), the sperm finds its way up there & fertilizes
    - will bind to UTERINE LINING (ENDOMETRIAL EPITHELIUM)
    the inner cell mass what will become the embryo basically
    - trophoblast basically will become the placenta, it will bind to uterine lining, invade the uterine lining, find blood vessels within the uterus & become the placenta as the embryo is developing
  2. trophoblast is expanding into the uterine tissue finding blood vessels & eventually completely interwinds with blood vessels making an exchange system
    - another countercurrent exchange system where gases & various nutrients & things will pass back & forth b/t the maternal blood & the new blood vessels that will eventually head out that direction to the placenta from the embryo/fetus actually
    - inner cell mass divides into the epiblast & hypoblast & the epiblast will become most of the embryo
  3. following implantation, the trophoblast continues to expand into the endometrium, & 4 new membranes appear: allantois, aminon, chorion, & yolk sac
    - although these extraembryonic membranes are formed by the embryo, they enclose specialized structures located outside the embryo
    - as implantation is completed, gastrulation begins
    - cells move inward from the epiblast through a primitive steak & form mesoderm & endoderm, just as in the chick
  4. eventually gastrulation occurs, epiblast, there is a primitive steak & cells will flow in from the outside & form the endoderm & the mesoderm & cell division resumes, there is a yolk (small & gets smaller & smaller) b/c placenta will feed embryo
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10
Q

Sexual reproduction

A

a type of reproduction in which 2 parents give rise to offspring that have unique combinations of genes inherited from both parents via the gametes

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11
Q

Asexual reproduction

A

the generation of offspring from a single parent that occurs without the fusion of gametes
- in most cases, the offspring are genetically identical to the parent

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12
Q

Parthenogenesis

A

a form of asexual reproduction in which females produce offspring from unfertilized eggs

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13
Q

Dioecious

A

having the male & female reproductive parts on different individuals of the same species

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14
Q

Monoecious

A

having both the male & female reproductive organs in the same individual; hermaphrodite

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15
Q

Hermaphrodite

A

an individual that functions as both male & female in sexual reproduction by producing both sperm & eggs

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16
Q

Protandry

A

state in hermaphroditic systems that is characterized by the development of male organs or maturation of their products before the appearance of the corresponding female product thus inhibiting self-fertilization and that is encountered commonly in mints, legumes, and composites and among diverse groups of invertebrate animals

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17
Q

Protogyny

A

state in hermaphroditic systems that is characterized by development of female organs or maturation of their products before the appearance of the corresponding male product thus inhibiting self-fertilization and that is encountered in apples, pears, figworts, and among several groups of invertebrate animals

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18
Q

Gametogenesis

A

the process by which gametes are produced

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19
Q

Spermatogenesis

A

the continuous & prolific production of mature sperm cells in the testis

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20
Q

Oogenesis

A

the process in the ovary that results in the production of female gametes

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21
Q

Isolecithal

A

sparse evenly distributed yolk, eg., sea urchin, mouse.

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22
Q

Mesolecithal

A

moderate amount of yolk, often unevenly distributed, eg., frog.

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23
Q

Telolecithal

A

dense yolk concentrated at one end, eg., bird, reptile.

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24
Q

Fertilization

A

the fusion of egg & sperm, The moment the sperm penetrates (sticks head into) the egg (this event marks the beginning of fertilization)
The fusion of the egg nucleus and the sperm nucleus occurs later during fertilization

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25
Q

Spermatophore

A

or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especially salamanders and arthropods, and transferred in entirety to the female’s ovipore during reproduction

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26
Q

Copulatory organ

A

An organ utilized by the male animal for insemination, that is, to deposit spermatozoa directly into the female reproductive tract

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27
Q

Acrosome

A

front part of the sperm cell which releases contains a bunch of enzymes and releases and breaks the barrier allowing the sperm to reach cell membrane of the egg

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28
Q

Polyspermy

A

Immediately after egg and sperm fuse, egg undergoes changes to prevent polyspermy
Prevent multiple sperm to enter the egg
Because if you have more than one sperm entering you have to many chromosomes
Trisomy- one from egg and 2 from 2 different sperms (3 sets of chromosomes)

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29
Q

Cleavage

A

The first cell division marks the end of fertilization.

Species undergo either holoblastic (complete) or meroblastic (incomplete) cleavage

30
Q

Organogenesis

A

the last major stage of embryonic development, local changes in cell shape and large-scale changes in cell location generate the rudimentary organs from which adult structures grow.

31
Q

mitosis

A

Regular cell division for growth and development
DNA is duplicated before the cell divides
Result in 2 daughter cells with the same number of chromosomes as the parent cell
Ie. 2 diploid cells (2n) with identical DNA

32
Q

Meiosis

A

Cell division for sexual reproduction (gamete production)
DNA is duplicated then the cell divides ‘then the daughter cell also divides
Results in 4 cells with half the number of chromosomes
Ie. 4 haploid gametes (n) with shuffled DNA

33
Q

What are the types of asexual reproduction

A

budding
fission
fragmentation
parthenogenesis

34
Q

Explain the advantages and disadvantages of both types of reproduction

A

By producing offspring of varied genotypes, sexual reproduction may enhance the reproductive success of parents when environmental factors, such as pathogens, change relatively rapidly
In contrast, asexual reproduction is expected to be most advantageous in stable, favourable environments because it perpetuates successful genotypes faithfully and precisely.

unique combinations of parental genes formed during meiotic recombination & fertilization

  1. beneficial gene combinations arising through recombination might speed up adaptation. Although this idea appears straightforward, the theoretical advantage is significant only when the rate of beneficial mutations is high and population size is small
  2. the shuffling of genes during sexual reproduction might allow a population to rid itself of sets of harmful genes more readily.
35
Q

Fragmentation

A

(platyhelminthes)
Results in genetic clone
Also cnidaria annelids porifors tunicates
Segments break off and they grow into new worms (pieces of parent no)
an individual (single parent) may break into many small pieces, each of which regenerates into a fully functional individual

36
Q

Budding

A

(cnidaria)- ex- hydra
Results in genetic clone
Cnidarians also reproduce sexually
a large parent produces outgrowths that enlarge and eventually separate from the main body

37
Q

Parthenogenesis

A

eg. In Hymenoptera- bees ants wasps)
Results in genetic clone
Occurs in all Hymenoptrea (bees ants and wasps)
Looks like sexual reproduction but no sex
females produce offspring from unfertilized eggs
uses the reproductive tract of the female.
The progeny can be either haploid or diploid. If haploid, the offspring develop into adults that produce eggs or sperm without meiosis.

38
Q

Explain hermaphroditism

A

hermaphroditism, in which each individual has both male and female reproductive systems
Because each hermaphrodite reproduces as both a male and a female, any two individuals can mate. Each animal donates and receives sperm during mating,both go away pregnant and lay eggs)
in some species hermaphrodites are also capable of self-fertilization, allowing a form of sexual reproduction that doesn’t require any partner or they can be fertilized by another male
ex- such as barnacles; burrowing animals, such as clams; and some parasites, including tapeworms

39
Q

spermatogenesis

A

meiosis happens continually in adult male humans… hundreds of millions of new sperm per day
Takes 7 weeks to develop in seminiferous tubules (with help of Sertoli cells, or “nurse cells”)
after maturation, exits seminiferous tubules via lumen takes 3 weeks to travel through epididymis(grows a tail)

Have flagellum (we have very few) where the flagellum connects to main part of the body has many mitochondria and they take sugar from nearby mainly fructose and make ATP to power the flagellum rest is nucleus  (don't have typical organelles of most animals) 
all they contribute is nucleus when the penetrate cells (lots of DNA)

each spermatocyte gives rise to 4 spermatids through meiotic division

40
Q

oogenesis

A

All prophase I happens prior to birth – then meiosis halts until puberty
Once a month, one primary oocyte (within a follicle) completes meiosis I
Meiosis II halts at metaphase – secondary oocyte awaits penetration by sperm
Then meiosis II completes resulting in a mature egg (with the head of a sperm cell already within)
Polar bodies are thrown out

41
Q

Describe reproduction in hymenoptera

A

Sexual reproduction in (Diploid egg) Hymenoptera results in females always
Through parthenogenesis an unfertilized egg that remains haploid becomes male (only have single parent mother so only one pair of chromosomes

very rare case of parthenogenesis where chromosomes duplicate and haploid egg becomes female

42
Q

Explain some ways of sexual reproduction

A

Paired hermaphrodites (molluscs leeches snails slugs)
Individuals that have both male and female reproductive organs that pair with another hermaphrodite
Male part of on impregnates other (both go away pregnant and lay eggs)
Lone hermaphrodites (c elegans) (although can mate in pairs)
Have both egg and sperm
Can lay eggs on its own or by male

43
Q

Embryology

A

early neurodevelopment

Development of nervous systems

44
Q

Development is…

A

is a lifelong process
In humans most of it occurs before birth but continues through lifetime
New brain cells gut cells

45
Q

Describe the mechanisms that prevent multiple sperm from fusing with a single egg.

A

polyspermy

fast and slow

46
Q

gametogenesis

A

process by which gametes are produced

47
Q

a. Identify examples for each.

A 
sexual:
ex:
- humans
- cnidarians (medusa)
- echinoderms
- chordates
- playhelminthes
- molluscs
- annelids (hermaphroditic)
- brachiopoda
- nematodes
- arthropods
asexual:
ex:
- cnidaria (polyps)
- hydra
- platyhelminthes (hermaphroditic)
- annelids (fragmentation)
- poriforea
- tunicates
- hymenoptera - bees, ants, wasps
- echinoderms
- chordates(parthenogenesis)
- arthropods (parthenogenesis)
48
Q

Describe the general overview of fertilization

A
  1. sperm dissolve or penetrate any protective layer surrounding the egg to reach the plasma membrane.
  2. molecules on the sperm surface bind to receptors on the egg surface, helping ensure that a sperm of the same species fertilizes the egg
  3. changes at the surface of the egg prevent polyspermy, the entry of multiple sperm nuclei into the egg.
49
Q

Explain Fertilization in sea urchins

A
  1. Contact- the sperm contacts eggs jelly coat
  2. Acrosomal reaction: enzymes released from acrosome to digest egg’s jelly coat (make a hole in coat)
    Acrosomal process extends to bind to receptor molecules on egg’s surface (conspecific recognition)

3.Contact and fusion of egg and sperm- membranes fuse
Sperm nucleus enters egg cytoplasm , triggers
Fast polyspermy block (not evident in mammals,only in sea urchins), Immediately after penetration, egg depolarizes
This prevents other sperm from entering the cell

  1. Slow polyspermy block (“cortical reaction”)(changing the cortex of the egg)
    Cortical granules (vesicles) fuse with membrane
    Release particles
    Vitelline layer pushed away from membrane
    Cortical granules push them far away so that no new sperm cells can enter because the barrier is to thick/ far away
    Vitelline layer hardens into fertilization envelope
    Prevents penetration of additional sperm
    Egg activation occurs
    Sudden increase in metabolic activity getting egg ready for cleavage
    Otherwise, it is dormant
50
Q

Fertilization in mammals

A

Essentially same story as in sea urchins, except
Sperm also must pass through follicle cells
When the follicle bursts when egg is being released a bunch of follicle cells surround the egg and stay surrounded around the egg
Jelly coat is called zona pellucida
Different proteins different make up than sea urchins but are functionally the same
No fast block to polyspermy
Fertilization much slower (often > 24 h) compared to 90 min in sea urchins
Can take up a day to a half or 2 days
Fertilization is from penetration of sperm cell to all of egg activation and metabolic activity that has to occur up until the very first cell division

51
Q

Fertilization in mammals

A

Essentially same story as in sea urchins, except

Sperm also must pass through follicle cells
When the follicle bursts when egg is being released a bunch of follicle cells surround the egg and stay surrounded around the egg
Jelly coat is called zona pellucida
Different proteins different make up than sea urchins but are functionally the same
There the binding of a sperm to a sperm receptor induces an acrosomal reaction, facilitating sperm entry sperm binding triggers a cortical reaction, the release of enzymes from cortical granules to the outside of the cell. These enzymes catalyze changes in the zona pellucida, which then functions as the slow block to polyspermy
No fast block to polyspermy
Fertilization much slower (often > 24 h) compared to 90 min in sea urchins
Can take up a day to a half or 2 days
Fertilization is from penetration of sperm cell to all of egg activation and metabolic activity that has to occur up until the very first cell division

52
Q

Depolarization

A

resting membrane potential (sodium channels open sodium is positively charged and relatively low amounts are present in the cell so it floods in raising the voltage compared to the outside and this change in voltage prevents other sperm from entering the egg)

53
Q

fast block to polyspermy

A

The depolarization of the egg plasma membrane that begins within 1–3 seconds after a sperm binds to an egg membrane protein. The depolarization lasts about 1 minute and prevents additional sperm from fusing with the egg during that time.

54
Q

fast block to polyspermy

A

The depolarization of the egg plasma membrane that begins within 1–3 seconds after a sperm binds to an egg membrane protein
lasts about 1 minute and prevents additional sperm from fusing with the egg during that time.
not evident in mammals,

55
Q

conspecific recognition

A

Surface proteins on egg membrane that bind to the sperm cells, this is important in sea urchins because the gametes just float around so there needs to be something to identify if the match
If they match, they can enter (egg and sperm are from same species)

“lock-and-key” recognition is especially important for sea urchins and other species with external fertilization because the surrounding water may contain gametes of other species.

56
Q

Holoblastic cleavage

A

(complete)
Each cell divides completely each time
Sparse yolk(food/energy storage) left in each cell
In some species all cells have same amount of yolk other species have varying in each cell

57
Q

What are the types of holoblastic cleavage?

A
  1. Bilateral
  2. Radial(echinoderms amphibians lamprey)
  3. Rotational(we do mammals, placental and marsupials)
  4. Spiral
    Placental mammals only have small amount of yolk because it only needs to feed embryo long enough to be implanted into uterus then it gets fed by placenta
58
Q

Meroblastic cleavage

A

incomplete cleavage)
Large amount of yolk
Cleavage cant occur because of this
Cytokinesis Cant split all of the yolk up into 2
One end where there’s not much yolk, divides the other end sits there complete and most of yolk is left behind doesn’t get chopped up

59
Q

What are the types of Meroblastic cleavage?

A
  1. Bilateral
  2. Discoidal (most fishes all reptiles momotremes)
  3. Superficial(insects)
    All of the animals listed all lay eggs so they have huge amounts of yolk because they need to feed on yolk for large amounts of time
    birds
60
Q

describe cleavage in amphibians

A

radial cleavage (they are all dividing outward)
Moderate amount of yolk, largely concentrated at vegetal pole
Animal side has much smaller cells than vegetative(have a lot of yolk in them)
Lot of yolk concentrated at on end of the embryo compared to another
Animal end of the embryo will remain really small than the yolk end until it outgrows the yolk
All of the cells have predetermined fate (if you took out a cell the rest wouldn’t survive cause they cant reassign jobs)

61
Q

describe cleavage in echinoderms

A

radial cleavage
Small amounts of yolk, evenly distributed among cells
Have a animal and vegetal side
These do not determine where the sperm will enter
It will enter somewhere on the animal side
Simple- keep dividing out radially

62
Q

describe cleavage in mammals

A

(except monotremes)
rotational cleavage
At beginning looks similar to others
Small amounts of yolk, evenly distributed among cells
Called rotational because axis of division rotates
Benefit; Undifferentiated, allows for flexibility ( If you rip a cell out the embryo would be fine because another cell would just take the place, nothing is predetermined)

63
Q

Compare cleavage in mammals of that to amphibians

A

Benefit of rotational cleavaget; Undifferentiated, allows for flexibility ( If you rip a cell out the embryo would be fine because another cell would just take the place, nothing is predetermined)

All of the cells have predetermined fate (if you took out a cell the rest wouldn’t survive cause they cant reassign jobs)

64
Q

Describe cleavage in monotremes

A

discoidal cleavage
In monotremes, reptiles, and most fishes
Large amount of yolk at vegetal pole
Benefit to this is that there are no clear boundaries top/bottom
Allows for flexibility during development
1st division cant cut through huge yolk
Cell division occur adjacent to yolk
Tiny little thing at beginning compared to yolk then gets bigger yolk gets smaller

65
Q

describe cleavage in insects

A

superficial cleavage

huge amount of yolk)
Nuclei divide rapidly long before the rest of the cell
No cell division or cytokinesis just mitotic division
Once there’s several 100 nuclei they go to the outer edge of embryo and start forming cell membranes and making new cells and middle remains as yolk
Yolk forms in middle, after cells begin to divide
Polynucleated
Cleavage is rapid cell division with no actual cell growth taking the big egg and dividing it into smaller cells so that they have enough rna and cytoplasm so they can do stuff

66
Q

describe gatsrulation in chicks

A
  • the starting point for gastrulation in chicks is an embryo consisting of a layer of cells, the BLASTODERM, divided into upper & lower layers-the EPIBLAST & HYPOBLAST-lying atop a yolk mass
  • all the cells that will form the embryo come from the epiblast
  • during gastrulation, some epiblast cells move toward the midline of the blastoderm, detach, & move inward toward the yolk
  • the pileup of cells moving inward at the blastoderm’s midline produces a thickening called the PRIMITIVE STEAK
  • although the hypoblast contributes no cells to the embryo, it is required for normal development & seems to help direct the formation of the primitive steak before the onset of gastrulation
  • the hypoblast cells later segregate from the endoderm & eventually form part of the sac that surrounds the yolk & also part of the stalk that connects the yolk mass to the embryo
67
Q

primitive steak

A

a thickening along the future anterior-posterior axis on the surface of an early avian or mammalian embryo, caused by a pilling up of cells as they congregate at the midline before moving into the embryo

68
Q

What is the difference between the male & female gametes in terms of size & motility?

A

in the female gamete, the egg, is a large nonmotile cell

in the male gamete, the sperm, is generally a much smaller motile cell

69
Q

What is the difference between gastrulation and organogenesis?

A

Whereas gastrulation involves mass movements of cells, organogenesis involves more localized changes

70
Q

explain neurulation

A

After gastrulation
Very beginning of organ systems occur here
Neurulation begins as cells from the dorsal mesoderm form the notochord, a rod that extends along the dorsal side of the chordate embryo, as seen for the frog in Figure 47.14a. Signalling molecules secreted by these mesodermal cells and other tissues cause the ectoderm above the notochord to become the neural plate. Formation of the neural plate is thus an example of induction, a process in which a group of cells or tissues influences the development of another group through close-range interactions
Another invagination event
Some part of ectoderm is designated as neural plate, invaginates and folds inward and the fold pinches off forming neural tube which develops into neural tube which becomes spinal cord and brain
Neural crest breaks free from ectoderm and neural tube and migrate through the body forming the peripheral nervous system (sensory system, nerves teeth bones)
Notochord releases chemicals that tell the ectoderm what to do (once its done it disappears
Formed from mesoderm

Neural tube “zips” closed from the middle toward both ends (toward head and end of tail bone)
Very important because if it doesn’t close nervous system doesn’t develop at all or barely
Failure to close at rostral (head) end is lethal
Failure to close at caudal (tail) end leads to spina bifida
Open pockets part way up from bottom
Don’t have any function in legs

71
Q

Mechanisms of Morphogenesis

A

Differential cell division
Different rates of cell division
Asymmetric cell division, divide more rapidly in part then another
During neurulation neural plate cell division occurs more rapidly then elsewhere

Changes in cytoskeletal organization
Microtubules
Actin filaments
Skeleton of cell, help change shape of a cell

Cell migration
Following chemical signals(from notochord)
Using cytoskeletal changes

Apoptosis (programmed cell death)
Some cells are designated to serve some kind of purpose like giving a signal and then its done the cell dies

BIOLOGY 1030 (17 decks)

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