Exam 3 Gen Bio

Question 1

Asexual Reproduction

Answer 1

• offspring are genetically identical
• energy efficient
• more sessile species do this
• less genetic diversity

Question 2

Budding

Answer 2

asex

new individuals form as an outgrowth or buds from bodies of other animals

Question 3

Regeneration

Answer 3

asex

replacement of damaged tissue or limbs but can also regenerate complete individuals

Question 4

Parthenogenesis

Answer 4

development of offspring from unfertilized eggs

Question 5

echinoderms example

Answer 5

as long as a part of the central disc is found in detached portion
it can develop into whole adult animal
(regen)

Question 6

bees

Answer 6

males develop from unfertilized eggs (haploid) females develop from
   fertilized eggs (diploid)

(partho)

Question 7

Whiptail lizards

Answer 7

no males in the species, some females may act as males depending on cyclical hormonal states
Acting as a male during peaks of hormones stimulates release of eggs from ovary in other female
Tardigrades also do this

Question 8

Sexual Reproduction

Answer 8

Large energy requirements

• Energy is spent mating and caring for offspring instead of feeding
• more diversity

Question 9

sexual reproduction requires

Answer 9

the joining of two haploid cells to form a diploid individual:

Question 10

haploid cells

Answer 10

• Genetic diversity come from crossing over in homologous chromosomes and
  independent assortment of chromosomes

Question 11

how are haploid cells made

Answer 11

Gametogenesis – making of gametes

Mating – bringing gametes together

Fertilization – fusing of the gametes

Question 12

Gametogenesis

Answer 12

• production of gametes
• occurs in gonads
• made from germ cells which develop from early cell divisions
• germ cells migrate to developing gonads where they produce spermatogonia or oogonia

Question 13

primary spermatocytes and primary oocytes

Answer 13

Spermatogonia and oogonia (diploid) – multiply by mitosis resulting in

Question 14

after primary mitosis, comes

Answer 14

meiosis, result in haploid cells that mature into sperm and ova

Question 15

Spermatogenesis

Answer 15

• primary spermatocytes undergo first meiosis to form secondary spermatocyte
• second meiotic division will produce spermatids (4) that remain connected by cytoplasmic bridges
• after further differentiation, they become more like what we know

Question 16

Oogenesis

Answer 16

• Oocytes immediately enter prophase of first meiotic division
• Developmental arrest happens often at this point and may last for days, months years (until puberty)
• When meiosis resumes, nucleus completes the first meiotic division
• Daughter cells are unequal in size – secondary oocyte and first polar body
• Second meiotic division of secondary oocyte also asymmetrical – one forms haploid ootid, other forms another polar body
• Polar bodies degenerate, only one mature egg remains

Question 17

Fertilization

Answer 17

the union of sperm and egg

Fertilization results in a single diploid cell - zygote- will then develop into embryo

Question 18

Complex series of events:

Answer 18

1. Sperm and egg recognize each other
2. Sperm is activated, letting it gain access to the plasma membrane of egg
3. Plasma membranes of sperm and egg fuse
4. Egg will then block entry of any other sperm
5. Egg will be metabolically activated and stimulated to start development
6. Egg and sperm nuclei fuse to create the diploid nucleus of the zygote

Question 19

cumulus

Answer 19

Mammalian egg surrounded by thick layer

it is a loose assembly of maternal cells in a gelatinous matrix

Question 20

Zona pellucida or vitelline envelope

Answer 20

Beneath cumulus is a glycoprotein envelope

• Sperm that are activated after entering female reproductive tract are able to penetrate the cumulus and interact with the Zona pellucida

Question 21

When sperm contacts zona pellucida

Answer 21

a species specific glyco-protein will bind to molecules on the head of the sperm

Binding triggers an acrosomal reaction in sperm – enzymatic reaction that can digest a path through the zona pellucida

Question 22

polyspermy

Answer 22

fertilization by more than one sperm BAD

Question 23

Blocks to Polyspermy and Egg activation:

Answer 23

1. First response to sperm entry is blockage of entry of any other sperm
2. Sperm binding causes release of calcium from endoplasmic reciulum of egg
3. Just under the plasma membrane are cortical granules (vesicles) – contain
   enzymes and proteins that will dissolve bonds between zona pellucida and plasma membrane
4. Release of Calcium ions causes release of cortical granules – enzymes will remove sperm binding receptors
5. Rise in cytosolic calcium will also activate egg metabolism and signals completion of meiosis – setting the stage for the first cell division