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biology topic 2 (cells and viruses) > fertilisation > Flashcards

fertilisation Flashcards

(68 cards)

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1
Q

gameotogenesis

A

gametes that make sexual reproduction possible formed in this process

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2
Q

special cells of ova

A

primordial germ cells in gonads

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3
Q

role of mitosis in gameotogenesis

A

provides precursor cells

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4
Q

spermatogenesis

A

formation of spermatoza

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5
Q

precursor cells of sperm

A

primoridal germ cell

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6
Q

1 stage of spermatogenesis

A

-diploid primordial germ cell divides by mitosis to form diploid spermatogonia

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7
Q

second stage of spermatogenesis

A

spermatogenia grows without further division until big enough to be called primary spermatocytes

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8
Q

third stage of spermatogenesis

A

spermatocytes undergo meiosis
first meiotic division results in two haploid cells called secondary spermatocytes

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9
Q

fourth stage of spermatogenesis

A

second meiotic division results in four haploid cells called spermatids

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10
Q

fifth stage of spermatogenesis

A

spermatids differentiate in tubule of testes to form spermatozoa
active gametes capable of fertilising an ovum

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11
Q

oogenesis

A

formation of ova

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12
Q

difference of roles of germ cell of ova and sperm

A

germ cell in testes forms lots of sperm
germ cell in ovaries forms only one egg per cell

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13
Q

first step of oogenesis

A

diploid germ cell divides by mitosis to make diploid oogenia
most oogenia dont develop further
degenerate

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14
Q

second step of oogenesis

A

only one diploid oogenia grows lots of material go into making egg
this cell known as primary oocyte

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15
Q

third stage of oogenesis

A

primary oocyte undergoes meiosis
results in 2 cells
larger cell secondary oocyte
smaller sticks to oocyte called first polar body

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16
Q

fourth stage of oogenesis

A

oocyte dont further divide until after ovulation
ova in ovaries secondary oocyte

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17
Q

fifth stage of oogenesis

A

second meiotic division after fertilisation occurs
-secondary oocyte divides to form haploid ovum
another polar body formed
first polar body divides to make 2 more
degenerate and die as ovum develops

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18
Q

function of polar bodies in ova

A

recieve chromosomes in meiotic division

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19
Q

tasks of sperm

A

-remain in suspension in semen to transport in female duct
-penetrate protective ova barrier
deliver male haploid genome safely
millions made in mans lifetime because their trash

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20
Q

acrosome of sperm

A

membrane bound storage site for enzymes that digest layers surrounding ovum and allow sperms head to go through

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21
Q

nucleus of sperm

A

has highly condensed halpoid chromosomes
condensed state of genetic material reduced amount of energy needed to transport it

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22
Q

mitochondria in sperm

A

tightly packed in middle section provide atp for lashing of tail

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23
Q

microtubules

A

produce whip like movements of tail that keep mature sperm in suspension and help swim towards ovym

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24
Q

tail of sperm

A

flagellum that propels sperm by movement in liquid enviorment

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25
zona pelludica of ova
clear jelly like layer
26
features of ova
-zona pelludica haploid polar body -cell surface membrane of oocyte -cytoplasm with food reserves
27
sporophyte generation
first phase of plant is diploid and produces spores by meiosis
28
gametoohyte generation
second stage of plant is haploid and gives rise to gametes in plants by meiosis
29
sporophyte
main body of plant and is diploid
30
what happens to haploid gametophytes
reduced to parts of anther and ovary -produced by meiosis from spore mother cells
31
where does meiosis occur in flowering plants
anthers resulting in lots of pollen grains that carry male gametes
32
what does each anther have
four pollen sacs where pollen grains develop are diploid
33
whats in each pollen sac
large number of microspores which are gametophyte generation
34
features of gametes
have 2 haploid nuclei
35
names of two haploid nuclei in gametes
tube nucleus and generative nucleus
36
function of tube nucleus
produces pollen tube that penetrates through stigma style and ovary into ovule
37
function of generative nucleus
then fuses with nucleus of ovule to form new individual
38
function of tube nucleus
-produced by tube nucleus -penetrates through stigma and ovary into ovule -generative nucleus then fuses with nucleus of ovule to form new individual
39
formation of egg cells in plants
-meiosis results in number of ova in ovules inside ovary -ovula attached to wall of ovary by pad of placenta -nucellus forms -diploid megaspore- four haploid megaspores by meiosis -3 die and one grows -megaspore has 3 miotic divisions -results in embryo sac that has egg cell two polar nuclei synergids antipodal cells
40
nucellus
complexe structure of coverings that form around tissue of placenta
41
pollination
transfer of pollen from anther to stigma often from one flower to another
42
how pollen is transfered
insects mammals bird wind
43
external fertilisation
female and male gametes released outside parental bodies and meet and fuse in outside enviorment
44
internal fertilisation
of female gamete by male gamete which takes place in body of mother
45
disadvantages of internal fertilisation
not sure if gametes will meet good for complex and simple water animals
46
dis and ad of internal fertilisation
gametes in body makes sure ova and sperm in moist enviorment maximises chance of fertilisation -might not fertilise
47
how sperm move to ova
as sperm move through tract acrosome matures so releases enzymes and penetrates ovum
48
features of ovum in tract
not fully completed meiosis -secondary oocyte with polar body
49
zona pelludica
-ovum released surrounded by protective jelly like layer and some folicles of hair
50
what happens when head of sperm touches ovum
-acrosome reaction triggered -enzymes digest follicle hairs and zona pelludica -one not enough so lots of sperm in ejaculation provide enough enzymes to break down barrier
51
what happens when one sperm manages to touch barrier of ovum
oocyte completes second meiotic devision -haploid egg nucleus fuse with haploid male nucleus
52
why is it important not loads of sperm touch egg
-egg fertilised by to many sperm (polyspermy) and would produce nucleus with to many sets of chromosomes
53
how are lots of sperm prevented form coming to egg
-ion channels in cell membrane of ovum open and close inside of cell -becomes positive instead of negative outside -
54
fertilisation membrane
tough layer that forms around fertilised ovum to prevent entry of other sperm
55
what happens when head of sperm enters ova but not tail
-it absorbs and swells -releases chromosomes -to fuse with those of ovum and form diploid zygote -conception has occurred
56
what happens when pollen land on surface of stigma during pollination
-molecules interact -if recognise each other, pollen grain germinates -
57
where does pollen tube begin to grow
-out from tube cell of pollen grain through stigma into style
58
tip of pollen down tube
-uses hydrolytic enzymes to digest throuugh tube -digested tissues acts as nutrients source and pollen tube grows
59
double fertilisation
in plants where male nucleus fuses with nuclei of two polar nuclei to form endosperm nucleus and other fuses with egg cell to form diploid zygote
60
totipotent
-zygote totipotent -potential to form all types of cells for new person
61
first stage of developing embryo
cleavage -special mitosis which cell divide without normal interphase -happens as embryo travels down oviduct result small identical ball of cells
62
blastocyst
small ball of unspecialised cells as a result of cleavage process
63
embryonic stem cells
tiny cells of early human embryo
64
role of outer layer cells in blastocyst
form placenta and inner cells already lost some ability to specialise
65
pluripotent
can all types of cells for future but not tissue like placenta
66
pluripotent embryonic stem cells
cells that can change into any cell but not tissue like placenta
67
cell determination
cells already predestined and determined to become one type of tissue -even if surgically removed and paced on other part of body will still produce what predertimined to
68

biology topic 2 (cells and viruses) (10 decks)

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