Animal R+D+G Flashcards
define sex
the fusion of genetic material from two different parents
pros of asexual reproduction
higher rate of offspring per organism
no energetic costs
cons of asexual reproduction
transmits mutations and no genetic variation
4 methods of asexual reproduction
fragmentation - break body bits and regrow lost parts
binary fission - divide into two creating daughter cells
budding - offspirng grows from parental body cells
parthenogenesis - virgin birth,
in stressful conditions _______ is favoured over ______ reproduction because in stress ________ is needed
sexual reproduction
asexual reproduction
genetic diversity
how old is sexual reproduction
1.5 -2 billion
3 stages to sexual reproduction
gametogenesis
mating
fertilisation
both ______ and _____ are highly conserved but ______- has huge variety
gametogenesis
fertilisation
mating
describe external mating
stuck in the same spot e.g. giant clam - cast sperm into environment, more mobile species will put sperm as close as possible to the female
_______ is essential for external ferilisation
water
what are the limits to external fertilisation?
cant control the delivery
huge number of gametes required
high energetic cost
internal fertilisation can be _______ or _______
indirect or direct
describe the mating strategy of the Sminthurus virdis
a neat spermatophore made from males testes - stalk with spermatophore on top
no courtship ritual
desccribe the mating strategy of the Allacma gallica
male deposits several spermatophores
- pushes female towards them - increasing likelyhood that a female accepts the spermatohore
- males eat the spermatophore of others males to increase paternity
direct transfer of sperm requires an __________ organ
intromittent
describe sexual dimorphism in the blanket octopus
females are up to 2 meters
males are 1mm
males fill sperm n an arm like organ mating arm spits offf and swims towards the` female
define hermaphrodite
male and female reproductive organs
cant self fertilsie
describe the costly mating of the bean weevil (callobrichus)
males penis has spines - lacerate the reproductive tract
- shortens life span
- increases time between female copulations
describe the costly mating in bed bugs
females dont have genital openings
males pierce body and place sperm in the haemocoel
sperm move ton eggs
describe sexual canabalism
and why it is adaptive
female eats male
- nutritional benefit to female
- maximises paternity by prolonging copulation
- minimise paternity monopolisation
three key processes in gametogenesis
meiosis
- spermatogenesis in males
- oogenesis in females
briefly describe meiosis
homologus chromosomes
genetic recombination occurs
two rounds of cell diviision
in meiosis 2 the cell splits and produces 4 gametes
in humans sperm is produced in the _________ of the testes, and then is moved to the _______ where they are stored, the ______ transfer sperm to the penis
seminiferous tubules
epidiymis
vas deferens
seminal fluid makes up ____ of semen
90%
in fruit fly sperm is formed in the ____ of the testes and picks up seminal fluid from the _____
hub
accsessory glands
spermatogonial stem cells divide by ________ to produce _______ spermatocytes. Then each spermatocyte divides by ______ to form two secondary spermatocytes. Meiosis 2 occurs in which each secondary spermatocyte divides into _________ _______ _______
mitosis
primary
meiosis
four halploid spermatids
differences between spermatogenesis in inverts and humans
inverts, cysts within testes
humans - seminferous tubules
inverts - distal to proximal
humans - periphery to lumen
inverts in larval stage
humans - puberty
inverts - few days but 10,0000 per day
mammals - 74 days but 3000 million per day
inverts store in seminal vesicle
humans store in epidiymus
use the: - house mouse - zebra fish - nematodes as examples of diverse sper,m
house mouse has hooked sperm enables them to move in groups
zebrafish have more mitochondria
nematodes have pseudopodia instead of a tail allowing a crawling movement
descrine the sperm heteromorphism adaptation in butterflies
long fertile and short infertile
adaptation for sperm competition
infertile may act as a plug to prevent other males
describe oogenesis
primary oocyte divides germinal vesicle breaks down (nucleus)
meiosis 1
metaphase plate moves towards the edge by telophase one of the daughter cells contains very ittle cytoplasm
small cell = firstr polar body
large cell = secondary oocyte
second meiotic division:
polar body divides as well as secondary oocyte makes three polar bodies and one ovum
the ovum has more of the cytoplasm etc
compare oogenesis in inverts and humans
inverts: egg develop from distal region to proximal
human: oogenesis within a folicle grows for 2 weeks ruptures to release an egg
inverts: starts in larval stage
humans: 400,000 folicles folicles at birth no ovulation until puberty
inverts: 100 eggs per takes a few to mature an egg
humans : 1 egg matures each month
inverts released into uterus for fertilisation
human: folicle ruptures oocyte enters fallopian tube
inverts: egg develops outside the insect
humans: embeded into uterian wall
what hormone is released by females during puberty to start their period ? what does it do?
gondaotrophin releasing hormone
stimulates FSH (folicle stimulating hormone) and LH (lutenising hormone)
what happens to males at the start of puberty?
FSH causes the development of leydig cells which secrete testosterone stimulating spermatogenesis
- develops seminferous tubules and spermatogensis
what do FSH and LH do in females
FSH - stimulates folicle development and secretion of estrogens
LH - stimulates maturation of follicles and release of ova at ovulation
role of oestrogen in females
enhances folicle growth and grows endomethium
role of progestrone
grow and maintains endometrieum for pregnanct secretes nutrients to embryo
where is gondotrophin releasing hormone released from
hyperthalamus
when do LH and FSH peak?
ovulation
go through the series of events from release of Gondotrophin to mensruation
GnRH released from anterioir pituritory gland
LH released later
stimulates folicle growth
oestrogen released
LH surge
folicle realses egg
corpus luteium (egg housing) degenerates
protesteone and estorgone released
endometerium expands
if egg is unferilised then menstruation will happen
how does the birth control pill work, how effecrtive is it?
synthetic oestrogen and progesterone
no oestrogen peak
changes cervical mucus - more harsh for sperm
five stages of development
fertilisation - zygote formed
cleavage - cell division forms blastula
gastrulation - formation of tissue layers and axis
organogenesis - fromation of organs
morphogenesis - body shape formation
the mitochondria of the zygote all comes from the ______
mother
zygote has two spheres the _______ which contains the ______and the _______ which contains the ______
animal - nucleus
vegital - nutrients
describe the process that occurs after fertilisation in amphibians
vegital clear - animal is opauque
cortex rotates so site of ferilisation is at a junction between the animal and vegital spheres
in amphibians where does the crey crescent sit?
opposite the site of fertilisation
what is cleavage? what does it form?
a rapid series of cell divisions following fertilisation
- typically double
- each cell = blastomere
- ball of cells = morula
- blastula = hollow ball of cells
there is very little _____ during cleavage
growth
3 patterns of cleavage what determines the pattern?
complete
incomplete - discoidal
incomplete superficial
determined by the amount of yolk and spindle orientationo
when does complete cleavage occur
no or small amount of yolk
- where no yolk even division occurs
when does incomplete discoidal cleavage occur
lots of yolk - cleavage furrows dont penetrate the yolk - blastodisc froms on top of the yolk gives rise to embryo
when does incomeplte superficial cleavage occur?
when the yolk sits in the middle of the egg
cytokenesis doesnt follow nucleus division. nuclei migrate to the edges
plasma membranes grows inwards partioning the nuclei
when mitotic spindles form at right angles or parallel the cleavage is ?
radial
describe the mitotic spindles in rotaional cleavage
first division is parallel to a-v axis second is at right angles
in early development cells are _________ . At ________ their fate becomes _______. At _________ th cells become structurally and functionally specialised
totipotent
determination
differentiation
what is gastrulation?
where the blastula becomes an embryo
- tissue layers begin to fall
what are the three tissue layers formed by gasturlation?
endoderm - inner layer produces digestive tract
ectoderm - epidermis and nervous system
mesoderm - bone muscle liver, heart and blood vessels
describe the process of gasturlation in mammals
blastula invaginates at vegital hemisphere
cells migrate towards the blastocoel and become primary mesenchyme cells
invagination continues - archentron which becomes the gut
secondary mesemchyme cells attach to vegital pole
in protosomes the mouth forms from the blastopore where as deuterosomes the anus forms from the blastopore
breief description of early development in birds
cleavage forms a blastodisc
epiblast forms the embryo and hypoblast forms extraembryonic membranes - the blastocoel lies in betweeen the two
gastrulation occurs when hensens node moves across the
neurulation
formation of the nervous system, ectoderm thickens above the notochord
edges of thick area continue to thicken to give ridges
neural crest cells produce what during neurulation?
peripheral nerves
somites produce what during neurulation?
vertebrae ribs, muscles and trunk
define the following parts of the egg. - yolk sac - amnioitic sac - chorion allantois
yolk sac = nutrient transfer via blood vessels
amniotic sac = protection surronding embryo
chorion = gas and water exchange, surronds embryo and yolk sac
allantois = waste storafe in mammals incorporated into ambilical chord
what proportion of sperm survive the virgina
1 in 1 million
mammalian egg structure
germinal vesicle = contains nucleus
ooplasm = cytoplasm of egg
viteline layer - cell membrane surronding ooplasm
zona pellucida - extracellular matrix that contains glycoproteins
surronded by corona radiata - layer of folicle cells
structure of sperm
head - nucleus
neck - centriole
midpiece - mitochondria which provides energy for movement
tail - drives the sperm forward
describe how the sperm penetrates the egg in mammals
vigorous motility to get through corona layer
undergoes acrosome reaction to get through the zona pelcuida
sperm and oocyte plasma membranes fuse - protein recognition and attahcment
sperm nucleus enters ovum
membrane and zp proteins block polyspermy
describe how the sperm penetrates and fertilises the egg in sea urhcins
protective jelly coat dissolved by enzymes from sperm
sperm binds to receptors on microvilli which recognise species specific bindin proteins
potrusion from sperm head and membrane fusion occurs
how do sea urchins protect themselves from polyspermy?
by changing their electrochemical gradient
ZP2 egg protrein is in the top __% of most divergent molecules
5
one of the fastest evolving metazoan proteins is ?
lysin - dissolves egg envelope in abalone molluscs
three controlers of development
cytoplasm
genes
external environment
what is genomic activation?
the transiion from maternal control to embryo control
why is early development under maternal control?
in early embryos there is no transcription
all proteins and enzymes come from the cytoplasm
differnetiation is caused by _______. How was this proved
differntial gene expressionn
take adult skin cells and mature them in a medium of transcription factors
nucleus of somatic cell transferred into enuclated egg and a normal embryo was produced.
also shows genomic equivalance and that the cytoplasm controls earlt devlelopment
what is genomic equivialnce ?
no infomation is lost in the early stages of embryoninc development
where are the cytoplasmic factors held? how do we know?
gray crescent
- split the grey cresecent if split in two there are two normal tadpoles
- if split unevenly with all grey crescent on one side then one tadpole and one belly piece
desccribe cytoplasmic segregation. and why different segregation results in different outcomes
factor unequally distributed in the cytoplasm and ends up in some daughter cells but not others
most of the nurients are at the vegital poles
- result depends on where the segregation occurs
- horizontal - remain embryonic, only one has nutrients
- vertical - normal but small since both have nutrients
what is developmental induction?
where the presence of one tissue effects the development of another
give an example of primary induction in birds and amphibians
amphibians - spemann organiser - dorsal lip of blastopore, which induces overlying ecotderm to form neural tissue
hensens node in birds
induced from the central nervous system
give an example of secondary induction
forebrain starts to bulge and optical vesicle forms causes lens placode tissue to form
differentiates into a lens indues surface layer to become a cornea and the layers behind it to be an optic cup
what morphogen controls the anterior prosterior axis of the limb, how does it do so?
BMP2
smallest dose of BMP2 causes the growth of the little finger etc
male male zygotes wont form a ____ because the inner cell mass is _______ controlled> where as female female zygotes wont produce a ______ becuase this develops from ______ genes
embryo
maternally
placenta
paternal genes
demonstarte how the same gene on maternal and paternal chromomes can cause different phneotype
prader willi syndrome - deletion on paternal chromosome 15
- compulsive eaters with learning difficulties
angelman syndrome
deletion in maaternal chromosome 15
- mobility issues and permanet happiness
give the four types of genes involved in segmentation and what each one does
gap genes - organise large areas along the anterioir prosterioir axis
pair rule genes - divides each embryo into units of two segments
segmentation polarity genes - determine segment boundries
homeotic genes are expressed along the length of the body and determine what the segments will become
homeotic genes are also known as what?
HOX genes
apoptosis
programmed cell death
how many of c elegans 1090 stomatic cells are programmed to die
131
what enzymes stimulates apoptosis in human embryos hands ?
caspase
- removes webbing between fingers
describe the infuence gut bacteria have on mpuse development
induce gene expression in the intestine which is essential for normal capillary development
describe spina bifidia and how it is caused
where the neural tube fails to close at the posterioir end - part of the spine doesnt develop properly
describe anencephaly
where the tube fails to close at the anterioir end - brain dioesnt develop properly gap in
the chances of anencephaly and spina bifidia are redcued by
adequate folic acid when pregnant
what causes cretinism, what are the symptoms
lack of iodine
symptoms include - drawfism and large heads
what is sonic the hedgehog protein involved in?
fomration of the neural system
what is the average rate of egg failure and what about in kakapos
10-15% average
70% for kakapo
what are the two major types of cause of egg failure
fertilisation failure
embryo death
ways an egg may fail because of fertilisation
sperm doesnt reach
sperm or ovum dysnfunction
female antisperm response
what percentage of sperm that enter vagina female die?
0.00001%
what part of the reproductive tract does fertilisation occur in
infundibulum
if you bypass the uterus even ____ sperm gets to the egg.
dead
describe how you can test the most succsessful bird sperm
female secretes glycoporteins into the outer perivitelline layer that trap sperm
- can see the sperm that made it to the egg
- measure them
___ sperm have a competitive advantege over ____ sperm as long as the ______ and the _______ are equal size
long
small
midpiece and tail
in birds polyspermy is normal which means?
sperm selection continues after entering the egg
polyspermy is required for surivial in many bird eggs whuch part of the extra sperms is needed and how do we know this
injected single sperm with many proteins extracted from over 200 other sperm
only the sperm protein is needed
4 mechanisms of cloning
natural
embryo splitting
reprogramming of somatic cells
nuclear transfer
describe embryo splitting as a mechanism of cloning - who did it first
bisect the egg of a salamander
manipulatied monozygotic twins
spemann first to do it with a hair from his baby
reprogramming of stomatic cell is basically ____________. and involves
revevrsing differntiation
- take cells and feed specific growth factors
why is stomatic cell nuclear transfer controversial
invasive
tech porblems
ethical problems
who were the first cloned mammals?
megan and morag the sheep
how where megan and morag cloned
arrested embryo cells in G0 of interphase by depriving them of a growth factor
arrested cells into enuclated eggs and stimulated them
planted into surrogate
why what was the argument against megan and morag being the first clones?
they had come from an embryo cells - argued that they hadnt lost complete totipotency
how was dolly cloned
adult sheep mammary glands arrestred in G0
cells fused with enuclated eggs and transplanted intoo a surrogate
why is cloning better than genetic modification of all lambs in an atempt to create theraputic milk
each trasngenic lamb requires 51.4 ewes
each transgenic clone requires 20.8 ewes
what disease does polly and her sisters milk help to treat
haemophilia - has blood clotting factor nine
first monkey to be cloned
ANDi - rhesus monkey
for how long did cloning bring the pyrenean ibex back from extinction?
7 minutes
why cant cloning ever bring back a loved one
only dna clones not cytoplasm ones
clones have their own mutations
differnent environments
aging - telemoeres shorten with age- clone has telomere of parent
large foetus syndrome - clones grow larger and need to be implanted into larger surrogates
what disease is caused by a lack of dopamine
parkinsons
what is evo devo
evolutionary development
- looks at how changes in the genes that regulate development affect the adult forms of organisms and how these changes have occured over the course of evolution
what gene codes for eye growth in mice
Pax 6
how did darwin know that gosseneck barnacles were crustaceans
by looking at their larval stage
describe th emutatioon in the arhtopods that lead to the insects
arthropods have legs on their abdomen
insects have a mutation which produces a protein that represses the distal less gene in the abdomen which is essntial for leg formation
all insects legs orignate on the thorax and not the abdomen
describe the roles of both BMP4 and gremlin in forming the ducks webbed feet
BMP4 expressed between the developing toes it insructs the cells to undergo apoptosis which destroys the webs
gremlin is a BMP4 inhibitor expressed around the digits to prevent toe dropping off
in ducks gremlin moves between toes allowing webbed feet
describe temporal shifts in expression in bolitoglossa
webs disappear as they mature e.g. rostratus
some e.g. occidentales expression of these genes is slowed down allowing for suction cups enabling arboreal life
what triggers egg production in mosquitos
a blood meal
- stimulates vitellogenin production
describe the wet and dry season form of the squinting bush butterfly
dry is darker with less obvious eye spots itcomes out when it is less than 20
more than 24 and the wet form will develop
polyphenism
two phylogenetic pathways dependant on climate
describe the polyphenism in the moth nemoria arizoniaria
spring larvae feed on oak flowers and look like them
summer form look like oak leaves and eats stems
describe the polyphenism in daphina
encounter chaoborus (predator) and get spiky helmets - helmet induction occurs around the larvae of chaoborus it is a trade off since those with helmets produce fewer eggs
describe the polyphenism in spade foot toads
live in desert ponds
dry up quickly following a rainfall
eat insects and alage meaning slower develoment since poor nutrition
pond could dry up causes tadpoles to have a wider mouth and a stronger jaw
intestines become modified to eat meat
start to eat the other tadpoles
