Reproductive processes and genetics Flashcards
1
Q
why are reproductive processes needed
A
- for perpetuation of the species
- not aimed towards homeostasis
- not for the survival of the individual (but for the species
- animals can reproduce sexually and asexually
2
Q
prokaryokes
A
- reproduce by cloning, one cell divides and gives rise to two identical cells (continuously copy)
3
Q
eukaryotes
A
- reproduce sexually
- recombination of new genetic material
4
Q
what are different types of reproduction
A
- budding/fusion
- parthogenogenesis
- sexual reproduction
5
Q
budding/fusion
A
- an animal produces a copy of itself without embryonic development
- asexual cloning
ex. sea anemone
6
Q
pathenogenesis
A
- an unfertilized egg develops into an embryo
- asexual cloning
- some insects, some reptiles and some sharls
7
Q
sexual reproduction
A
- union of male and female gametes
- two haploids sets of chromosomes combine to form a new diploid set chromosomes
- half the genetic material from each parent
8
Q
why sexual reproduction
A
- sex allows different beneficial mutations arising in different individuals to come together enhancing adaptation to changing environments
- cloning passes on all harmful mutations - sex allows an individual to pick up a healthy gene from a mate for its offspring
- increasing genetic diversity - sex reduces the effectiveness of paracites that have evolved to attack a specific genome e.g snails
9
Q
r selected reproduction
A
- rate of population growth
- reproduction resources are put into producing many offspring (1000s) with no parental care and minimal nourishment
- only a few of the offspring survive, overwhelming numbers ensure success
- large number of offspring, little parental care
10
Q
k selected reproduction
A
- carrying capacity
- relatively few offspring, with most of parental reproductive energy used for nourishing and/or protecting the offspring
- a greater percentage will survive
- small amount of offspring, large parental care
11
Q
intermediate
A
- intermediate numbers with some noureshment and parential care
12
Q
oviparous
A
- young develop in eggs after expulsion from the mothers body
- fertilization occurs outside the body
- snails, fish and amphibians
- maternal contribution is soley from nucleus of egg and yolky cytoplams
- eggs are without a shell ( they have a membrane so sperm can fertilize )
- eggs are released into the environment and hen fertilized outside the genital tract
- development outside the maternal genital tract
13
Q
ovoviviparous
A
- production of eggs that use yolk to develop partly or fully within the body of the mother
- fertilization occurs internally but no additional nutrients provided
- birds, some snakes like vipers
- fertilization of the egg occurs in the genital tract and the shell is then produced
- some very early development can occur in the genital tract before the eggshell membrane is produced
- some opportunity for maternal contributions to affect development in addition to the nucleus and yolky cytoplasm
ex. growth factors secreted by gentical tract
14
Q
viviparous
A
-production of young within the mothers body that use maternal blood nutrients to develop and that emerge live
- mammals
- usually utilize a placenta (without the need for the yolk)
- have internal insemination and fertilization
- development within the maternal genital tract ( marsupials are an outlier - development is completed within pouch)
- comparatively fully developed young, sometimes free living but there are variations
15
Q
altricial
A
- born that absolutely dependent on continued parental care
- rats and songbirds
16
Q
precocial
A
- born well developed (open eyes, developed legs, alert) that can leave their parents and feed independently
- cattle and chickens
17
Q
monotremes
A
- spiny anteater or echidna
- platypus
- an evolutionary transition between ovoviviparity and viviparity
- a porous egg remains in th e female genital tract where the embryo can develop after fertilization
- recieves some nutrients secreted from the tract
- laid with only a small amount of remaining yolk
18
Q
estrus
A
- receptivity to mating
19
Q
continuously polyestrous
A
- cycles occur uniformly throughout the year
- cattle and humans
20
Q
seasonally polyestrous
A
- cycles confined to a specific time of year
- short day breeders ( breed during fall, rely on increasing concentrations of melatonin to trigger reproduction) - sheep, goats and deer
- long day breeders( breed during spring with days getting longer, rely on decreased melatonin to trigger reproduction) - horses
21
Q
seasonally monoestrous
A
- a single cycle followed by a long period of anestrous
- dogs
can only be impregnanted during the period
22
Q
seasonal breeding
A
- seasonal anestrus prevents females from giving birth when survival of the offspring is unlikely
- most seasonal non tropical breeders give birth in spring
- environmental and nutritional conditions support offspring growth
- partly controlled by circannual biological clocks entrained to photoperiod
- ## also influenced by temperature male prescence and food sources
23
Q
what are synchronized mating behaviours
A
- environmental cues = spring
- internal cues - eggs are ripe
- pheromones and other biologically produced agents (to ensure both sexes are ready to reproduce or even a species as a whole)
- elaborate courtship displays likely advertise the genetic fitness of the male
- usually but not always involves the male
- great examples can be found in spiders and birds
24
Q
spontaneous ovulation
A
- do not require coitus to ovulate
- cattle sheep pigs dogs and humans
25
Q
induced ovulation
A
- required coitus to stimulate ovulation
- sensory receptos in vagina and cervix
- mechanical (cat, rabbit) or semen components (camel)
26
Q
ovarian (follicular) cycle
A
-oocyte matures and is ovulated
- estrogen dominates
27
Q
uterine (luteal ) cycle
A
- uterine lining prepares for embryo implantation
- progesterone dominates
