Topic 6: Animal Reproduction and Development Flashcards
Asexual reproduction
Generation of new individuals without the fusion of the egg and sperm.
Sexual reproduction
Generation of new individuals through the fusion of haploid gametes.
what are Eggs (ova) and sperm compare their size and motility.
eggs: female gamete, large and nonmotile. sperm: male gamete, smaller and motile.
zygote
a diploid cell from the fusion of egg and sperm
is the majority of the human lifecycle diploid or haploid?
Diploid , only gametes are haploid.
What are the 3 modes of asexual reproduction, describe them and examples of animals that do each
Fission: animal breaks into 2 equally sized individuals. ex: sea anemone Budding: large parent produces outgrowths which breaks off from the main body. ex: stony corals. Fragmentation: individual disintegrates into many small pieces which grow back into a full-sized, functional individuals. ex: annelid worms, sponges, cnidarians tunicates, flatworms.
Difference between offspring in sexual and asexual reproduction
In asexual repro. offspring are genetic clones, sexual repro. genetic variation.
what’s parthenogenesis
A form of asexual reproduction that uses the reproductive tract of the female, and an egg produces offspring without fertilization (so no sperm).
Parthenogenesis progeny can be haploid or diploid true or false, explain
true if not fertilized the offspring are haploid, if fertilized the offspring are diploid.
Hermaphorditism
Individuals have both male and female reproductive systems. So any two individuals can mate with eachother.
in humans we call it intersex
what’s a drawback to sexual reproduction
energetically expensive
whats Monoecious, examples of animals that are?
both gametes/gonads within same body ex: barnacles, clams, tapeworms
mono=one like one body
whats Dioecious
only one type of reproductive system in the body
What’s protandry and protogyny in hermaphordites
Protandry: means they develop male organs first, protogyny means they develop female organs first
think gyny like gynocologist (so female)
what adaptations have allowed animals to overcome the limitation of finding a mate being energetically expensive
Hermaphorditism, and Harems
what are Harems?
Groups of 1 male to many females.
common in aquatic animals
Explain sex reversal in the bluehead wrasse fish harems. Why does it happen
When the 1 male dies, a female (usually the largest and oldest) will get male gonads to ensure enough males in the population to protect and defend the harem.
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Most sexual animals have reproductive cycles that correspond to__
various changes in the environment. ex: mating seasons ensurs that there will be enough food when offspring is born.
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Sexual animals reproductive cycles are usually controlled by _ which are regulated by __
hormones, environmental cues.
what can disrupt and reduce reproductive cycles? (especially in nothern/artic species). example?
Climate change. Ex: Caribou migrate to calving grounds in the spring, which have high food availibility due to all the plants. But increasing temperatures mean plants arrive earlier so when calves are born, the plants are too far developed and hard for them to digest.
what are the advantages of asexual reproduction
Allows for favourable genotypes to remain in the population for a long time. Energetically less expensive. Maintains high population size.
Advantages of Sexual reproduction
Increases genetic variation which may allow offspring to survive in less ideal environments. Genetic recombination allows for adaptation. Allows the population to reduce deleterious mutations.
Fertilization
brings eggs and sperm together to form zygote
what is Internal fertilization? what does it require? what’s an advantage of it
sperm is deposited in or near the female reproductive tract. Requires coordinated mating behaviours and systems. Advantages: keeps gametes safe and viable.
what is External fertilization? what does it require and why?
females release eggs into the environment to be fertilized by sperm that is also released. Requires moist habitats to prevent dehydration and so sperm can swim.
describe spawning (type of external fertilization)
individuals are clustered together and release gametes at the same time.
what can stimulate the release of gametes in external fertilization? examples?
Chemical/behavioural cues. Ex: female frogs will release eggs only when male clasps her during mating behaviours. pheromones can also affect individual behaviour to stimulate mating (like in moths).
Ensure that the opposite gamete is nearby for fertilization to occur.
Which produces fewer gametes internal or external fertilization
internal (less space)
How are offspring of egg-laying animals protected as they develop
Eggs have hard calcified shells and internal membranes
how are marsupials offspring protected as they develop
embryos reside in the pouch, spending only a short time in the uterus of the female.
when are gametes established in embryonic development
early, but remain inactive until individual is sexually mature.
How do animals that lack gonads produce gametes? Ex of animal
Gametes are produced directly from undifferentiated cells lining the coelom, where they mature and are released into the coelom. Ex: polychaete worms in annelida.
How do animals with accessory tubes and glands as their reproductive system produce gametes? Ex of animal?
Males have testes that produce and store sperm until ejaculation. Females receive sperm in the spermathecae (sacs), which can store sperm for days to years until the female releases the sperm to fertilize the eggs. Ex: insects.
Reproductive tracts in vertebrates are highly varied describe females variations. (Mammals vs non mammals and marsupials)
Most have 2 ovaries. Humans have 1 uterus but many mammals have 2. Number of openings can vary among animals. Many non mammalian vertebrates have a cloaca (one opening for digestive, excretory and reproduction). Marsupials have 3 openings (one for each uterus and 1 birth canal).
Reproductive tracts in vertebrates are highly varied describe males variations. (In fish, reptiles)
Mainly differ in copulatory organs. Fish just release sperm into the environment but some have modified pelvic fins to form a channel for sperm transfer. Most reptiles release sperm from the cloaca. Some have penis like structures that are inserted into the female reproductive tract.
Animals usually mate with more than 1 partner what is this called
Polygamy
What’s monogamy examples of animals that do this
Relatively rare among animals, including most mammals. Ex: Canada geese and wolves “mate for life”. Males and females have adaptations that reduce the chance of other partners succeeding with the mating following (like chemical pheromones)
The male reproductive system includes two main anatomies describe them:
External: scrotum and penis
Internal: gonads, accessory glands, and ducts
What are the male gonads
The testes
Where in the testes are sperm produced (spermatogenesis)
In highly coiled seminiferous tubules.
What 2 parts are contained in the testicle
The testis and the scrotum
Why is the testis external
To maintain its temperature 2 degrees cooler than core body temp, sperm can’t be too hot
What are the 3 sets of accessory glands in the male reproductive system
Seminal vesicles, prostate gland and bulbourethral glands
Describe what the seminal vesicles produce
produces 60% of the semen volume; yellowish, thick and alkaline.
Describe what the prostate produces
Thin, milky fluid containing anticoagulant enzymes and citrate secreted directly into the urethra.
Describe what the bulbourethral glands produce
Fluid to neutralize any acid urine prior to ejaculation, below the prostate.
What’s Spermatogenesis. When does it occur?
The formation and development of sperm, continuous and occurs throughout adolescence and adulthood.
How many sperm cells are produced daily, how many weeks does it take per sperm cell to complete
100s of millions produced daily, takes 7 weeks per sperm cell to complete.
Each of the four daughter cells produced by meiosis produce a
Viable sperm
Acrosome
Contains enzymes to help sperm penetrate the egg
What is the starting cell called in spermatogenesis
Spermatogonial stem cell
in spermatogenesis
Whats the cell called after two mitotic divisions, at the start of meiosis 1.
Primary spermatocyte
What’s the first haploid cell called in spermatogenesis
Secondary spermatocyte (after meiosis 1)
What is the head of the sperm called, what is on the tip of the head
The haploid nucleus, on the tip is the acrosome
What does the mid piece of the sperm contain
The mitochondria
What is the tail of the sperm for
Movement
What are the two main anatomies of the female reproductive system
External: clitoris, and two sets of labia
Internal: gonads, ducts, and chambers
Describe the Ovaries
Female gonads, flank the uterus and held in place by ligaments. Outer layer is packed with follicles, each containing a oocyte (egg)
Oviducts (fallopian tubes)
Connect the ovaries to the uterus diameter as thin as human hair. During ovulation the egg is released in the oviduct and is transported through cilia lining the tube.
Uterus, cervix?
Thick muscular organ, inner lining is endometrium, supplied with tons of blood vessels the neck of the uterus is the cervix, which opens to the vagina.
Oogenesis
The formation and development of eggs (ova), prolonged and interrupted in females. Immature oocytes form in the uterus before birth of the fetus but do not complete development until sexual maturity is reached.
How many of the daughter cells produced in meiosis become a mature gamete
Only 1 out of 4 due to unequal cytokinesis.
What is the starting cell of oogenesis called
Oogoniun
What is the first haploid cell in oogenesis
The secondary oocyte
