Unit 06 + 07: Animal Reproduction and Development Flashcards
What are the two types of reproduction.
Sexual and asexual.
Describe sexual reproduction.
“Typical”
Male and female gametes produced via meiosis fuse to form zygote.
Each parent gives 50% of their DNA, and all offspring genetically vary.
Describe asexual reproduction.
“Atypical”
One parent (female) produces all offspring, makes copies of herself, therefore gametes are optional.
Offspring genetically identical.
Do animals reproduce by sexual or asexual reproduction?
Both! Depending on which animal and if the conditions are right.
What conditions allow for an animal to reproduce asexually?
Stable and favourable conditions, allowing to make offspring fast.
What are the 3 forms of asexual reproduction?
Budding, Fission, Parthogenesis
Describe budding as a form of asexual reproduction and an animal in which it occurs. Does it happen in males or females?
An outgrowth that enlarges and separates from the parent.
Hydra.
Both males and females.
Describe fission/fragmentation as a form of asexual reproduction and an animal in which it occurs.
Parent separates into 2 or more similar sized or smaller individuals.
Anemone.
Males or females.
Describe parthenogenesis as a form of asexual reproduction and an animal in which it occurs.
Unfertilized eggs develop into an individual.
Various animals.
Females only.
How do wasps and bees perform parthenogenesis?
Queen produced haploid eggs, some get fertilized, some don’t.
The ones that stay haploid become male workers drones, while the fertilized become female queens.
How do invertebrates perform parthenogenesis?
Lay diploid eggs, copies of parents via mitosis.
How do vertebrates perform parthenogenesis?
Lay diploid eggs, genetically modified via meiosis.
What are dioecious species? Name a difficulty they face.
“Two houses”
Species that have either male or female parts. Difficulty finding mate.
What are simultaneous monecious species? Name a difficulty they face.
“One house”
Male and female parts on one body. Also known as hermaphrodites.
How can simultaneous monoecious species fertilize?
Cross-fertilize - mate with others, making offspring genetically different from parent.
Self-fertilize - mate with self causing offspring to be identical to parent. Easier to find mate if can reproduce with itself.
What are sequential monecious species?
Species that start off as one sex and then change into another later in life.
What are the three types of sex reversals, an animal that performs it and their rarity?
Protandry - male to female (common) : clown fish
Protogyny - female to male (rare) : other fish
Multiple sex changes (rare) : whiptail lizards.
Why are whiptail lizards interesting from a sex change perspective.
All are female, but some act as a male.
Female like - right before ovulating (high estradiol)
Male like - right after ovulating (high progesterone)
Think: Lizards are Lesbian
What is gametogenesis?
Formation of gametes.
What is spermatogenesis?
Formation of small, motile sperm. Many are rapidly and continuously produced.
What is oogenesis?
Formation of large, non-motile eggs. Few are slowly produced.
How many of the 4 cell products of spermatogenesis become sperm?
All four!
When in humans does sperm development start and end and how long does it take.
Starts at puberty and continues for rest of male’s life.
Takes 3-4 weeks.
How many of the 4 cell products of oogenesis become sperm?
1, the rest become polar bodies
When in humans does egg development start and end and how long does it take.
Starts at pre-birth, pauses until puberty, until menopause where it stops.
What is ovulation?
The release of eggs at the midway point of the female cycle.
What structures of the egg ensure that only 1 sperm get in.
Plasma membrane, vitelline layer and jelly coat.
Describe the different types of yolk distributions.
Isolecithal - small amount of even yolk. Found in mammals, very short development, not very energetically costly.
Mesolecithal - Medium amount of yolk, uneven distribution. Medium development period ex. frogs
Telolecithal - Large, even distribution of yolk. Very long development , birds
What is an acrosome?
Head of a sperm filled with digestive enzymes
What is the first step of fertilization?
Sperm touches the eggs jelly coat, triggering acrosomal reaction.
What are sperm binding receptors?
Receptors on egg that that use molecular recognition that sperm is of same species as egg.
What IS the acrosomal reaction?
2nd step of fertilization.
Acrosome makes hole in jelly coat allowing for binding of protein molecules to bind to receptors on egg plasma membrane.
What is the third step of fertilization?
Fusion of sperm and eggs membranes, triggering depolarization (allowing Ca^2 to enter).
Triggers meiosis 2 in second oocyte
Blocks polyspermy
What is polyspermy and why is it bad?
When more than one sperm enters an egg. If it were to happen, would be an abnormal number of chromosomes and zygote would die.
What is external fertilization and what does it require?
When eggs are fertilized outside the female.
Requiring moisture so that
