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Meiosis parts of animal development (2)
- Gamete formation
Mitosis parts of animal development (4)
Two processes of Gametogenesis
Spermatogenesis & Oogenesis
Where does Gametogenesis occur?
In gonads of males & females
What does gametogenesis do?
Divides homologous chromosomes into different haploid cells
What are germ cells?
Cells that give rise to gametes
Where are germ cells found?
What is spermatogenesis?
Production & maturation of sperm in testes
How many sperm cells are formed in testes?
4 haploid sperm cells
What happens to the nucleus of the haploid sperm cell?
It condenses into a head.
Function of flagellar tail
What does the sperm head of all sperm cells contain?
What aids the sperm cell in penetrating the egg?
What is oogenesis?
Production & maturation of ovum in the ovary.
What is the result in production of oogenesis?
one haploid ovum and 3 polar bodies
In females, what are germ cells called?
When do primary oocytes develop in females?
Prior to birth
In females, when does meiosis halt and continue again?
Halts after stage one, continues after ovulation
What is fertilization?
Union of male & female gametes to form a zygote
Functions of Fertilization (3)
- # of chromosomes becomes diploid
- Combination of maternal/paternal genes
- Activates egg to begin development
What allows the sperm into the egg?
Gamete recognition proteins
More than one sperm penetrates the egg.
What is cleavage?
Zygote divides into many cells in a series of mitotic divisions
What happens to cytoplasm between mitotic divisions?
Gets subdivided into smaller cells
fats/sugars that feed organism
Small amount of yolk
Moderate amount of yolk
Large amount of yolk
Where does cleavage happen in a telolecithal egg?
On egg's surface
Lots of yolk is for animals that practice what development?
Straight into a mini adult
A little bit of yolk is for animals that practice what development?
Organism goes through a larval phase so it grows as it eats
Hollow ball of cells with a blastocoel in the middle
Dipoblastic Animals (2)
- 2 primary germ layers
- Incomplete gut
Tripoblastic Animals (2)
- 3 germ layers
- ecto-,endo-, mesoderm
Epithelium & nervous tissue
Muscles, organs, skeleton
Forms mouth or anus of animal
- Blastopore becomes anus
- Radial Cleavage
- Regulative embryo
- Blastopore becomes mouth
- Spiral cleavage
- Mesaic embryo
Outpocketing off of endoderm that lines archenteron
Mesoderm forms by splitting off of early germ layers
- Entire middle of animal fills with mesoderm
- Thin layer of mesoderm around edge of animal
- Segmented worms
- Outside is filled with mesoderm & a mesoderm line forms around and outside gut
Gastrulation patterns vary depending on-
Amount of yolk & phylogeny
Stem Cells (2)
- Adult- repair cells
- Embryo-differentiate germ layers
Union of gametes & exchange of genetic material
Positives of sexual reproduction (2)
- Genetic variation
- Distinct offspring
Negatives of sexual reproduction (4)
- Require time & energy
- Females only pass on half of genes
Why is genetic variation beneficial?
If there's a change in environment then offspring will survive
Dividing to form daughter cells/clones
Positives of asexual reproduction (4)
- No mate
- One parent
- Numbers increase quickly
- Saves time & energy
New individual from a single adult (cnidarians)
Adult splitting in two
Development of an egg without fertilization
What animals practice fragmentation?
What is the role of sperm in parthenogenesis?
Sperm is used to activate the egg but no fertilization.
Red Queen Hypothesis
Parasites and disease are rapidly evolving because reproduction=mutation
In the Red Queen Hypothesis, who do females mate with?
Females mate with males that have genes of a different immune system
Release of gametes directly into the water
- Can produce sperm & egg
- Have both reproductive organs
- Can be sequential or simultaneous
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