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