Final Flashcards
Types of Asexual Reproduction
-Binary Fission: bacteria, amoeba -Budding- yeast - Spore Formation- fungi - Fragmentation- flatworms -Vegetative Reproduction - Parthogenesis (virgin birth)- some reptiles
Advantages of Asexual Reproduction
-efficient - don’t need to spend time finding a mate - all organisms can reproduce
Disadvantages of Asexual Reproduction
- lack of genetic diversity -all organisms respond same way to the environment - organisms lack the ability to adapt to changing environment
“Two fold cost of sex” hypothesis
- only one half of the population is suitable to give birth, the other half is useless
Advantages to sexual reproduction
-creates genetic diversity - genetic variation: gives at least some members of a population an opportunity to survive a deadly disease or adverse climactic scenario - DNA repair: there is an immediate large benefit of removing DNA damage by recombinational DNA repair during meiosis
Red Queen Hypothesis
- it takes all the running you can do to keep in the same places -means that a population as a whole needs to continuously adapt to keep up with conditions and parasites
Origin of Sexual Reproduction
Prokaryote- Protoeukaryote- last eukaryotic common ancestor (LECA)
Meiosis entails..
-Alteration of ploidy (diploid-haploid-diploid) -origination of gametes -mating type regulated transmission of organelle genomes
Alteration of Ploidy
-Increase in genome size and ploidy : more information to work with, , increase in the genome size favors experimentation- allows for positive selection and accumulation of favorable mutation
Origination of the gametes
Anissogametes (different gametes) and the recognition of ‘self’ vs. ‘non self’ is one of the key reasons for the origin of eukaryotic sex
Mating type- regulation of organelle genomes
-organelles such as mitochondria are only inherited from one sex - the rationale is that the fusion of gametes would generate diploid zygotes with twice the organelle-genome tally: this guards against “heteroplasmy” which is the presence of two or more different organelle genomes in the same organism
Types of Reproductive Processes
- Oviparous- female lay eggs which hatch outside the body (birds and fish) 2. Ovoviparous- give birth to live young which hatch from eggs inside the body (snakes, lizards, and amphibians) 3. Viviparous- give birth to live young which are nourished by contact between placenta and uterus (mammals)
Mammalian Reproduction Variations
- Induced vs. Spontaneous Ovulation - Delayed Fertilization (out of hibernation) - Delayed Implantation (Embryonic diapause) (bears, elephant seals, small carnivores, seals, sea lions) : males and females separate while foraging- copulation occurs when both sexes together on land during birth period. Two types: obligate and faculative - Spontaneous abortion: the tendency for female rodents to terminate their pregnancies following exposure to the scent of an unfamiliar male - Monozygotic Polyembryony: environmental control of gestation length - Menopause -Intrafollicular Fertilization
Endocrine Glands
-directly released into blood stream or lymph -ductless -Example: Anterior Pituitary
Exocrine Glands
- have ducts, secretes many types of substances: sweat, oil, wax, enzymes -Example: endometrial secretion of uterine milk
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