Chapter 46 Flashcards
Types of asexual reproduction
fission, budding, parthenogesis
Parthenogenesis
(lizards)
egss develop w/o fertilization
happens when environmental conditions are good (sexual reproduciton happens if they’re not)
Asexual Reproduction
Positives
- no partner needed
- no “sharing offspring (more own genes in next gen)
- easier to colonize new location
- if enironment constant and favorable, genetically-identical offspring well-suited to environment
- produce many offspring quicly
Asexual Reproduction
Negatives
- if environment is variable in space or time, lack of variation in offspring is disadvantageous
- an “evolutionary dead-end” if there is no way to introduce genetic variation
Origins of Sexual Reproduction
no one really knows why it evolved
likely evolved in the pre-cambrian era
Sexual Reproduction
Positives
- offspring genetically diverse
Sexual Reproduction
Negatives
- variation not advantageous if environment is good and constant
- need partner
- “share” offspring (only 50% of genes)
- Harder to colonize new location
Hermaphrodites
both male and female
earthworms
SRY Gene
codes for a transcription factor that up-regulates regulatory genes controlling formation of testes and production of testosterone
(determines if male)
Gameotogenesis
formation of gametes
gametes are produced by meiosis (produces haploid cells)
FSH and LH
Hormone
Target
Testes or Ovaries
TSH
Thyroid
ACTH
Adrenal Cortex
Prolactin
Mammary glands
MSH
melanocytes
GH
Liver, bones, and other tissues
Hypothalamus (sequence)
Neurosecretory cells of hypothalamus -> portal vessels -> hypothalamic releasing and inhibiting hormones -> endocrine cells of anterior posterior -> pituitary hormones -> different hormones
Steroid Hormones (lipids)
Estradiol, Testosterone
Endocrine disruptors
Hormonally active molecules in the environment
Antagonists
block the function of a hormone
DDE
from the metabolic breakdown of the pesticide DDT
binds to and blocks androgen receptors
Vinclozolin
- fungicide used on grapes in vineyards
- androgen antagonist
- reduces sperm production
- produces malformed genitalia
- transgenrational effect
Blocking of transcpription
methylation of DNA
Epigenetic inheritance
change in the control of gene expression is passes to next generation
Oogenesis
formation of eggs
DES (diesthylstilbestrol)
mimics estradiol
prescribed to maintain at-risk pregnancies
caused genital abnormalities and cancer in women exposed in utero
is an obesigen
represses Hoxa10 gene
Atrazine
- increase in hormone synthesis
- herbicide increases estrogen synthesis
- converts testosterone to estrogen = chemical
- one of the most widely used agricultural pesticides in U.S. to control broadleaf and weeds
- used primarily on corn, sorghum, and sugarcane, midwest most
- used to a lesser extent on residential lawns mostly FL, and SE
BPA
- makes individual more sensitive to natural hormones
- induces the production of receptors for estrogen
- affects methylation patterns
- Bispheonl A
- everywhere
fission, budding, parthenogesis
Types of asexual reproduction
(lizards)
egss develop w/o fertilization
happens when environmental conditions are good (sexual reproduciton happens if they’re not)
Parthenogenesis
- no partner needed
- no “sharing offspring (more own genes in next gen)
- easier to colonize new location
- if enironment constant and favorable, genetically-identical offspring well-suited to environment
- produce many offspring quicly
Asexual Reproduction
Positives
- if environment is variable in space or time, lack of variation in offspring is disadvantageous
- an “evolutionary dead-end” if there is no way to introduce genetic variation
Asexual Reproduction
Negatives
no one really knows why it evolved
likely evolved in the pre-cambrian era
Origins of Sexual Reproduction
- offspring genetically diverse
Sexual Reproduction
Positives
- variation not advantageous if environment is good and constant
- need partner
- “share” offspring (only 50% of genes)
- Harder to colonize new location
Sexual Reproduction
Negatives
both male and female
earthworms
Hermaphrodites
codes for a transcription factor that up-regulates regulatory genes controlling formation of testes and production of testosterone
(determines if male)
SRY Gene
formation of gametes
gametes are produced by meiosis (produces haploid cells)
Gameotogenesis
Target
Testes or Ovaries
FSH and LH
Hormone
Thyroid
TSH
Adrenal Cortex
ACTH
Mammary glands
Prolactin