SEXUAL Reproduction TWO parents, offspring is genetically different from either parent - Adds variation to a species MEIOSIS – produce gametes that have half the number of chromosomes so that two parents can contribute to the offspring AND still maintain the chromosome number of that species!!! Gametes fuse during FERTILIZATION Fertilized egg-ZYGOTE-undergoes rapid mitosis and differentiation to become-> an EMBRYO
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SEXUAL Reproduction TWO parents, offspring is genetically different from either parent - Adds variation to a species MEIOSIS – produce gametes that.
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SEXUAL Reproduction TWO parents, offspring is genetically different
from either parent - Adds variation to a species
MEIOSIS – produce gametes that have half the number of chromosomes so that two parents can contribute to the offspring AND still maintain the chromosome number of that species!!!
Gametes fuse during FERTILIZATION Fertilized egg-ZYGOTE-undergoes rapid
mitosis and differentiation to become-> an EMBRYO
HUMAN Reproduction and Development
Have INTERNAL FERTILZATION Fully INTERNAL DEVELOPMENT, where
the placenta and umbilical cord maintain the embryo inside the uterus
After Nine Months (40 weeks) GESTATION – fert to birth The placenta is no longer efficient
enough to maintain the fetus, so it’s time for her or him to get outta there !
mitosis
zygote
Putting it all together…
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egg
sperm
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meiosis 4623
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fertilization mitosis &development
meiosis fertilization mitosis + development
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gametes
Fertilization
Twins
Identical – ONE sperm + ONE egg Cells split apart in EARLY stages of cleavage SAME DNA – MUST be SAME Gender
Fraternal – TWO sperm + TWO eggs No more closely relate than any two siblings Can be girl/girl, boy/boy, OR boy/girl Different DNA
Types of Cells
Different cells have different structures/shape and therefore different functions because they make different proteins because they have different genes turned “ON”
Placenta - Food & gases diffuse across blood vessels – with NO mixing
of blood
Birth/Labor – it’s hard work
1. Dilation – opening of cervix to 10 cm Usually the longest phase
2. Expulsion – pushing the baby out 3. Placental stage – placenta is
expelled from the uterus; also called the “afterbirth” Must come out AFTER the baby
HORMONES and the Ability to Reproduce
Hormones direct the changes that occur during development and growth
Begin maturing of egg and production of sperm at PUBERTY, usually in the early teens.
Wanes (lessens) as humans age Females cease menstruation at
MENOPAUSE, after age 50 Males continue to produce sperm
throughout lifetime
Sperm production Sperm delivered to female
Male reproductive system
seminiferous tubules
Male reproductive system
Testes & epididymis sperm production &
maturation Glands
seminal vesicles, prostate, bulbourethal
produce seminal fluid nutrient-richmeiosis
Male reproductive system Testicles - testes & epididymis