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…

23

2346

egg

sperm

46

meiosis 4623

23

fertilization mitosis &development

meiosis fertilization mitosis + development

46

46

46

46

46

4646 46

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

produces sperm & hormones - testosterone Scrotum - 1-2 degrees cooler

sac that holds testicles outside of body Epididymis

where sperm mature Vas deferens - vasectomy vs. castration

(neutering) tubes for sperm to travel from testes to penis

Prostate, seminal vesicles, Cowper’s (bulbourethal) glands nutrient rich fluid to feed & protect sperm

Female reproductive system

womb - muscle

fertilization

implantation

Female reproductive system

(oviduct)

womb

Birth canal

Female reproductive system Ovaries – follicle and corpus luteum

produces eggs & hormones – estrogen & progesterone

Uterus – womb – implantation occurs nurtures fetus; lining (endometrium) builds up

each month Fallopian tubes - oviducts; fertilization occurs

tubes for eggs to travel from ovaries to uterus Cervix

opening to uterus, dilates 10 cm for birthing baby Vagina – sperm deposited

birth canal for birthing baby