reproduction! purpose: create offspring for the continuation of your species

Reproduction!

Purpose: Create offspring for the continuation of your species

Asexual (clones)• Only 1 parent needed• made by prokaryotes, protists!

– Binary fission & Mitosis: photocopy all DNA & rip cell in half

– Circular DNA in prokaryotes

3 different examples of

budding

Yeast

Hydra

Spider Plants

Sex: why bother?!?!• Plants, animals, fungi…

–Cell still duplicates DNA first–But, meiosis rips the cell apart TWICE

• creates gametes (eggs & sperm) with genetic variety–crossing over and independent assortment

• Diploid (2n) cell Haploid (n) cells

Locations of meiosis in tulip and lily (hermaphrodite flowers)

Ovaries make eggs at flower base

Anthers produce pollen (sperm)

Seed to fruit… the next generation!

• Seed’s energy comes from stored starches• It knows which way to grow = TROPISMS• Photosynthesis picks up once above ground

Figure 46.8 Reproductive

anatomy of the human male

Testes produce hormones and create sperm

Human Spermatogenesis

• Starts at puberty (~11-15) • Testes produce sperm and testosterone,

(hormone responsible for male characteristics)

• Millions made daily!• Quantity over quality• ALL 4 HAPLOID GAMETES SURVIVE

1) Releases egg & hormones

2) Fertilization occurs (= zygote)

3) Implantation; placenta attaches here

Human Oogenesis• Primary eggs made while in womb!• 4 Hormones prepare for fertilization

Ovaries make hormones develop nutrient-rich uterus lining Ovulation releases mature egg

• If no fertilization, lining dissolves (menstruation/”period”)

• Can get pregnant 5 days around ovulation!– Sperm live 5 days inside womans body– Eggs only viable for 1 day

Fertilization = merging of 2 complete sets of DNA

• What organelle will sperm require a ton of since they have to swim a lot?

• http://science.howstuffworks.com/life/human-biology/human-reproduction10.htm

Ovary Fallopian Tube Uterus

Figure 46.18 Mommas belly growing Cool Sonogram Fetal movie 4 min baby moving kicking in belly

Embryo Fetus

Identical Twins (monozygotic)

Fraternal twins (dizygotic)

• 2 eggs released at same time• Both fertilized with sperm• Not identical babies!

Conjoined Twins

Pregnancy

• Woman ovulates sex (~6 day window!)• Fertilization: sperm(n) & egg(n) DNA unite• Diploid zygote divides 2 4 8 cells, etc• Ball of stem cells implants itself into uterine

lining• Embryo: Heart beats, brain forms• Fetus obtains nutrients through placenta &

umbilical cord (11 weeks birth)• Uterus contracts… baby is born… more

contractions… placenta is released

Delivery is initiated by hormone spikes: a positive feedback loop

How do other organisms reproduce?

C. elegans roundworms

• Hermaphrodites (XX) and males (XO)

Gymnosperm reproduction

Frog Reproduction