Eukaryotic Life Cycles

BIOL 1407

Life Cycles

• Asexual Reproduction

• Sexual Reproduction– Gametic meiosis– Zygotic meiosis– Alternation of Generations

Asexual Reproduction• Watch Video #4, binary fission in Paramecium• http://www.microscopyu.com/moviegallery/pondscum/protozoa/paramecium/t1/paramecium04.html• Photo Credit: Courtesy of Richard Allen @ http://www5.pbrc.hawaii.edu/allen/

Gametic Meiosis

• Diploid multicellular organism

• Produces gametes by meiosis

• Gametes = only haploid stage

Gametic Meiosis

• Gametes always fuse to form zygote

• Zygote grows into diploid multicellular organism

Zygotic Meiosis

• Haploid multicellular organism

• Produces gametes by mitosis

• Gametes always fuse to form zygote

Zygotic Meiosis

• Zygote meiosis haploid spores

• Zygote = only diploid stage

• Spores grow into haploid multicellular organisms

Alternation of Generations

• Two generations:– Multicellular

haploid organism– Multicellular diploid

organism– Life cycle

alternates between the two

Alternation of Generations

• Multicellular diploid organism

• Produces haploid spores by meiosis

Alternation of Generations

• Spores grow into haploid multicellular organisms

• Haploid multicellular organism produces gametes by mitosis

Alternation of Generations

• Gametes always fuse to form zygote

• Zygote grows into diploid multicellular organism

Question: Which Type?

The End

Unless otherwise specified, all images in this presentation came from:

Campbell, et al. 2008. Biology, 8th ed. Pearson Benjamin Cummings.