Module 9, lesson 3 reproduction3

Reproduction

Comparison of the 2 types

Sexual• 2 parents• Needs meiosis to occur• Variety among offspring

– More natural selection– Crossing over can give even

more variety

Asexual• 1 parent• Needs mitosis to occur• Can occur in an

environment where there are little organisms

• Offspring identical to parent– Less natural selection

Meiosis allows for Sexual Reproduction to have more variation due to:

Nondisjunction• Chromosomes fail to

separate during meiosis which allows for different chromosome numbers.

Crossing Over• A section of one

chromosome switches places with the same section from the other chromosome of the pair.

Bacteria mainly do asexual reproduction by binary fission.

However, they can exchange DNA which then counts as sexual.

Bacterial Conjugationwww.flickr.com/photos/ajc1/1103490291/

Conjugation by Paramecium

Paramecium join at the oral groove and exchange DNA.

Pollination

www.fs.fed.us/.../pollinators/birdsandbees.shtm

Sexual Reproduction

Male gamete= SpermFemale Gamete= Egg

Fertilized egg = Zygote

erin-moore.com/pages/06%20fertilization.htm

Animals

Animals can either do

– External Fertilization: Like a fish

Or

- Internal Fertilization: Like Animals