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Asexual vs. Sexual Reproduction

Modified from: www.wayzata.k12.mn.us/ems/images/stories/academics/7th%2520Grade%2520Gold/Corens/asexual_vs._sexual_reproduction.ppt

Asexual reproduction

A form of reproduction which does not involve meiosis or fertilization. Asexual reproduction = one parent. The primary form of reproduction for single-celled organisms such as archaea, bacteria, and protists.Many plants and fungi reproduce mostly asexually as well.

Sexual Reproduction

Results in increasing genetic diversity of the offspring. Characterized by two processes:

meiosis, halving of the number of chromosomesfertilization, combination of two gametes and the restoration of the original number of chromosomes

During meiosis, chromosomes usually cross over = genetic recombination.Primary method of reproduction for the vast majority of visible organisms, including almost all animals and plants.

Binary Fission

• Asexual• Cell splits and replicated DNA goes with each part

• Prokaryotes, Bacteria

• + Fast and easy• - Everybody has the same DNA

Bacterial Conjugation

• Asexual, “Sexual” • A bacteria shoots

out a tube and sends a piece of its DNA to another bacteria

• Bacteria• + Mixes DNA• - “Parent” loses a

little piece of DNA

Fragmentation/ regeneration

• Asexual• Body of parent

breaks and produces offspring

• Fungi, moss, sea stars, planarian

• + Easy• - Parent broken,

same DNA

Fragmentation/ regeneration

Moss

Budding

• Asexual• Offspring grows out

of parent• Yeast, hydras• + Fast, somewhat

easy• - Same DNA

Spore Formation

• Spore Formation – spores = small specialized cells that contain a nucleus and cytoplasm surrounded by a thick outside wall which protects the spore. Under the right conditions the spore can rise to a new organism. Found in bacteria, molds, yeast, mushrooms, mosses, ferns and some protozoans.

Spore formation

Vegetative Reproduction

• Bulb = Short underground stem surrounded by thick leaves. Contain stored food. As the plant grows it produces new bulbs which will grow into new plants. Tulips, onions, and lilies.

• Tuber = enlarged part of an underground stem that contains stored food. Potatoes are tubers. “Eyes” = tiny buds that can form a new potato plant. How you plant potatoes. Great potato famine.

• Runner or stolen = horizontal stem above the ground with buds. If a bud touches the ground it will form roots and stems and start a new plant. Strawberries.

Sexual Reproduction

Pollination

• Sexual Reproduction• Pollen is delivered to

female part of plant• Flowering plants• + Plants don’t have

to move, mixes DNA• - Need external

source for pollination to take place; wind, bee, bat, butterfly etc.

Pollination

Sexual Reproduction

• Sexual Reproduction• DNA from 2

individuals merge to form one

• Animals, Plants• + Diverse DNA• - Takes a long time,

2 individuals needed

Sexual Reproduction