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TRANSCRIPT
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
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