ASEXUAL REPRODUCTION

• There are many forms of asexual reproduction

• All have 3 things in common• Only one parent involved• All offspring are genetically identical to the parent

– This means they contain identical DNA

• The cell(s) that produce the offspring are not specialized for reproduction

Methods of asexual reproduction

**Remember that the parent DNA is first duplicated so that** the offspring receives an identical copy

Binary Fission• Organism splits into 2 equal-sized offspring• Occurs primarily in single celled organisms

– Is the usual method of reproduction for bacteria and protists

• http://www.youtube.com/watch?v=K0ZP8VtxUZ0

Budding• Offspring begins as a growth (called a bud)

on the parent• Once bud has developed to point where can

survive on own, it detaches• Occurs in both single and multi-celled

organisms• Offspring is not physically identical to

parent, but is genetically identical

http://www.youtube.com/watch?v=489CSop00sY

Spore Formation

• Organism produces spore cells • Cells that are some-what specialized for reproduction

• Spores are spread by the elements (wind, water, etc.)

• If a spore lands in a favourable environment it will develop into a new organism.

http://www.youtube.com/watch?v=VWgm322uKWI&playnext=1&list=PL92A4B063B588C056

Fragmentation

• Pieces (fragments) of the parent body break off

• The fragments then grow into whole, new organisms

• Eg. Starfish and flatworms

• http://www.youtube.com/watch?v=f7cXeWxxfD4

Vegetative Reproduction

• Occurs only in plants• Special stems are sent out• Offspring emerge from these stems at

specific intervals• Stems travel on the surface runners• Stems travel underground rhizomes• Eg. Spider plants

Outcome of asexual reproduction

• Clone – identical offspring produced by

asexual reproduction• How could having populations of entirely

identical organisms be beneficial?• How could it be harmful?

Human Assisted Cloning• Humans use all the asexual cloning methods in order to

produce desired results with organisms. This is done in several ways:• Reproductive cloning - purpose is to produce a genetic duplicate of an existing or

dead organism. Steps involved:

1. Remove nucleus from an egg cell

2. A mammary gland cell is removedfrom an adult female

3. Electricity fuses mammary and egg cell

4. Fused cell begins dividing

5. Dividing embryo is inserted intosurrogate mother

Human Assisted Cloning• Therapeutic cloning - purpose is to correct health problems

– Very important to therapeutic cloning are stem cells - cells that can become different types of cells

– Stem cells can be used to replace cellsdamaged from injuries or disease

– Diabetes, spinal injuries, Parkinson’sdisease are only a few that canbenefit from stem cell therapy

– Controversial because the beststem cells are from embryos whichare destroyed when harvesting cells

Mouse Stem Cells

Review Questions

Complete the Check Your Understanding questions page 183 #1-14

Complete the Chapter Review page 184-185#1-26

Oysters are a major part of the diet of starfish. Because of this, people who catch oysters for a living used to try to kill starfish by cutting them up and throwing them back into the sea. Why might this practice not reduce the numbers of starfish?