Asexual Reproduction

Sexual vs. Asexual Reproduction Asexual Reproduction Sexual Reproduction Produce offspring Genetically identical offspring Genetically unique offspring 2 parents 1 parent

Types of Asexual Reproduction Fission (often called binary fission) Mitotic cell division (mitosis) Budding Animal Regeneration Vegetative Reproduction Cloning

Binary Fission – Asexual reproduction in prokaryotic cells DNA molecule is copied Each copy attaches to the cell membrane. Cell grows longer pulling the copies of DNA apart. Cell membrane pinches inward toward the middle of the cell. Cell splits and forms to identical daughter cells.

Binary Fission vs. Mitosis

How Many Bacteria Cells? A bacteria cell that divides once per hour will produce how many cells in 24 hours? 16,777,216 !!!!! Many divide even faster and can produce billions in just 12 hours.

Budding A new organism grows by mitosis and cell division on the body of its parent. When the bud becomes big enough, it can break from its parent and live on its own. Genetically identical to parent. Yeast and Hydra

Regeneration Offspring grows from a piece of its parent. sea stars, sea urchins, sea cucumbers sponges planarians

Vegetative Reproduction Offspring grow from a part of a parent plant. Involves structures such as roots, stems, and leaves of the plant. strawberries, raspberries, potatoes, and geraniums

Cloning A type of asexual reproduction performed in a laboratory Produces identical individuals from a cell or from a cluster of cells. Often used to make copies of organisms with desirable traits.

Plant Tissue Culture Desirable traits can be copied. A greater number of plants can be produced more quickly than by vegetative reproduction. It can be used to reproduce plants that have been infected with a disease.

Cloning of Dolly The Sheep Scientists used a process called “somatic cell nuclear transfer” or SCNT.

Which sheep (X or Z) is Dolly genetically identical to? Dolly is genetically identical to sheep X because the DNA used to clone her came from sheep X. Sheep Z provided the egg cell (DNA removed) and served as the surrogate mother. Notice how Dolly is all white like sheep X, while sheep Z has a black head.

Regardless of the type of asexual reproduction...

Advantages of Asexual Reproduction Organisms can reproduce without a mate. Organisms rapidly produce a large number of offspring.

The efficiency of asexual reproduction comes at a cost… Asexual reproduction does not produce genetic variation. Genetic variation gives organisms a better chance of surviving if the environment changes. If harmful mutations occur, they will be passed to asexually reproduced offspring.

Why is genetic variation so important? In the example of crabgrass, if a certain weed killer can kill the parent plant, then it can kill all the crabgrass plants None will be resistant