Cells - The Basic Unit of Life The characteristics of an organism in terms of a combination of inherited traits and reproduction.

What are we trying to accomplish? Recognize that an individual organism does not live forever, therefore reproduction is necessary for the continuation of every species and traits are passed on to the next generation through reproduction. Describe that in asexual reproduction all the inherited traits come from a single parent. Describe that in a sexual reproduction an egg and sperm unite and some traits come from each parent, so the offspring is never identical to either of its parents.

Why is reproduction important? Organisms do not live forever. If organisms did not reproduce everything would be extinct. Reproduction allows our traits to be passed on to the next generation.

Traits that “Run in the family.” Hair color A tendency to develop diseases, such as diabetes and some forms of cancer. Personality traits, such as shyness. Can you think of other traits that may be passed down?

Two Kinds of Reproduction Asexual Reproduction Sexual Reproduction

Asexual Reproduction What is it? One Makes Two

Asexual Reproduction In asexual reproduction, only one parent cell is needed for reproduction. The internal structures of the cell are copied by a process know as mitosis. The parent cell then divides, producing new cells that are exact copies of the parent cell. Most of the cells in your body divide this way.

5 forms of asexual reproduction Budding Binary Fission Vegetative propagation Parthenogenesis Fragmentation

Budding Occurs when offspring develops from a portion of the parent and pinches off to live independently. (i.e. Hydras - plants that live in freshwater ponds and streams)

Binary Fission Occurs when a single-celled organism reproduces by splitting in two (i.e. Amoeba)

Vegetative propagation Occurs when new plants are produced from sections of parent plants that are cut off (i.e. Geraniums, willow trees,and spider plants.)

Parthenogenesis Occurs when certain animals produce eggs that develop directly into offspring without fertilization (insects, reptiles, fish)

Fragmentation Occurs when certain animals grow from a separate parent animal (star fish, flat worms)

Sexual Reproduction Two Makes One

Sexual Reproduction In sexual reproduction, two parent cells join together to form a new individual. The parent cells (aka sex cells) are different from ordinary body cells. Human body cells have 46 chromosomes (or 23 pairs). Male sex cells are called sperm. Female sex cells are called eggs.