 Sexual Reproduction – type of reproduction in which the genetic materials from two different cells combine, producing an offspring  Sperm – male sex cell  Egg – female sex cell  Fertilization – joining of the sperm and egg cell  The new cell that forms is called a zygote.

 Organisms that reproduce sexually make 2 kinds of cells- body cells and sex cells (gametes -sperm & egg)  Diploid cells – cells that have a pair of chromosomes; divide by mitosis (full # of chromosomes)  ex. body cells  Different Organisms have different numbers of chromosomes.  Ex: Humans have 46 chromosomes.(23 pairs)  Homologous chromosomes – pairs of chromosomes that have genes for the same trait arranged in the same order

 Sex cells are Haploid – only have one chromosome from each pair; divide by meiosis (half the # of chromosomes)  ex. sex cells (sperm and egg)

 Meiosis – process by which one diploid cell divides into four haploid cells; occurs in the formation of sex cells  Meiosis is important because:  It ensures the correct number of chromosomes in offspring ex. sperm (23) + egg (23) = human (46)  creates more genetic diversity by producing haploid cells.

 Starts as diploid cell  Body cells  1 division of nucleus  Produces 2 daughter cells  Diploid daughter cells  Used for growth and repair of cells  Starts as diploid cell  Reproductive cells  2 divisions of nucleus  Produces 4 daughter cells  Haploid daughter cells  Used to produce sex cells

 Advantages  Genetic Variation offspring inherit half their DNA from each parent helps with adaptations to changing environments  Selective Breeding breeding species with desirable traits ex. dog breeding, farming  Disadvantages  Time and Energy development of sex cells finding a mate Exposure to predators, disease, or harsh environmental conditions

 Asexual reproduction – one parent organism produces offspring without meiosis and fertilization  offspring are genetically identical to parent (clones)

 Fission  simple cell division in prokaryotic (bacteria) cells  Mitosis  simple cell division in eukaryotic cells  Budding  a new organism grows by mitosis on the body of its parent ex: hydra

 Animal Regeneration  offspring grows from a piece of its parent  Many animals can regenerate damaged or lost body parts. This is not reproduction; new individuals are not produced.  Vegetative Reproduction  offspring grow from a part of a parent plant  Cloning  A type of asexual reproduction developed by scientists and performed in laboratories.  production of an identical individual from a cell, or cluster of cells, taken from a multicellular organism  The clone is a genetic copy of the parent

 Advantages  no mate required  Enables some organisms to produce a large # of offspring  Disadvantages  little genetic variation which can decrease an organism’s chance of surviving if the environment changes.  more likely to suffer mutations