Key Idea #16 All organisms have a life span and must reproduce in order to continue the species.

Reproduction allows the genetic material of living

things to be passed from generation to generation.

is required for the survival of a species. includes two types:

– sexual– asexual

Asexual Reproduction

Advantages: only one parent is needed offspring are genetically identical to parent can produce large numbers of offspring

Disadvantages: no genetic variety because offspring are genetically

identical to the parent since organisms are identical, the species can’t adapt

to a changing environment

Types of asexual reproduction include: runners bulbs tubers budding binary fission fragmentation regeneration cloning

FYI: Fragmentation and Regeneration A type of asexual

reproduction found in less evolved animals.

When the parent body breaks into pieces, each piece can grow into a new organism that is identical to the parent.– starfish, planaria

http://images.google.com/imgres?imgurl=http://image.tutorvista.com/content/reproduction/planaria-regeneration.jpeg&imgrefurl=http://www.tutorvista.com/content/science/science-ii/reproduction/asexual-reproduction.php&usg=__RTk4xJj77XukAzKY23f81XPmc1o=&h=371&w=415&sz=16&hl=en&start=28&um=1&itbs=1&tbnid=AO9LlKVsW0u0XM:&tbnh=112&tbnw=125&prev=/images%3Fq%3Dregeneration%2Band%2Bfragmentation%26ndsp%3D20%26hl%3Den%26sa%3DN%26start%3D20%26um%3D1

http://web.mit.edu/neuro/planaria.html

Sexual ReproductionAdvantages: Genetic variety

• offspring are genetically similar to their parents• both parents contribute 50% of the offspring’s genetic

material.

Organisms have a greater chance of adapting to environmental changes

learn.genetics.utah.edu

Sexual Reproduction

Disadvantages: Two organisms must be involved. Some genetic combinations can negatively affect the

survival of some species by passing on diseases and genetic defects.

Genetic defect examples: (see book pages 120-123)

– Cystic Fibrosis – Sickle-Cell Disease – Hemophilia– Down Syndrome

What about fraternal and identical twins?

FYI: Fraternal Twins are produced when two separate sperm cells

fertilize two different egg cells by sexual reproduction.

are not identical because they have different DNA (chromosomes and genes)

http://www.womenshealth.gov/pregnancy/you-are-pregnant/twins-multiples.cfm

FYI: Identical Twins

are produced after one sperm cell fertilizes an egg cell by sexual reproduction and the fertilized egg divides into two fertilized egg cells by asexual reproduction.

are identical because they have identical DNA (chromosomes and genes).

http://www.womenshealth.gov/pregnancy/you-are-pregnant/twins-multiples.cfm

Some organisms reproduce in more than one way……

Bacteria reproduce

Asexually genetic material is duplicated before the cell divides

resulting in two daughter cells that are genetically identical to each other.– Note: a disadvantage is antibiotics will kill all bacteria

Sexually genetic material is transferred from one cell to

another cell forming one new bacteria cell that is genetically different from the parent cells – Note: An advantage is antibiotic resistance in offspring.

http://biology.about.com/od/bacteriology/a/aa080907a.htm

Plants reproduce sexually through

pollination and fertilization

asexually through production of runners, tubers, regeneration, bulbs, cloning, etc…

Life Cycle of the Flowering Plant