ASEXUAL REPRODUCTION

VS. SEXUAL

REPRODUCTION

ASEXUAL REPRODUCTIONOne Parent RequiredDoes NOT Require Gametes (sex cells)Offspring produced by cell division.Offspring identical to Parent (Identical DNA)Several Different Types

Binary FissionBudding Regeneration/FragmentationVegetative PropagationSporulation

BINARY FISSIONOrganisms Divide in Half

2 Identical daughter cells produced.Daughter cells are half the parent’s size.Daughter cells grow and then divide into

two new identical cells.This occurs in bacteria.

BUDDINGSmall bud grows out of parent cell

Two different sized cells made (with identical DNA)

Bud breaks off and growsThis occurs in yeast and hydra

REGENERATIONRepair/ grow lost body parts

Left over cells divide to make more cellsOccurs in Lobsters, starfish, lizards

FRAGMENTATIONA single parent breaks into

parts that regenerate into whole new individuals.

VEGETATIVE PROPAGATION

Occurs only in plants (vegetative).New plants develop from the roots,

stems, or leaves of the parent plant.

SPORULATIONSpore Formation

• Spores are produced and each spore develops into offspring which are identical to parent

• Spores are surrounded by a tough coat to help them survive harsh environmental conditions.

• This occurs in fungi, green algae, molds and non flowering plants (e.g. ferns)

SEXUAL REPRODUCTION

Sexual reproduction is the production of offspring using gametes (sex cells). Requires two parents that each share ½ of the

genetic information.Offspring share the characteristics of each parent.

The cells of the offspring have two sets of chromosomes (one from each parent), so are diploid.

Haploid = half the number of chromosomes. Human haploid cells have 23 chromosomes

Diploid= 2 of every chromosome Human diploid cells have 46 chromosomes.

Results in offspring that have a variety of traits that are similar to the parents, but not exact copies!

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FERTILIZATIONInternally (inside)

The egg is fertilized by sperm inside the female

Mammals, birds, reptiles, insects, spidersExternally (outside)

The egg is fertilized by sperm outside the female

The female lays the eggs and then the male fertilizes them.

Fish and some amphibiansPlants and fungi (pollen and spores)

POLLINATIONpollen grains from the anther are transferred to

the stigma by the process of pollinationself pollination (plant pollinates its own eggs)cross pollination (pollen from one plant pollinates another

plants eggs)flowers are designed to lure insects to help

with the pollination processalso wind, animals, birds can transport pollen

SOME ORGANISMS DO BOTHmost plants that produce seeds (sexual

reproduction) can also reproduce asexually by things like cuttings or runnersthis gives them an advantage for survival sponges and hydra mosses

WHICH IS BETTER?IT DEPENDS!

Asexual Reproduction

advantages• does not require special

cells or a lot of energy• can produce offspring

quickly• in a stable environment

creates large, thriving population

disadvantages• limited ability to adapt• face massive die-off if

environment changes

Sexual Reproduction

advantages• lots of variation within a

species• able to live in a variety of

environmental settings• able to adapt to changes

in the environmentdisadvantages

• needs time & energy• produce small populations