On a blank piece of paper, write down everything that is in RED.

On your textbook, look under “asexual reproduction”, and “sexual reproduction” on the index and read pages listed.

Methods ofMethods of

Reproduction:Reproduction:

Sexual and AsexualSexual and Asexual

Asexual Reproduction: • requires only 1 parent • offspring are exact copy of the parent: a clone• No genetic variety in the population: organisms

are “copies” of the original.

Types of asexual reproduction:

• Binary fission• Budding• Fragmentation/Regeneration• Spore formation• Parthenogenesis

Assexual rep. 2.4 min

Binary fission

• divide into two equal halves • Single cell organisms• examples: Amoeba,

paramecium, euglena• binary fission bacteria

• When conditions are good, such as plenty of water, food, right temperatures, etc., binary fission is a very effective way of producing many, many offspring.

• For example, the cell of a Paramecium can divide, grow, and divide again in the space of 8 hours.

Budding

offspring

Cactus Budding

• an offspring grows out of the body of the parent.

• Offspring smaller than parent cellbudding yeast

Hydra Budding yeast

Fragmentation/Regeneration• piece of parent organism produce an offspring.• Plant cuttings: Some plants can grow from

cutting them up and replanting them.» coral reproduction

Pieces of coral broken off in storms can grow into new

colonies.A new starfish can grow from

one detached arm.

Green plants are quite sophisticated in their methods of asexual reproduction. Offspring may be produced by runners,

bulbs, rhizomes or tubers.

runners Suckers/buds tubers

Spore Formation

• spores grow into multicellular individuals• Examples: Algae, fungi• mushroom spores

Parthenogenesis (natural cloning)• Eggs develop without fertilization.• Examples: invertebrates, several fish,

amphibians, reptiles, many plants. • no known cases of parthenogenesis in mammals.• comodo dragon

Sexual Reproduction

• Needs 2 parents: – male and female – Gametes (sex cells: egg and sperm)

• Egg joins sperm to form zygote (new organism)• Offspring are different from parent • Diversity because of exchange of genetic

material in meiosis• Genetic variation improves survival (evolution)

Sexual Reproduction:

Types of sexual reproduction:

• Pollination• External Fertilization• Internal Fertilization/Copulation• Hermaphroditism

• pollen attaches to female egg, found in stigma.

• Pollen is male sex cells in plants. Found in flower’s anthers.

Pollination

External Fertilization• requires a medium (water): sperms swim to

the egg cell. • fish and amphibians• females lay the eggs in the water and the

male squirts the sperm in the same area.oscar fish oscar fry

Internal Fertilization• Fertilization occurs within the female.• mammals, insects, birds, reptiles.

– Mammals have live births– Insects, birds, reptiles, lay eggs

Hermaphroditism

• organisms have both reproductive organs: ovarian and testicular tissue

Example: snails, starfish, sand dollar, worms, seahorses, grouper, sea bass

Sexual vs. Asexual Reproduction• Asexual

– Mitosis generates cells– Somatic cells (ex.: skin cells) or unicellular organisms– offspring that are genetically identical to the parent– Needs 1 parent.

• Sexual – Meiosis generates sex cells– Sex cells or gametes (sperm and egg)– offspring is genetically different from parent – Needs 2 parents (male and female)

Asexual ReproductionAdvantages:1. large number of offspring2. less energy 3. No sex organs or opposite sex partners

Disadvantages:1. No genetic variation 2. Less likely to survive changes in environment (evolution)3. No protection of young decreases survival

Sexual ReproductionAdvantages:1. genetic diversity 2. More chances to survive changes in environment (evolve)3. Caring for young increases survival

Disadvantages:1. reproduce less frequently & have fewer offspring 2. More energy to protect and nurture offspring 3. Non-nurturers leave offspring vulnerable to predators