Asexual and Sexual Reproduction Objective: Students will explain asexual (binary fission, budding,...

Asexual and Sexual Reproduction

Objective: Students will explain asexual (binary fission, budding, vegetative, mitosis) and sexual

reproduction (angiosperms, mammals)

Asexual ReproductionProcess by which a single parent

reproduces by itself without the joining of gametes (reproductive cells)

Sexual ReproductionProcess by which male and female gametes unite to produce the first cell

of a new organism

Asexual ReproductionExamples:

– Spore Formation– Binary Fission– Vegetative

Reproduction– Regeneration– Budding– Mitosis

• Does not involve meiosis or the joining of haploid gametes

• Cells are diploid (2N)• Produces offspring

that are genetically identical to the parent

Spore Formation• Spores - (“mummified” bacterium) – dormant non-reproductive body

• Protective coating encase key parts of the bacterium

• Spores formed by certain bacteria in response to harsh environmental conditions

• Spore able to survive for weeks (even years) through drought, heat, even radiation

• When conditions become more favorable, bacterium “comes to life” (transforming from a spore back to a cell)

• Also produced by certain fungi, algae, and non-flowering plants.

Binary Fission (p. 475)

• One cell splits into two cells

• Offspring are genetically identical to parent

• Occurs in Prokaryotes (organisms w/out a nucleus) i.e. Bacteria

Vegetative Reproduction

• Also called vegetative propagation

• Process by which new plant "individuals" arise or are obtained without production of seeds or spores (without sexual reproduction)

• produce new plants from existing vegetative structures by cutting from stems, leaves, roots, parts of leaves and thick canes

Budding• Formation of a new

organism by the protrusion of part of another organism.

• Very common in plants and fungi (vegetative Reproduction), but may be found in animal organisms, as well.

• Shortly, the new organism will break away from parent and live independently

• New organism is genetically identical to the primary one (a clone)

A new hydra budding from an existing hydra

Budding Yeast

Regeneration

• Form of tissue repair and/or healing

• Ability to regrow lost limbs, severed nerve connections, damaged tissues and organs

• Example of plant regeneration - when grass is cut, the blade regrows

Starfish

Planaria

Mitosis

Mitosis produces two cells with the same number of chromosomes as the parent cell. Mitosis of a diploid cell (2n) produces two diploid daughter cells.

Sexual Reproduction

• Process by which male and female gametes unite to produce the first cell of a new organism

• Involves the joining of haploid gametes that have been produced by meiosis

• Offspring are not genetically identical to either parent

Sexual Reproduction

In Mammals• Reproduce by internal

fertilization (male deposits sperm inside the reproductive tract of the female – where fertilization occurs)

• Meiosis used to produce the gametes: sperm and egg

In Angiosperms (Flowering Plants)

• Meiosis used to produce the spores -- which in time will produce the gametes (pollen -male; egg - female)

• Reproduce by cross-pollination (transfer of pollen to female reproductive structure)

Angiosperms(CH 24-1, pp. 612-621)

• Flowering plant that produces seeds within an ovary that develops into a fruit; therefore, the seeds are covered

• Most abundant plant on Earth• Terrestrial and lack locomotion

– Poses a problem– Gametes are delicate single cells. For two plants

to cross-pollinate, there must be a mechanism for the two gametes to reach each other safely

Reproductive Parts of a Flower

• The flower is the reproductive organs of angiosperms• Stamen - male organ that produces pollen (consists of the anther &

filament)• Carpel (also called pistil) – female organ that produces egg• Other parts of the flower

– Sepal – green (resemble leaves) protect the flower while it’s developing– Petal – often brightly colored – attract pollinators (i.e. insects) to flower

• Most angiosperm flowers contain both the stamen and pistil

Active Artphschool.com

webcode cbp-7241(click the link to go to activity)

Answer the questions.

• What is the function of flowers?

• An angiosperm is a plant that produces seeds that are enclosed in a _______________.• The male structure of a flower is known as the _______________.• The female structure of a flower is known as the _______________ .• List the structures that make up the stamen.

• List the structures that make up the carpel.

• Describe the function of petals on a flower.

• Where does meiosis take place?

• Where does pollination take place?

Life Cycle of an Angiosperm