Asexual and Sexual Reproduction

I can identify the difference between sexual and asexual

reproduction.

QW#6 What is the difference between sexual and asexual

reproduction?

State Standards

• 6th Grade Life Science 4 Recognize that an individual organism does not live forever; therefore

reproduction is necessary for the continuation of every species and traits are passed onto the next generation through reproduction

• 6th Grade Life Science 5 Describe that in asexual reproduction all of the inherited traits come from one

single parent

• 6th Grade Life Science 6 Describe that in sexual reproduction an egg and sperm unite and some traits come from each parent, so the

offspring is never identical to either of its parents

• 8th Grade Life Science 1 Describe that asexual reproduction limits the spread of detrimental characteristics through a species and

allows for genetic continuity

Reproduction

• There are about 1.5 million different types of living species known Some reproduce

sexually, asexually, or both

Purpose of Reproduction

• To make sure a species can continue. Definition: Reproduction is the process by

which an organism produces others of its same kind.

Asexual Reproduction

• Asexual reproduction= is a process that involves only one parent and produces offspring that are identical to the parent

• Advantage- asexual reproduction limits the spread of detrimental characteristics

• Disadvantage- is asexual reproduction the organism can not adapt to change in the environment

1st Type of Asexual Reproduction

• Budding is another form of asexual reproduction where a growth of a copy of the adult buds from the adult itself until the bud breaks off and becomes its own organism This happens in yeast Very Common in Plants

Budding Example

• Fungi are eukaryotic organisms. They are also saprophytic (this means they

get their food from dead organic matter) Fungi can be multicellular or unicellular (yeast) Some are parasitic (ringworm, athlete’s foot)

Budding Example

• Yeast Yeast are unicellular fungi that reproduce by

budding• Budding occurs rapidly under ideal conditions

(mixed with sugar and water in warm temps)

2nd Type of Asexual Reproduction

• Fission (Binary) is another form used by some single-celled organisms such as bacteria or amoeba

• Becoming two by division of the complete organism. The organism divides by mitosis to make a

new cell

Protists

• Protists are single-celled eukaryotic organisms Protozoans are named b/c

they are “animal-like” and actually resemble eukaryotes in the way they work than prokaryotes like bacteria

• Ex: Paramecium can reproduce asexually by fission or sexually by conjugation

3rd Type of Asexual Reproduction

• Regeneration

• The ability to restore lost or damaged tissues, organs or limbs.

• It is a common feature in invertebrates, like worms and starfish.

Sexual Reproduction

• Asexual Reproduction – genetic material of one individual is passed onto the next

• Sexual Reproduction – genetic material of two individuals are combined In sexual reproduction an egg and sperm unite and

some traits come from each parent, so the offspring is never identical to either of its parents produced in meiosis

Combining two individual’s genes creates variability in the population (an advantage in a changing environment)

Sexual Reproduction

• When a zygote is formed, it divides by mitosis creating 2, 4, and 8 celled stages and then forms a mass of cells called a morula

• Further mitosis creates a hollow ball of cells called a blastula (~1,000 cells)

• Subsequent divisions create tissue layers in the gastrula• Gestation (the period of time it takes for an embryo to

grow and change into an individual) can take no more than 3 weeks for a chicken but up to 2 years for an elephant Humans ~ 9 months

Sexual Reproduction

• Look at prepared slides of the following stages of starfish development: Egg 2-cell stage 4-cell stage 8-cell stage Morula Blastula Gastrula