Sexual vs. Asexual Reproduction

L.HE.M.2 Reproduction

I can describe how characteristics of living things are passed on to offspring through asexual and sexual reproduction.

I can compare and contrast the advantages and disadvantages of asexual and sexual reproduction.

Sexual ReproductionA type of reproduction in which the genetic materials from

two different cells combine, producing an offspringCan be INTERNAL or EXTERNALThe cells that combine are called gamates

Female – eggMale – sperm

Fertilization: an egg cell and a sperm cell join togetherA new cell is formed and is called a zygote

Advantages: Sexual Reproduction

Diverse offspring: genetic variation among offspringHalf of the DNA comes from femaleHalf of the DNA comes from male

Due to genetic variation, individuals within a population have slight differencesPlants – resist diseasesTraits can develop to resist harsh environments

that allows an organism survive

Advantages: Sexual Reproduction

Selective BreedingUsed to develop many types

of plants and animals that have desirable traits

Agriculture/Farming: better plants, larger animals

Desirable pets

Disadvantages: Sexual Reproduction

Time and EnergyOrganisms have to grow and develop until they are old

enough to reproduceSearch and find a mateSearching can expose individuals to predators, diseases, or

harsh environmental conditionsSometimes offspring such as special breed dogs can have

negative traits as a result of selective breeding (hip dysplasia etc)

Disadvantages: Sexual Reproduction cont’d

Fertilization can not take place during the gestation periods (when the female is already expecting).

In some instances this can result in an Endangered Species because animals are dying/being killed faster than they are being replaced through reproduction.

Asexual Reproduction One parent: organism produces

offspring without fertilizationUniform offspring :

Because offspring inherit all of their DNA from one parent, they are genetically identical to each other and to their parent

Cell Divison: Asexual Reproduction

Cell Division (Fissio)n: Cell division in prokaryotes that forms two genetically identical cells DNA is copiedCell becomes largerCell splits to form two new uniform, identical

offspring Examples: bacteria, Ecoli, pond critters

Budding: Asexual Reproduction

Budding: a new organism grows by mitosis and cell division on the body of its parentThe bud, or offspring is identical to the parentThe bud, when large enough, can break off of

the parent and live on its ownOffspring may remain attached and form a

colony Examples: Yeast, Hydra, cactus, some house

plants

Fragmentation/Splitting: When an organism divides into two halves

and each half becomes a new identical organism.

Example: Sea Stars and Flatworms

Vegetative Propagation (cuttings): Asexual

Vegetative Propagation: uniform offspring grow from a part of a parent plant- can cut off part also.

Runners- StrawberiesCuttings- Geraniums

Advantages: Asexual Reproduction

Enables organisms to reproduce without a mateNo wasted time and energy

Enables some organisms to rapidly reproduce a large number of uniform offspring

Disadvantages: Asexual Reproduction

Because their offspring are identical, there is no genetic variation that can give an organism a better chance for survivalExample: If a weed killer can kill the

parent, it will also kill the offspringA whole species can be wiped out from

a diseaseDangerous mutations in DNA – if the

parent has the mutation in their DNA, the offspring will have it too.

ExamplesExamples: Asexual Reproduction

MISSED ANYTHING??

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