Sexual and Asexual Reproduction Methods of Reproduction Sexual and Asexual Reproduction

Reflection 4/25 – Name and define the 2 types of reproduction 4/26 – Name advantages and disadvantages of asexual reproduction.

What is sexual reproduction? Requiring 2 parents male and female (egg & sperm) The egg and sperm join (zygote) to form an entirely new organism Offspring are different from the parent organism because

Sexual Reproduction: Requiring 2 parents (egg & sperm) Combining different genetic material

Methods of sexual reproduction: Pollination External Fertilization Internal Fertilization

Sexual Reproduction A type of reproduction in which the genetic materials from two different cells combine, producing an offspring The cells that combine are called gametes Female – egg Male – sperm Fertilization: an egg cell and a sperm cell join together A new cell is formed and is called a zygote

Sexual Reproduction Requires two parents that each share ½ of the genetic information. Offspring share the characteristics of each parent. Meiosis 7

Sexual Reproduction All the members of the Animal Kingdom Fish Mammals Amphibians Birds Reptiles Insects Crustaceans 8

Sexual Reproduction Plant Kingdom Flowers are the reproductive organs of plants. Some flowers have both male and female reproductive organs on the same flower. Male flower Female flower 9

Sexual Reproduction Examples of organisms that reproduce sexually Chickens Iguanas Lobsters Sharks Humans Butterflies Sunflowers Roses 10

Sexual Reproduction Happens 2 ways Internally (inside) The egg is fertilized by sperm inside the female Mammals, birds, reptiles, insects, spiders Externally (outside) The egg is fertilized by sperm outside the female The female lays the eggs and then the male fertilizes them. Fish and some amphibians Plants and fungi (pollen and spores) 11

Sexual Reproduction in Flowering Plants Pollen is produced in the male organs of the flowers - anthers. Pollination occurs when pollen is transferred from the anthers to the female organs by wind or by animals. If the female stigma is receptive to a pollen grain, the pollen produces a pollen tube, which grows through the female tissue to the egg, where fertilization takes place by the sperm nucleus. Sexual Reproduction in Flowering Plants

Advantages: Sexual Reproduction Diverse offspring: genetic variation among offspring Half of the DNA comes from mom Half of the DNA comes from dad Due to genetic variation, individuals within a population have slight differences Plants – resist diseases Traits can develop to resist harsh environments that allows an organism survive

Disadvantages: Sexual Reproduction Time and Energy Organisms have to grow and develop until they are old enough to produce sex cells Search and find a mate Searching can expose individuals to predators, diseases, or harsh environmental conditions Fertilization cannot take place during pregnancy, which can last as long as 2 years for some mammals.

Examples: Sexual Reproduction

Asexual Reproduction: requires only 1 parent and the offspring are an exact copy of the parent---a clone

Methods of asexual reproduction: Binary fission Budding Fragmentation Parthenogenesis Vegitative Propagation Spores

Asexual Reproduction Requires only one parent Offspring have 100% the same chromosomes as the parent. In other words, the offspring are exact “clones” of the parent. Most unicellular organisms reproduce this way. Mitosis 18

Asexual Reproduction Examples of organisms that reproduce asexually Hydra Sea Star Strawberry Archaebacteria Eubacteria Euglena Paramecium Yeast 19

Asexual Reproduction: Organisms that reproduce asexually cannot develop much variety, because they are “copying” the original organism exactly.

Asexual Reproduction One parent: organism produces offspring without fertilization Uniform offspring: Because offspring inherit all of their DNA from one parent, they are genetically identical to each other and to their parent

Binary fission Single-celled organisms (Amoeba, paramecium, euglena) which use asexual reproduction can do so simply by dividing into two equal halves. This is called binary fission.

Fission: Asexual Reproduction Fission: Cell division in prokaryotes that forms two genetically identical cells DNA is copied The cell begins to grow longer, pulling the two copies apart The cell membrane pinches inward in the middle of the cell Cell 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 parent The bud, or offspring is identical to the parent The bud, when large enough, can break off of the parent and live on its own Offspring may remain attached and form a colony Examples: Yeast, Hydra, cactus

Budding In yeasts the cell does not divide equally in two halves; instead, there is a large mother cell and a smaller daughter cell. Yeast - budding

Budding- an offspring grows out of the body of the parent. Hydra Budding offspring Cactus Budding

Fragmentation- plant cuttings Some plants can grow from cutting them up and replanting them.

Fragmentation In this form, the body of the parent breaks into distinct pieces, each of which can produce an offspring. Pieces of coral broken off in storms can grow into new colonies. A new starfish can grow from one detached arm.

FRAGMENTATION: Asexual Reproduction Fragementation: occurs when an offspring grows from a piece of its parent. Producing new organisms: Sea Stars Sea urchins, sea cucumber, sponges, and planarians

Vegetative Propagation: Asexual Vegetative Propagation: uniform offspring grow from a part of a parent plant Parent plants sends out runners Where the runner touches the ground, roots can grow A new plant is produced even if the runner is broken apart Each new plant is uniform and identical to the parent. Examples: strawberries, potatoes, ivy, crabgrass

Parthenogenesis Parthenogenesis is a form of asexual reproduction in which females produce eggs that develop without fertilization. Parthenogenesis is seen to occur naturally in some invertebrates, along with several fish, amphibians, and reptiles as well as in many plants. There are no known cases of parthenogenesis in mammals.

Advantages: Asexual Reproduction Enables organisms to reproduce without a mate No 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 survival Example: If a weed killer can kill the parent, it will also kill the offspring A whole species can be wiped out from a disease Dangerous mutations in DNA – if the parent has the mutation in their DNA, the offspring will have it too.

Examples: Asexual Reproduction

Activity: How the uniform offspring of your creature Create a creature that reproduces asexually. Draw the creature Describe how the creature reproduces asexually Describe 1 advantage of reproducing this way Describe 1 disadvantage of reproducing this way Name your creature How the uniform offspring of your creature

Sexual vs. Asexual Reproduction Asexual reproduction results in offspring that are genetically identical to the parent organism. Sexual reproduction results in offspring that are genetically different from the parent organisms.

Asexual vs. Sexual Reproduction 37 37

Compare and Contrast What kind of map do we need to make? Types of reproduction in living organisms Pass DNA from parent to offspring Asexual Reproduction Sexual Reproduction 38

Summarize Write two paragraphs with 6 sentences each describing asexual and sexual reproduction. Paragraph 1: Asexual reproduction is….. Paragraph 2: Sexual reproduction is… 39