7th Science Cells and Heredity U2L3 – Sexual and Asexual Reproduction

Types of Reproduction: Asexual Reproduction * new organisms from one parent * DNA of offspring is identical to DNA of parent. Sexual Reproduction * sex cells from two parents combine * DNA of offspring is different from either

Examples of Asexual Reproduction Vegetative Reproduction * grow off of parent plant or sprout to form new plant *runner – above ground stem (strawberry) *tubers – underground stem (potato) *plantlets – tiny plants that grow along edges of plant leaves Strawberry runners - https://www.youtube.com/watch?v=LbMr6d-ACYw Vegetative reproduction of a potato – you can try this at home! - https://www.youtube.com/watch?v=jOCKZWthVng

*Division of parent organism into 2 parts Binary Fission *Division of parent organism into 2 parts * ex. Bacteria, Paramecium (Protist) *Type of reproduction of prokaryotes Binary fission - https://www.youtube.com/watch?v=dZzFTHKfZSg

* small, exact copy of adult grows from body of parent Budding * small, exact copy of adult grows from body of parent * ex. Hydra, yeast Budding yeast - https://www.youtube.com/watch?v=iOvrq6ssy2Y Buding hydra - https://www.youtube.com/watch?v=a5oHMjGqjyo OPTIONAL – SciShow – Hydras: Our Immortal, Tentacled Friends - https://www.youtube.com/watch?v=4h-tUWjesyg

* whole new organism grows from each piece of parent Regeneration * whole new organism grows from each piece of parent * ex. Sponge, sea stars, planaria (flatworm) * regrowing damaged or lost body parts Sea Star regenerating - https://www.youtube.com/watch?v=d5dOSyaKWTQ

* specialized cell that can survive harsh conditions Spore * specialized cell that can survive harsh conditions * light; carried by wind * ex: fungus, fern Exploding puffball - https://www.youtube.com/watch?v=VWgm322uKWI

Sexual Reproduction Two sex cells (egg and sperm) come together – process called fertilization. Sperm – formed in male reproductive organs Egg – formed in female reproductive organs -- much larger & contains food material New cell formed by fertilization is called a zygote Read and do pg. 116

Advantages of asexual reproduction Organism can reproduce quickly Offspring are identical to parent, to any favorable traits are passed on Parent does not need to find a partner All offspring can make more offspring (not just females)

Advantages of sexual reproduction Increases genetic variation Offspring have different traits than their parents Especially important if the environment changes Advantages of using both! SciShow “Why Sex?” – STOP AT 4:25 Answer the question – “Why do MOST organisms use sexual reproduction and not asexual?” Read page 119

Write this question in your notebook: “Why do MOST organisms use sexual reproduction and not asexual reproduction?”