7th Life Science Betsy Sanford Lost Mountain Middle School Mitosis vs. Meiosis 7th Life Science Betsy Sanford Lost Mountain Middle School

The Cell Cycle asexual reproduction all types of organisms can do mitosis all cells except the sex cells most human body cells go through the cell cycle with mitosis mitosis is used to… grow new cells replace old cells repair damaged cells

Asexual Reproduction the cell cycle using mitosis starts with 1 cell new cells have a copy of the DNA DNA is the same in all cells (exact copy) ends with 2 cells in humans, 46 chromosomes in each new cell

The Cell Cycle Interphase – copying DNA Mitosis forming 2 new cells each cell has a nucleus and a full set of DNA PMAT (Prophase, Metaphase, Anaphase, Telophase) Cytokinesis – the 2 cells split apart

Asexual Reproduction the use of mitosis to create a new organism examples… mushrooms make spores that grow new mushrooms sea stars grow whole new bodies by regeneration bacteria undergo binary fission plants and fungi create buds that are fully formed new organisms that separate from the original

Asexual Reproduction Benefits individual organisms can create new organisms no mate needed rapid population no long term gestation

Asexual Reproduction Disadvantages DNA exactly the same, not diverse susceptible to diseases and disorders lack of adaptation ability for species

The Other Cell Cycle sexual reproduction all types of organisms can do meiosis as well sex cells ONLY sex cells are called gametes female cells are called egg cells male cells are called sperm cells meiosis is used to… create a new unique organism

Sexual Reproduction the cell cycle using meiosis to create sex cells starts with 1 cell (46 chromosomes in humans) DNA copied in Interphase 2 new cells created and then split again into 4 new cells ends with 4 cells with only ½ the DNA in each cell in humans, 23 chromosomes in each new cell (23 in each egg cell and 23 in each sperm cell)

Sexual Reproduction the use of meiosis to create sex cells (gametes) a sperm fertilizes an egg to create a zygote in plants, pollen is sperm and eggs are contained in flowers or cones (the zygote is called a seed) in bacteria, conjugation is the exchange of DNA by two cells

Sexual Reproduction in fish, females release eggs into the water and males release sperm into the water, fertilization is external (gametes mix in the water) mating (internal fertilization) happens with birds, amphibians, reptiles, mammals, and humans invertebrates (animals without external skeletons like insects) may either mate or fertilize externally

Sexual Reproduction Benefits genetic diversity, each offspring is unique when a sperm fertilizes an egg, ½ the chromosomes are from the male parent and ½ the chromosomes are from the female parent may have better survival characteristics such as disease resistance

Sexual Reproduction Disadvantages must have a mate the zygote (fertilized egg) often takes a long time to develop (gestation) examples… human females are pregnant for 40 weeks elephants are pregnant for almost 2 years