1. 7th Life Science Betsy Sanford Lost Mountain Middle School
Mitosis vs. Meiosis
7th Life Science
Betsy Sanford
Lost Mountain Middle School

2. 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

3. 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

4. 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

6. 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

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

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

9. 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

10. 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)

12. 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

13. 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

14. 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

15. 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