Science meiosis in grade 11 stemmmmmmmmm

science

1. MEIOSI
S

2. Why don’t you look and act
EXACTLY
like either one of your
biological
parents or siblings?

3. •Sexual= egg and sperm
•Most animals
•Asexual=produces offspring
that are identical to the
parent•Binary Fission- bacteria
•Fragmentation-
•Budding- yeast, anemones
SEXUAL VS. ASEXUAL
REPRODUCTION

4. •Leads to a species
•Produces haploid cells used in
reproduction
•Creates
•IMPORTANT TO THE SURVIVAL OF THE
SPECIES
PURPOSE OF
MEIOSIS

5. •WITHOUT MEIOSIS CHROMOSOMES
WOULD MULTIPLY EXPONENTIALLY
•In humans-
•46 + 46 =
•92 + 92 =…
•184 + 184 =…

6. •Produces sex cells
•Also called germ cells
•Also called gametes
•Male gamete = sperm =
spermatogenesis
•Female gamete = egg= oogenesis

•That are haploid (n)
MEIOSIS
PRODUCES…

7. •Body (Somatic) Cells are diploid (2n)=
this is the full number of chromosomes

•Eggs and sperm are each haploid (n)=
have ½ the number of chromosomes of
the body cells.
•They contain the genes passed on to
the offspring.
PLOID
Y

8. •When the sperm (n) enters the egg (n)
=fertilization

•The fertilized cell is then called a
zygote
•Has diploid # (2n) of chromosomes
•Mitosis ensues

9. •Fruit fly
•Pea
•Corn
•Tomato
•Frog
•Apple
•Chimpanzee
•Dog
•Fern
•Human
8
14
20
24
26
34
48
78
1260
46
4
7
10
12
13
17
24
39
630
23
•Organism Body Cell (2n)Gamete (n)

11. •Two separate divisions
•Produces four haploid (n) cells
•Begins with one diploid (2·n)
cell
•Meiosis
I
•Meiosis
II
MEIOSI
S

12. BEFORE
MEIOSIS:
•INTERPHASE is when DNA is
replicated

•Why does it duplicate?

13. •Homologous chromosomes (the original
from each parent and its replication)
pair with each other = called a tetrad

•Crossing over
MEIOSIS 1: PROPHASE
1
•Occurs anywhere on chromosomes
•Exchange of genetic material =traits in
Prophase I
•AKA genetic recombination

14. CROSSING
OVER

15. •The tetrad lines up in the middle
•(In mitosis, each chromosome lines up
in the middle)
MEIOSIS 1: METAPHASE
1

16. •Chromatids DO NOT separate
•Each homologous chromosome (with 2
chromatids) goes to opposite poles
(centrioles) along the spindle fibers.
•This is called Mendel’s Law of
Independent Assortment

•(In mitosis the chromatids DO separate
and go to opposite poles)
MEIOSIS 1: ANAPHASE
1

17. •2 new nuclei are formed
MEIOSIS 1: TELOPHASE
1

18. •The parent cell has divided into two
new haploid cells

•Each cell has one of the homologous
chromosomes.
•(In mitosis each new cell has one of
each identical chromosome)
MEIOSIS 1:
CYTOKINESIS

19. MEIOSIS II: PROPHASE
II•The DNA does not replicate
•The cells are haploid (n)

20. •Chromosomes line up at the
equator
MEIOSIS II: METAPHASE
II

21. •Chromosomes split
•One of each pair pulled to opposite
poles
MEIOSIS II: ANAPHASE
II

22. •Two new nuclei are formed from the 2
new daughter cells in MEIOSIS I
MEIOSIS II: TELOPHASE
II

23. •Cells divide
•Final result= 4 new haploid (n)
cells
MEIOSIS I:
CYTOKINESIS

26. •http://www.youtube.com/watch?
v=ijLc52LmFQg
KHAN ACADEMY
DEMO