Download meiosis mitosis cell cycle

Cell Reproduction
1
The Cell
Cycle
2
start
Division of
everything
else
P, M, A, T
Division of nucleus
3
The Cell Cycle
Fig. 8.4, p. 130
Cell Cycle
• Cycle starts when a new cell forms
• Has 3 stages of CELL CYCLE
– Interphase G1, S, G2
– Mitosis phase (dividing of nucleus) thru
p,m,a,t
– Cytokinesis division of everything else from
cell
3 easy steps to divide a bacteria
…(prokaryotic cells).. BINARY
FISSION:
• 1. chromosomes make copies
• 2. cell grows til about 2x its size!
• 3. cell membrane forms in
between the copied
chromosomes and the cell
SPLiTS!
Cell Division in Prokaryotes
Parent
cell
Chromosome
replicates
Cell splits
2 identical daughter cells
7
1)
2)
3)
If a fishes sperm cell has 12 chromosomes, how many
chromosomes does his scale cells have? _____
Your chromosomes look like a ______ and bacteria’s chromosome
looks like a _____.
Heredity information for most traits is generally located in
a.
b.
c.
d.
4)
Chromosomes found on genes
The ribosome of sperm cells
The mitochondria in the cytoplasm
Genes found on chromosomes
Compared to the number of chromosomes in a normal autosomal
(body) cell, the number of chromosomes in a sperm (sex) cell is
a.
b.
The same
Twice as great
c. four times greater
d.half
5) Which process is trying to stop global warming?
a. deforestation
b. combustion
c. photosynthesis
d. industrialization
B. Mitosis
Mitotic Phase (Nucleus Divides)
2nd phase of cell cycle …remember
• Four stages:
Prophase
Metaphase
Anaphase
Telophase
Early Prophase
(interphase)
spindle starts forming
Chromatin starts to coil
Chromosomes
10
Prophase
 Nuclear membrane
breaks down
 chromatin coils into
duplicated
chromosomes (X’s)
 Kinetochores form
 Spindle fibers form
 Centrioles start
moving to opposite
sides
Metaphase
Spindle fibers attach to the kinetochores
and the Chromosomes move to the
MIDDLE, line up single file (center,
equator of the cell) (a line of 46
chromosomes long)
Equator of Cell
Pole of
the Cell
12
Anaphase (break apart)
• Chromatids (half of
an X) are pulled
apart (separate)
– Now each side has
the same copy of
DNA
• Cell elongates
Telophase
• Chromatids uncoil to chromatin
• Spindle fibers go away
• Nuclear membranes start to form
• Cell continues to get bigger
Starts to look like Two cells
(Opposite of Prophase)
Cytokinesis
Division of the cell into 2
In plant cells, cell plate forms at
the equator to divide cell
In animal cells, cleavage furrow
forms to split cell
16
2) Animal Cell Division
Results of Mitosis
• 2 cells with identical
DNA (diploid #)
• Chromosomes in
unduplicated form
• Cell CYCLE
STARTS OVER
AGAIN…G1
Name
the
Mitotic
Stages:
Interphase
Name this?
Prophase
Telophase
Name this?
Metaphase
Anaphase
19
1) What are the 3 phases of the cell cycle?
2) What can interphase be broken down
into?
3) What happens during the S phase?
4) What does mitosis mean? What cells do
this process?
5) What does cytokinesis mean?
6) How many cells will there be by the end
of the cell cycle if we started with 1 cell?
7) Who does binary fission?
LETS TALK ABOUT
SEX!!!!!!
CELLS…..Got ur attention
now huh????
Meiosis
only in sex cells (haploid)
• Occurs here is men = testes that produces
sperm
• And here in women = ovaries that
produces eggs
– EGG & SPERM cells have half the # of
chromosomes!....they have 23 chromosomes
each (n)…when they come together…(2n)
Meiosis: One Replication and
Two Divisions(PMAT 1 and
PMAT 2…ex:P1, A2)
Mitosis: One Replication and One
Division* (just PMAT)
• Meiosis: 4 haploid nuclei form (because 2 divisions)
• Mitosis: 2 diploid nuclei form (because 1 division)
Early Prophase
(interphase)
spindle starts forming
Chromatin starts to coil
Chromosomes
25
Prophase I
Homologs pair up
called synapsis (mom
chrom #1 pairs with
dad chrom #1
Crossing over
occurs
Chromatin coils to
chromosomes (x’s).
Spindle forms.
Nuclear membrane breaks.
Centrioles move to
opposite poles
26
Homologous Chromosomes Carry
same Genes..different alleles (form
of a gene)
• Cell has two of each chromosome, One
chromosome in each pair from mother,
other from father
brown
blue
Mom’s
Dad’s
Crossing-Over
 Homologs cross over and
genes are
exchanged……produces
genetic diversity (makes
each cell genetically
different)
28
Metaphase I
• Homologs meet in
the Middle, lining up
in their PAIRS
(double file, 23 long)
• Random assortment
of chromosomes
…..not all of
mommies on one
side…
Anaphase I
• *Homolog pairs*
break apart
• Go back as a whole
duplicated
chromosome (X’s)
Telophase I
• Nuclear membranes
reform
• Spindle fibers go away
• Cell elongates
• Cytokinesis spilt of
cytoplasm to form 2 cells
each with haploid # (23),
but chromosomes are still
duplicated
• Chromosomes do not
uncoil
ANSWER
1) When does crossing over occur?
2) When does the nuclear membrane disappear?
3) When does chromatids separate (break apart)?
4) When do chromosomes meet in the center?
5) How many cells end mitosis? Meiosis (2 divisions)?
T/F
1) Human sperm have 23 chromosomes
2) Cell division in bacteria(prokaryote) is binary fission
3) Mitosis is the process by which the nucleus divides
4) After interphase comes cytokinesis
5) DNA is replicated in the G1 phase
6) Chromatin coils up during anaphase
Meiosis II: Reducing
Chromosome Number
Prophase
II
Metaphase
Telophase
II
Anaphase
4 Genetically
II
II
Different
haploid cells
33
Prophase II
• Centrioles move to
opposite poles
• Nuclear membrane
goes away
• Spindle fibers form
Metaphase II
• 23 Duplicated
chromosomes meet
in the middle (single
file)
Anaphase II
• chromatids
separate (break
apart)
Telophase II
•
•
•
•
Spindle fibers disappear
Chromosomes uncoil to chromatin
Nuclear membrane forms
Cytokinesis occurs producing Four
HAPLOID cells…THAT ARE ALL
GENETICALLY DIFFERENT
Comparison of Divisions
Mitosis
Meiosis
2
Number of
divisions
1
Number of
daughter cells
2
4
Genetically
identical?
Yes
No
Chromosome #
46
23
Where
body cells
Sex cells
When
Throughout life
At sexual maturity
Growth and
repair
Sexual reproduction
Role
38
Gametogenesis
Oogenesis
or
Spermatogenesis
39
Oogenesis making of
eggs through meiosis
Occurs in the ovaries
produce 3 polar bodies that die
(smaller) and 1 oocyte (immature egg
that is bigger) will turn into an egg
(ovum)
Starting at puberty, one oocyte
matures into an ovum (egg) every 28
days
Find the: ovum & polar bodies
Spermatogenesis= making
sperm
Occurs in the testes
produce 4 spermatids
(baby sperm without
tails)
Spermatids mature into
sperm…grow tail
Men produce about 250
million sperm per
day…..only 1 will win
42
spermatogonium
(diploid )
primary
spermatocyte
(diploid)
secondary
spermatocytes
(haploid)
spermatids
(haploid)
sperm (mature,
haploid male
gametes)
Spermatogenesis
Growth
Meiosis I,
Cytoplasmic Division
Meiosis II,
Cytoplasmic Division
cell differentiation,
sperm formation
Spermatogenesis – making sperm cells
Fertilization
• When sperm and egg fuse (23 +23= human 46)
• 2 gametes coming together is random 
– Adds to variation among offspring
– Remember all eggs and sperm are different from each
other, this is why u don’t look exactly like your siblings.
TWINS
• Fraternal Twins look different
– 2 eggs and 2 sperm……remember… all sperm and eggs are
different so of course they wont look alike..can be diff sex
• Identical Twins  look the same
– One egg and one sperm…..once fused, embryo splits….so same
DNA b/c same sperm and egg…….always same sex
– Conjoined twins…. starts to split….but does not finish
Question
If a pair of identical boy twins hooked up
with a pair of identical girl twins on the same
day, then they each had a child on the same
day, would the babies be genetically the
same (identical)? Why or why not?
Things to Know:
1)
2)
3)
4)
5)
6)
7)
8)
9)
All things on MP3 review for chapter 8
Cell Cycle  G1 S G2
What are spindle fibers for
Sexual vs asexual reproduction
How twins happen….fraternal vs. identical
What does the cleavage furrow do…..splits the cell into 2
Where mitosis and meiosis occurs and there phases
Chromosome #’s
Prokaryotic chromosomes and their division