Transcript all cell division starts with interphase

ALL CELL
DIVISION
STARTS WITH
INTERPHASE
INTERPHASE
is part of the cell cycle that occurs
between divisions.
-During this phase the cell is producing
materials necessary for cell division.
-3 Phases
G1- growth and development
S - (Synthesis) chromosomes
replicate (copy)
G2- synthesis of organelles for cell
division
EX. centrioles.
What is Happening with the
DNA?
1. DNA is generally found in the
CHROMATIN form which is thin and fibrous
during interphase.
2. Chromatin condenses to form sister
chromatids which are identical structures
of replicated chromosomes joined at the
centromere.
centromere - point where sister chromatids
are joined together. This point varies
depending on the chromosome.
SISTER
CHROMATID
Chromosome 1 is an exact
copy of Chromosome 2
Chromosome 1
Chromosome 2
MITOSIS-Process during which
the cell nucleus divides into 2
identical nuclei
-4 Stages
I - Prophase
II - Metaphase
III - Anaphase
IV - Telophase
1. Prophase
A. Chromosomes in the nucleus condense to
form sister chromatids. Centrioles move
to opposite sides of the cell.
B. Spindle Fibers (small tubules made up of
proteins) start to form from each centriole.
C. Nuclear Membrane breaks into fragments.
Spindle Fibers attach to the centromeres.
D. Nuclear Membrane disappears. Spindle
fibers begin to move the sister chromatids
towards the center of the cell.
2. Metaphase
Spindle fibers pull sister chromatids to line
up in the center of the cell. This imaginary
line is called the metaphase plate. If this
does not happen correctly, genetic
material will not be evenly distributed.
3. Anaphase
A. Centromeres break up.
B. Spindle fibers pull 1 set of
chromatids (1 sister- 1 set of
chromosomes) towards 1 pole and 1
set towards the other pole.
4. Telophase – Reverse of Prophase
A. Nuclear Membranes begin to form.
B. Spindle fibers disassemble.
C. Chromosomes uncoil to form
chromatin.
D. 2 complete nuclear membranes are
finished.
10
Name each stage as you see it occur?
Mitosis Animation
Cytokenesis -cell division
(cytoplasm divides)
In animal cells- cell membrane pinches
off.
In plant cells – pieces of membrane form
at the metaphase plate & grow together
to forma new cell membrane. A cell wall
forms between the membranes.
Mitosis occurs in ALL of our cells. ALL
of our cells have copies of ALL of our
DNA.
Each cell produced by mitosis is diploid.
12
Cleavage
Cell plate in
Cytokinesis
furrow in animal plant cell
cell
It’s all about the number of Chromosomes.
Diploid – Contains 2 complete sets of
chromosomes (2n). In humans 1 set from
mom, 1set from dad so a total of 46
chromosome Ex. Chromosomes containing
genes for blond AND black hair color.
(Don’t forget chromosomes double right
before cell division so you are looking at 92
chromosomes at the start of mitosis and
meiosis for humans)
Mitosis produces new somatic (body cells)
and Asexual reproduction.
Cut out and put in order labeling which phase
Name the Stages of Mitosis:
15
Early Anaphase
Early prophase
Metaphase
Interphase
Late
Prophase
Late telophase,
Mid-Prophase
Advanced
cytokinesis
Early
Telophase,
Begin
cytokinesis
Late
Anaphase
16
?
Identify the Stages
Early, Middle, & Late Prophase
?
?
Metaphase
Late Prophase
Anaphase
?
?
Late Anaphase
?
Telophase
?
Telophase &
Cytokinesis
Meiosis
occurs to produce gametes in
SEXUAL reproduction.
Gametes – sex cells, haploid reproductive
cells. In humans the sperm and the egg.
Haploid – Contains only 1 set of chromosomes
(1n).
In humans only gametes contain a total of 23
chromosomes. Ex. Chromosomes containing
genes are for either blond OR black.
Meiosis –cell reproduction by division which
reduces the number of chromosomes in half- In
humans 4623.
(pg 276-277)
1 cell divides to form 4 cells with half the
number of chromosomes. (Don’t forget
chromosomes double right before cell division
so you are looking at 92 chromosomes at the
start of meiosis for humans)
Why do I want ½ number of
chromosomes in sex cells?
from mom
from dad
child
too
much!
meiosis reduces
genetic content
The right
number!
Education.com
21
How Homologous chromosomes Lining Up in
Metaphase 1 is 1 Key to Variation.
Gene X
Hair color
Homologous
same genes,
different alleles
(choice Of genes blond
hair/black
Hair)
Sister
Chromatids
(same genes,
same alleles)
Homologs separate in meiosis I and therefore
different alleles separate.
Crossing-Over
22
1. Homologous
chromosomes in a
tetrad cross over
each other
2. Pieces of
chromosomes or
genes are
exchanged
3.Produces
Genetic
recombination in
the offspring
23
Meiosis Animation
Fertilization- Gametes fuse to form a zygotethe first cell of a new organism.
Zygote- 1st cell after fertilization.