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What to do…
Answer the following question on a half sheet of paper.
Put your name on the paper.
Be ready to discuss your answer.
In the diagram shown, the small
circles represent water molecules
moving through a membrane.
When will the water molecules
move INTO the cell?
A. When the concentration of water is higher inside the cell than outside the cell
B. When the concentration of water is lower inside the cell than outside the cell
C. When the concentration of water is the same inside and outside of the cell
Cell Division and
Mitosis
Standard: 1.4-Sequence a series of diagrams
that depict chromosome movement during plant
cell division
The Amoeba Sisters!
Cell growth & division
Why do cells divide? They get too large and lose
their ability to get all the necessary materials they
need.
It involves: The division of the nucleus is followed by
division of the cytoplasm (Cytokinesis)
Types of cell division:
1. Mitosis (body cells – somatic)
2. Meiosis (sex cells – gametes)
3. Binary Fission (bacteria)
Background Information: Following DNA replication,
chromosomes become visible. Each Chromosome
appears double in structure, held together by a single
structure:
Chromatid
Centromere
Double chain (DNA)
1 chromosome
(double stranded
structure)
Homologous Chromosomes: Most chromosomes appear
in homologous pairs.
1 chromosome
1 chromosome
1 pair Homologous Chromosomes
(different DNA)
ALIKE because:
1
2.
3.
Same size
Same shape
Same centromere
location
DIFFERENT because:
1.
One member of pair
from mom & the other
from dad.
Homologous Chromosome Examples:
Homologous Chromosome Examples:
Locus E/e = # of
fingers
6 fingers
Dominant
5 Fingers
Recessive
Homologous
A cell containing homologous
chromosomes is called Diploid (2N).
A cell containing 1 member only of each
homologous pair is called Haploid (N).
Each different species has a constant
number of homologous chromosome pairs.
Ex. Human = 23 pairs
Fruit fly = 4 pairs
Cell Cycle:
The repeating
phases in the
life of a cell
Interphase has 3 phases. Interphase is a period of growth
prior to Mitosis. And is the longest phase in cell cycle.
1. G1 Phase : Cell is growing
2. S Phase: DNA
(Chromosomes) replication.
3. G2 Phase: Preparing for
Mitosis
Mitosis:
Nuclear division = 4 phases
1). Prophase
2). Metaphase
3). Anaphase
4). Telophase
Defined:
a. Cell division in which the major event is
nuclear division followed by cytokinesis.
b. Occurs in somatic (body) cells only –
repair injured cells, growth, replace worn out cells.
The Cell cycle:
1. Interphase (Cell just prior to cell division)
**Not a phase in Mitosis**
Nuclear Membrane
Centrioles
a) Cell is growing – G1
b) DNA replication - S
Nucleolus
(double the DNA)
Chromatin c) Cell is preparing
for Mitosis – G2
Nucleus
2N - Diploid Cell
1. Prophase: 1st phase of Mitosis
Spindle Fibers
Sister
Chromatids
Nuclear
membrane
2N - Diploid Cell
a. Nuclear membrane
disappears
Nucleolus disappears
b.Sister chromatids
have condensed and
are visible
c. Spindle fibers are
formed.
2. Metaphase
Spindle Fibers
a.Sister Chromatids
are lined up at the
middle of the cell.
(equator)
2N - Diploid Cell
3. Anaphase
Single
Chromatid
2N - Diploid Cell
a.Centromeres split
so that each
chromatid has its
own.
a.Sister Chromatids
have been pulled
apart and are
moving to
opposite ends of
the cell.
4. Telophase:
a.2 new nuclei form in the
opposite ends of the cell
Nucleolus
2N
2N
b. Nuclear membrane
/Nucleolus reappear
c. Chromosomes uncoil &
become chromatin again.
Clevage
Furrow
Nuclear
membrane
2 new daughter cells
d. Cytoplasm pinches in
two (begin Cytokinesis)
Remember
PMAT
P
= prophase
M
= metaphase
A
= anaphase
T
= telophase
Cytokinesis
____Animal Cell
In animal cells - the cell
membrane pinches to
form a Clevage furrow
______
Plant Cell______
In plant cells – a cell plate
forms from the inside to
divide the cell in half.
Comparison: Mitosis
Plants
Animals
1. No Centrioles
1. Centrioles present
2. Cell plate forms,
no pinching apart
2. Cytoplasm pinches
in two
Results of Mitosis:
2 identical daughter cells with same
amount & kind of DNA as original cell.
Mitosis Recap!
Put it together. . .
• Complete the following skill sheet
utilizing your notes