Cytology / Cell Biology
Cell Reproduction
Mitosis & Meiosis
Recalling the functions of the Plasma
Membrane…
(pre-lab discussion)
In your body, which organs perform the functions of
a cell membrane?
• Gas exchange  lungs
• Nutrients absorption  small intestine
• Waste excretion  kidneys / intestines
• Osmotic balance (water & salts)  kidneys
In your body, what determines the demand for
nutrients and oxygen and the production/supply
of wastes?
• Your size & the amount of metabolism happening
S.A./V Ratio and Cell Division
(cube lab)
BRRRRR!!!
Compare a cell to an animal:
Mouse: large surface area per volume,
loses heat quickly
Elephant: small surface area per volume,
loses heat slowly
Discuss with your partner and
summarize in your notes
how the SA/volume ratio limits
the size of a cell.
Make sure to refer to the cell
membrane and cytoplasm and
explain why.
There once was an egg… 
This kind of egg… 
Then came the barbarians…
or was it the Bears?
They came in huge numbers!
But in the end, there
could be only one!
Egg and sperm were happily united in the process
of fertilization… 
1 set of
chromosomes
from dad
(23)
1 set of
chromosomes
from mom
(23)
… and formed a zygote (2n = 46), the first cell of an
embryo.
A Sea Urchin Embryo in Cell Division
(looks a lot like you ~15 years ago)
Embryonic Development:
Cell Migration & Differentiation
Cell
migration in
Gastrula
3 Tissue layers:
(no memorizing)
1. Ectoderm  skin
(epidermis), hair, nails,
nervous system
2. Mesoderm  muscles,
bones, circulatory system
3. Endoderm  inner lining of
digestive tract & lungs,
glands
Blastopore
Mitosis & Meiosis in Life Cycle of Organism
First cell of new
organism is
diploid (2n),
2 sets of
chromosomes
Mitosis
Cells multiply &
differentiate into
various tissues
Zygote
Happy Birthday!
Fertilization
In sexual
reproduction,
male & female
gametes unite
(n + n = 2n)
Growth & Development
+
Meiosis
Gametes made: haploid (n), 1 set of chromosomes;
in humans, n = 23 chromosomes
Cell Reproduction Notes
Mitosis
What is it?
What type of cell
undergoes/uses it?
Where does it occur in
the organism?
What type of cell is
produced and what is it
genetic makeup?
Why is it important?
Cell (nuclear) division in
eukaryotic cells that produces
copies of a cell (bacteria
undergo binary fission, a
simpler process)
Meiosis
Cell (nuclear) division in
eukaryotic cells that produces
cells with half the number of
chromosomes of a cell
Cell Reproduction Notes
Mitosis
Meiosis
What is it?
Cell (nuclear) division in
eukaryotic cells that produces
copies of a cell (bacteria
undergo binary fission, a
simpler process)
Cell (nuclear) division in
eukaryotic cells that produces
cells with half the number of
chromosomes of a cell
What type of cell
undergoes/uses it?
All somatic (body) cells
Cells in gonads (sexual
glands)
Where does it occur in
the organism?
What type of cell is
produced and what is it
genetic makeup?
Why is it important?
Cell Reproduction Notes
Mitosis
Meiosis
What is it?
Cell (nuclear) division in
eukaryotic cells that produces
copies of a cell (bacteria
undergo binary fission, a
simpler process)
Cell (nuclear) division in
eukaryotic cells that produces
cells with half the number of
chromosomes of a cell
What type of cell
undergoes/uses it?
All somatic (body) cells
Cells in gonads (sexual
glands)
Where does it occur in
the organism?
All tissues
Testes in male, ovaries in
female
What type of cell is
produced and what is it
genetic makeup?
Why is it important?
Cell Reproduction Notes
Mitosis
Meiosis
What is it?
Cell (nuclear) division in
eukaryotic cells that produces
copies of a cell (bacteria
undergo binary fission, a
simpler process)
Cell (nuclear) division in
eukaryotic cells that produces
cells with half the number of
chromosomes of a cell
What type of cell
undergoes/uses it?
All somatic (body) cells
Cells in gonads (sexual
glands)
Where does it occur in
the organism?
All tissues
Testes in male, ovaries in
female
What type of cell is
produced and what is it
genetic makeup?
Daughter cells are identical to
each other and mother cell;
diploid
(2n, 2 sets of chromosomes)
Gametes/sex cells:
Spermatozoa/sperm in male,
ovum/egg in female; haploid
(n, 1 set chromosomes)
Why is it important?
Cell Reproduction Notes
Mitosis
Meiosis
What is it?
Cell (nuclear) division in
eukaryotic cells that produces
copies of a cell (bacteria
undergo binary fission, a
simpler process)
Cell (nuclear) division in
eukaryotic cells that produces
cells with half the number of
chromosomes of a cell
What type of cell
undergoes/uses it?
All somatic (body) cells
Cells in gonads (sexual
glands)
Where does it occur in
the organism?
All tissues
Testes in male, ovaries in
female
What type of cell is
produced and what is it
genetic makeup?
Daughter cells are identical to
each other and mother cell;
diploid
(2n, 2 sets of chromosomes)
Used in growth and repair of
tissues
Gametes/sex cells:
Spermatozoa/sperm in male,
ovum/egg in female; haploid
(n, 1 set chromosomes)
Halves the no. of
chromosomes from one
generation to the next; sexual
recombination  genetic
diversity in species
Why is it important?
Binary Fission - Prokaryotes
Period 8 Students:
Answer the questions below after completing the
first page of your notes:
1. If you get a skin wound, what type of cell division will be
used to replace the damaged cells?
2. Why is it important in this process for the daughter cells
to be genetically identical to the mother cell?
3. Are somatic cells haploid or diploid?
4. What type of cell division does NOT happen in your
body until puberty? How does this differ from the
process used to repair your skin?
5. Why is it important for gametes to be haploid (n)?
6. What is the advantage of sexual reproduction vs.
asexual reproduction for a species?
Cytokinesis = division
of cytoplasm (starts in
Telophase)
Cell Cycle
Mitosis =
nuclear division
(karyokinesis),
4 stages
Interphase:
G1 = Gap 1: Daughter cells grow
Cells may go into G0
indefintely (nondividing
phase); some cells
cease division, such as
nerve cells.
S = Synthesis: DNA is synthesized / replicated
G2 = Gap 2: Cell prepares for mitosis by making proteins,
ribosomes, mitochondria, etc.
Cell Cycle - Movie Time
(leave ppt)
In Interphase, DNA is the form of chromatin, not chromosomes
Interphase – “spaghetti
bowl” (chromatin),
DNA replication
Prophase/Metaphase –
double-stranded
chromosomes
As the cell prepares for mitosis, the DNA is coiled and packaged
into chromosomes;
chromosomes are double-stranded in Prophase because the DNA
was replicated in Interphase.
Prophase of Mitosis: Replicated (double-stranded)
chromosomes condense;
two chromatids are joined at the centromere.
The Phases of Mitosis / Karyokinesis
in the African globe lily
(Scadoxus katherinae)
Prophase
Metaphase
Anaphase
Mitosis /
Karyokinesis
Telophase
(cytokinesis
starts here)
2 daughter
cells
(cytokinesis
finished)
Can you identify the phases of mitosis?
Cytokinesis is
starting
Late
Anaphase
or
Telophase?
2. Metaphase
(chromosomes
align at equator)
3. Anaphase
(centromeres break,
chromosomes pulled to
opposite poles)
1. Prophase (early)
(DNA condensing /
chromosomes
forming)
Animal Cells in Several Stages of Mitosis
4. Telophase (last phase of
mitosis - citokinesis starts)
Animal Cells in Cytokinesis
(cytoplasm/membrane division)
after Mitosis
Cleavage furrow
Onion Root Cells in Several Stages of Mitosis
Interphase
1. Prophase
(DNA condensing, nuclear
envelope disintegrating)
(chromatin,
nucleolus)
3. Anaphase
(chromosomes
pulled to
opposite poles)
2. Metaphase
(chromosomes
align at equator)
4. Telophase
(cytokinesis starting,
nuclear envelopes (2)
form)
MOVEMENT OF CHROMOSOMES DURING CELL DIVISION
* ADD THIS DIAGRAM TO YOUR NOTES *
Pole-to-pole fiber,
elongates cell for
division
Centromere-to-pole fiber,
moves chromosome to and
from metaphase plate
Protein disk that attaches to
kinetochore fibers at centromere
Summarize & Illustrate
(after mitosis lab & w.s.)
• Complete your mitosis notes
diagrams using n = 2, 2n = 4
• Use different colors for
mom’s and dad’s
chromosomes (2 from each
parent, one big, one small)
• Label the chromatids,
centromere, and kinetochore
on one chromosome
(prophase)
• Annotate/briefly explain what
happens in each phase of
mitosis on your diagram
Mitosis Worksheet
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