A mini lecture on cell division. This slidecast supports the BC Science 9 curriculum and is tied to Open School's Science 9 Module 1.

1. Science Elluminate Session
Wednesday February 20th, 2008

2. Science 9 Agenda
Deadlines and Reminders
Review
Question Time

3. Science 9 - Deadlines & Reminders
This week: complete sections 1.3 and 1.4
Week of February 25th: write module test or hand
in project
Week of March 3rd: complete section 2.1
See the Grade 9 calendar for deadlines.
OUR GOAL -- BE DONE BY JUNE 6th!!!

4. Science 9 -- Cell Review
Cell Parts and Functions
Plant Cells vs. Animal Cells
Nucleus: procaryotic vs eukaryotic
DNA, Genes, and Chromosomes

5. Science 9 - Making Proteins
DNA --> mRNA --> protein
DNA: made of nucleotides, double stranded, in nucleus
mRNA: made of nucleotides, single stranded, in cytoplasm
protein: made of amino acids, made by ribosomes in cytoplasm
Use codon chart (pg 33) to determine what amino acid is coded
by the mRNA.
Bottom Line: DNA is the genetic code; it determines what we
are, who we are and what we are made of.

6. Science 9 - Cell Division
Cell Cycle:
Cells spend most of their time growing.
Before cells divide, all of the information in the DNA must be
copied; this process is called mitosis.
When the cell actually divides, this is called cytokinesis
(cyto = cell)

8. Science 9 - Phases of the Cell Cycle
Simple mnemonic: I Put My Alligator Through College
I = Interphase -- the longest part of the cell cycle, cell growth and
repair, organelles are duplicated
P = Prophase -- 1st stage of mitosis
nuclear envelope dissolves, chromosomes condense and become
visible, centrioles start moving to the poles, spindle fibres become
visible and attach to chromosomes
M = Metaphase -- 2nd stage of mitosis
X-shaped chromosomes line up along the centre of the cell
A = Anaphase -- 3rd stage of mitosis
chromosomes are pulled to opposite ends of the cell
T = Telophase -- 4th stage of mitosis
nuclear membrane forms around the two new nuclei, spindle
disappear, chromosomes unwind and are no longer visible.
C = Cytokinesis -- cell divides in half (animal cell pinches, plant cell,
cell plate forms)

9. Science 9 -- Meiosis
Mitosis is a form of asexual reproduction where there is a single
parent producing 2 identical offspring (cells).
Sexual Reproduction requires 2 parents and results in offspring
that are not identical.
Sexual Reproduction involves sperm and eggs (ova).
What would happen to the number of chromosomes if sperm
and eggs were produced by mitosis?
Meiosis is the form of cell division used to produce eggs and
sperm.

10. Science 9 - Question Time