Transcript Cell division - mitosis power point

Cell Division - Mitosis
So WHY do cells divide?
Smaller cells have a larger
surface area (cell membrane) to
volume (cytoplasm/organelles)
ratio and therefore are more
efficient in getting things in
(nutrients) and out (wastes) of
cells.
When do cells divide by mitosis?
a) during growth
b) for repair (regeneration)
c) reproduction in single cell organisms
During Growth
For Repair (Regeneration)
Reproduction- for single celled organisms
MITOSIS
Cell division in body/somatic
cells
One chromosome after
duplication/replication has 2
chromatids!
Sister
chromatids
made during
S phase of
Interphase
It goes
from B to
C during
Anaphase
Some vocab
 Chromosomes- long thread of DNA in nucleus
- there are 46 chromosomes in each cell
 Genes - small section of chromosome/DNA
 Chromatids- each duplicated strand of
chromosome.
 Centromere- structure that holds the
identical pairs of chromosomes (chromatids)
together.
Cell Cycle
•Cell cycle includes
interphase & mitosis
•Interphase is the longest
part of the cell cycle.
 Interphase
 G1 = first growth phase ~
9 hrs
 S = Synthesis phase ~ 10
hrs
 G2 = second growth
phase ~ 2 hrs
Cell cycle memory aid
 Interphase, Prophase, Metaphase, Anaphase, Telophase,
Cytokinesis
Intelligent People Meet At Three o’Clock
Intergalactic People Make A lot of Tiny Cars
Ian parties Mainly At Twelve o’Clock
Insane People Make A Terrific Casserole
Indecisive People Make A Terrifying Child
Interesting Peas Make (P)Terodactyl Clocks
Insects Poop Mega And Tough Cookies
Intelligent Prophets Make Amazing Turkey Casseroles
Interphase
• Parent Cell – “Resting Phase”
• Cell is undergoing normal cell activities (Protein Synthesis,
etc..)
• Not really ‘at rest’, but not actively dividing!
• The Chromosomes are in an extended form and seen as
chromatin (DNA+protein) - dense mass.
• The nucleus is visible.
• Cell size increases
• DNA of the chromosome is replicated.
Prophase
• Chromatin condense so that they are seen to consist of 2
chromatids joined by a centromere.
• The centrioles move toward opposite poles of the cell.
• Spindle fibers are produced & extend from each
centrosomes.
• Nuclear membrane starts to disappear
• Nucleolus is no longer visible
Metaphase
• The chromosomes line up at the equatorial plate.
• The spindle fibers from each centrioles are attached
to the centromeres of the chromosomes.
• The nuclear membrane has completely
disappeared.
Anaphase
•
•
The centromeres splits & the sister chromatids separate as each is pulled
to an opposite pole.
Single strand chromatid are now called chromosomes
Telophase
•
•
•
•
The chromosomes become longer, thinner, & less distinct
New nuclear membrane forms
The nucleolus reappears
Cytokinesis begins
Cytokinesis
 Cytoplasm divides
 Cleavage furrow- cytokinesis in animal cells
 Cell plate forms- cytokinesis in plant cells
 Two daughter cells are formed with their own
nucleus
CELL IN INTERPHASE….
Daughter Cells – “Resting Phase”
See the chromatin
IN SUMMARY
-Mitosis is:
Nuclear
Duplication
-Cytokinesis
Is Cytoplasmic
division
Mitosis & Chromosome Terms
(ploidy = number)
 Monoploid or haploid(n)- half the normal condition
in animals (ie. Sex cells)
 Diploid(2n)- normal chromosome condition
 Tetraploid(4n)- 2times normal condition
Humans: n=23 chromosome
therefore…
46 chromosome in our body cells &
23 chromosomes in our sex cells
If 23 = n; then 46 = 2n; and 92 = 4n
Chromosome
Interphase: The
DNA Replicates
&
chromosomes
are doubled
Chromosome
Chromatid
Chromosome
Anaphase: the
centromere splits
and the 2
chromatids are now
2 chromosomes
Chromosome
Condition:
Interphase: 2n
Prophase: 2n
Metaphase: 2n
Anaphase: 4n
Telophase: 4n
Whitefish Blastula
LAB B-1-3 Drawings:
INTERPHASE
METAPHASE
METAPHASE
PROPHASE
ANAPHASE
DAUGHTER CELLS
TELOPHASE
ANAPHASE
TELOPHASE
http://www.iknow.net/CDROMs/cell_cdrom/cellmovies.shtml
http://www.sci.sdsu.edu/multimedia/mitosis/mitosis_control.html
http://www.cellsalive.com/mitosis.htm
Mitosis Tutorial for Students
http://www.biology.arizona.edu/Cell_bio/tutorials/cell_cycle/cells3.html
http://hrsbstaff.ednet.ns.ca/bfougere/science9assist.htm