Transcript Cell Growth and Division - Edmonds School District / Overview

CELL GROWTH AND DIVISION
Divide and Conquer
WHY AREN’T CELLS HUMONGOUS?
Exchanging Materials
 The larger the cell the larger the production of waste and need for food.
Limited DNA
 More isn’t created when cell grows
 Not enough “information” to go around
SURFACE AREA TO VOLUME
Volume of a cube –
 L x W x H (X3)
Surface area of a cube –
 H x W x Sides = (6) X2
X3 increases faster then X2 (V increases faster than SA)
 Cells need large surface area and low volume
 Helps diffusion of food and waste in and out
CELL CYCLE
Cells divide to solve problem of becoming too big
Two Parts
1.
Interphase
2.
Mitosis
INTERPHASE
Interphase – period of cell
growth and DNA replication
3 stages
1. Gap “G” 1 – Period of cell
growth, new organelles and
proteins created
2. S – Chromosomes replicate
3. Gap “G” 2 – More organelles
and molecules are created
CHROMOSOMES
Made of DNA
Carries genetic information
Every species has a specific amount of chromosomes
 Humans have 46 chromosomes in each cell
MORE ABOUT CHROMOSOMES
Most of the time – Chromosomes can’t be seen – called Chromatin
When cell is ready to divide – they duplicate and condense
https://www.youtube.com/watch?v=N5zFOScowqo
MITOSIS (REMEMBER PMAT)
4 phases
1.
Prophase
2.
Metaphase
3.
Anaphase
4.
Telophase
PROPHASE
Nucleus disappears
Spindle fibers form (made of microtubles)
Chromosomes are already condensed and
duplicated but still joined at centromere
Each side are sister chromatid
METAPHASE
Chromosomes line up in the middle
Spindle fibers attach to centromere
ANAPHASE
Sister chromatids separate
Pulled apart by spindle fibers
TELOPHASE AND CYTOKINESIS
Nuclear envelope forms around chromosomes
Chromosomes uncondense
Cell membrane pinches in the middle until two
cells form
FINAL RESULTS
2 identical daughter cells are created
Same amount of DNA as original
Return to Interphase G1 Stage
 Cells that are done growing (nerve, heart, etc) enter stage called G0 – no new
divisions
MITOSIS VIDEO
http://youtube.com/watch?v=VlN7K1-9QB0