Download 1.3 Cells from Cells

1.3 Cells from Cells
Cell from Cells
 Recall: From the cell theory we established
that all cells come from pre existing cells.
 Cell Reproduction: the process by which
new cells are forms.
Purpose of Cell Division
 Allows organisms to do three things:
Grow
Repair
Reproduce
Cell Division
 Cell Division: the process by which a parent cell
divides into two daughter cells.
 What is the importance of cell division?
 You started as a single fertilized egg  now you have
trillions of cells. How?
 Cell division! new cells have constantly been forming
as you grow.
Cell Division for Growth

Every cell faces the problem of needing enough
surface area to service its volume.

As something gets bigger, the ratio of surface
area to volume decreases.

When a cell gets too big:
 Nutrients and water cannot move through it fast enough.
 Wastes cannot exit fast enough.

So then what happens?
 Cell Division! It must produce smaller cells = more surface area.
The Cell Membrane and Diffusion

The cell membrane plays a major role in the survival of cells by determining
what it allows in and out of cells.

For example: when you breathe you take
in oxygen and this gets delivered to every
cell in your body.
 How does this access the inside of the
cell?

Diffusion! The movement of molecules
from areas where there are high
concentrations to areas where there are
low concentrations.
Osmosis

The diffusion of WATER from an area of high concentration across a
membrane.
Semipermeable Membrane
The cell membrane has a selectively
permeable membrane:
Some things are
allowed
in and some
things are not
Cell Division for Repair

Everyday your body
sheds millions of
dead skin cells.

These are replaced
by new cells.

Ex. RBC get replaced
every 120 days.

Ex. If you break a
bone, bone cells are
formed to heal the
break.
The end …
Thank you!!
PLEASE FILL OUT THE EXIT PASS
1.
STOP
2.
START
3.
CONTINUE