Cell Biology
The big picture
Important questions
What are cells?
 Why are they important?
 What’s the purpose of cells?
 What’s inside a cell?

What are cells
Cells are the basic unit of structure and
function of living things.
 You are made of trillions of specialized
cells all working together.

Why are cells important
Cells help keep living things alive
 Some of the functions of cells are:

–
–
–
–
Obtaining oxygen
Getting rid of wastes
Obtaining food
Growth, repair, and reproduction
What’s the purpose of cells

Cells help us stay alive and reproduce
– Cells in your lungs provide oxygen for your
body
– Cells in your stomach provide energy by
digesting food
– Cells in your muscles protect your weaker
organs
What's inside a cell

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Mitochondria
Cytoplasm
Ribosomes
Nucleus
Endoplasmic
Reticulum
Golgi Body
Cell membrane
Vacuole
Lysosomes
Nucleus

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The nucleus is the
“brain” of every cell
Every cell has a nucleus
Chromosomes are found
inside the nucleus
Candy Question

In your groups answer the following
question.

One square centimeter of your skin’s
surface contains more than
100,000
________________
cells.
Purpose of cell division
The purpose of cell division is to take one
cell and make two new identical “daughter”
cells.
Cells need to divide for reproduction, growth,
and for repair.
Two types of cell division
Mitosis Meiosis
Mitosis
Mitosis happens in order to create new
identical cells
 Majority of cells under-go mitosis
 Main purpose of mitosis is growth and
repair

Mitosis
46
92
46
Parent Cell
DNA replicates
46 x 2 = 92
46
Two new identical daughter cells

Prophase
– Chromosomes become visible, the
nucleolus disappears.

Metaphase
– The chromosomes become arranged in the
center of the cell.

Anaphase
– Chromosomes separate and then move to
opposite sides of the cell.

Telophase
– Chromosome reassemble at opposite sides
of the cell and the nucleus reforms,
around each set of chromosomes.
Meiosis
Meiosis only occurs in sex cells
 The only purpose for meiosis is for
reproduction
 The result of meiosis is four new cells with
HALF the number of chromosomes.

Meiosis
46
Parent Cell
DNA replicates
92
46
23
DNA splits
46
23
23
23
DNA splits again
Compare and Contrast
Mitosis and Meiosis
Alike


Both are cell reproduction
to make new cells
Both go through similar
phases
Different


Mitosis results in two new
cells which has 46
chromosomes and happens
in most cells.
Meiosis results in four
new cells which has 23
chromosomes and happens
only in sex cells.
Meiosis
Mitosis
46
46
92
92
46
23
46
23
23
46
23
46
Using the plastic chips show me:
Mitosis
Meiosis
If you break your arm, what cell division
takes place to repair the bone in your arm?
Which cell division creates human
reproduction cells?
Represents the number of chromosomes
92
46
23
Review