What is a cell?
A cell is the smallest unit of life.
The cell theory states:
● All living things are made up of cells
● Cells are the basic units of structure and function in living things
● New cells are produced from existing cells

1. The basic unit of life is the cell. (Hooke)
• In 1665, an English scientist named Robert Hooke made an improved microscope and viewed thin slices of cork viewing plant cell walls
• Hooke named what he saw
"cells"

2. All living things are made of 1 or more cells.
• Matthias Schleiden (botanist studying plants)
• Theodore Schwann (zoologist studying animals) stated that all living things were made of cells
Schleiden
Schwann

3. All cells divide & come from old cells. (Virchow)
Virchow

• The long extensions that reach out in various directions from the nerve cell allows the cell to send and receive nerve impulses(messages)
• The flat, plate-like shape of skin cells suits their function of covering and protecting the surface of the body.

• Small cells can exchange substances(oxygen, nutrients, and carbon dioxide) more readily than larger cells because small objects have a higher surface area to volume ratio.
• So, the cells divide!

There are 2 kinds of cells:
• Eukaryotes – Have a nucleus
• Prokaryotes – Do
NOT have a nucleus
• Examples of eukaryotes are plants, animals, fungus, and protists
• More complicated
• Examples of prokaryotes are bacteria
• Smaller than eukaryotes
• Less complicated

• No ______________
• No _________________________
• Examples: Bacteria
• Prokaryotic cells include the following features:
– Smaller in size
– DNA in a nucleoid region
– Cell membrane
– Ribosomes
– Cell wall of peptidoglycan

• Have _____________________
• Have _______________
• Larger than Prokaryotic Cells
• Examples:
– animal cells,
– plant cells,
– fungi cells and
– protist cells

Cells have specialized structures to carry out functions. These are called organelles .

Cell Organelles:
• Nucleus – command center of the cell.
Contains the cell’s genetic material in the form of DNA. ONLY
FOUND IN
EUKARYOTES
• Cytoplasm – the “gel” material inside the cell membrane but not in the nucleus. The organelles live inside the cytoplasm.

Cell Organelles:
• Endoplasmic Recticulum (ER) – makes lipids, proteins and other materials that are exported (taken out) of the cell.
• Rough ER – part of the ER that makes proteins.
Called “rough” because ribosomes are attached to the surface and makes it look bumpy.
• Smooth ER – part of the ER that makes lipids and contains enzymes. Also plays a role in the detoxification of drugs. Ex.) Liver cells play a key role in detoxifying drugs, so they contain large amounts of Smooth ER.
Called “smooth” because ribosomes are not attached to the surface.

• Ribosomes – small particles of RNA and protein found throughout the cytoplasm. They produce proteins by following instructions that come from the nucleus.

Cell Organelles:
• Golgi Apparatus – modifies, sorts and packages the proteins that come from the Rough ER and either stores them or ships them out of the cell.
• Lysosome – removes waste from the cell.

• Vacuoles – saclike structures used to store materials such as water, salts, proteins, and carbohydrates.

• Mitochondria – converts food into energy that the cell can use. They are the power centers of the cell.
• Cytoskeleton – supports the cell and helps to maintain the shape.

Cell Organelles
• Cell membrane – regulates what enters and leaves the cell and also provides protection and support.
• Centriole -located near the nucleus and helps organize cell division . Not found in plant cells.

• Nuclear membrane surrounds the nucleus and allows material to move in and out of the nucleus.
• Nucleolus within the nucleus, where the assembly (making) of ribosomes begin.

Cell Organelles:
•
Chloroplasts – ONLY
FOUND IN PLANT
CELLS
- captures energy from sunlight and converts it into chemical energy in plant cells.
• Cell Wall – ONLY
FOUND IN PLANT
CELLS
- provides support and protection for the plant cell.

• Peroxisomes—absorb nutrients, digest fatty acids, and alcohol
-breakdown toxic hydrogen peroxide to water