1. 2-4 Looking Inside Cells

2. Parts of the Cell
Cells (which you remember are the smallest unit of structure and function in the body) contain smaller structures called organelles.
Organelles carry out specific functions in the cell much as organs like the heart and lungs carry out functions in your body.

3. From Outside In
Plant cells (unlike animal cells) have a rigid layer of non-living material surrounding the cell called a cell wall. The cell wall acts like the plants skeleton giving it support.
Inside this plant cells have a cell membrane. Animal cells outermost layer is the cell membrane.

4. Cell Membrane
All cells have cell membranes. It acts like the skin of the cell.
The main function of the cell membrane is to control what substances come into and out of a cell.
Things cells need like oxygen, water, and food enter through the cell membrane while waste products like carbon dioxide leave through it.

5. Nucleus
In the center of the cell is a large oval structure called a nucleus.
The nucleus acts like the cells “brain”- it is the control center of the cell directing all of its activities like growth and reproduction.
It is filled with a substance called chromatin. Chromatin contains genetic material, the instructions that direct the functions of the cell. For example, it tells the cell how to grow.

6. Cytoplasm
The region between the cell membrane and the nucleus is filled with a jelly-like substance called cytoplasm.
Most cell organelles are found floating in the cytoplasm.
These organelles function to produce energy, build and transport needed materials, and store and recycle wastes.

7. Mitochondria
Mitochondria are bean-shaped organelles in the cell’s cytoplasm that are called the “powerhouse” of the cell because they produce most of the energy the cell needs to carry out its functions.

8. Endoplasmic Reticulum
The E.R. is a maze-like collection of passageways surrounding the nucleus.
They carry proteins and other materials from one part of the cell to another.

9. Ribosomes
Ribosomes are small, round structures found throughout the cytoplasm.
They function as protein factories
They pass these proteins on to the endoplasmic reticulum. From inside the e.r., they are transported to the golgi bodies.

10. Golgi Bodies Golgi Bodies are a flattened bunch of sacs and tubes.
Act like a mailroom. They receive proteins from the e.r. and distribute them to other parts of the cell and even outside the cell.

11. Chloroplasts
Chloroplasts are found only in plant cells (and some bacteria).
Their function is to capture the sun’s energy and use it to produce food as energy.
Their pigments make the plant green.

12. Vacuoles Vacuoles are large sacs filled with water.
They act as the cell’s water storage tanks.
Most plants have them, some animal cells do, some don’t

13. Lysosomes
Lysosomes are small round structures containing chemicals that break down food and old cell parts.
They act like the cell’s cleanup crew.

14. The other Cell Type: Bacteria
Bacteria cells are much smaller than most animal or plant cells.
Bacteria like plants, do have cell walls and cell membranes.
But bacteria do not have a nucleus and except for ribosomes, none of the other organelles found in animal and plant cell.

15. Prokaryotes and Eukaryotes
Cells (like bacteria) that have no nucleus are called Prokaryotes (which means “before the nucleus” because its thought they evolved earlier in time before more advanced cells).
Cells that do have a nucleus (like plant and animal cells) are called Eukaryotes which means “has a nucleus.”