1. Day 1

2. Homeostasis All living things respond to their environments.
Remember living things are made of cells that contain carbon.
Homeostasis is the maintenance of stable internal conditions in a changing environment.
One way that a cell maintains homeostasis is by controlling the movement of substances across the cell membrane.

4. Intro to membranes Every cell is surrounded by a cell membrane.
The cell membrane protects the cell and helps move substances and messages in and out of the cell.
By regulating transport the cell membrane helps the cell maintain homeostasis.
SEMI PERMEABLE – body guard

6. Membranes Cells are suspended in a fluid environment.
Even cell membranes are fluid.
They are a sea of lipids in which proteins float.
They also provide structural support for the cytoplasm, recognizes foreign material and communicates with other cells.

7. Lipid Bilayer
The cell membrane is made up of a phospholipid bilayer, which consists of a phosphate (hydrophilic/polar) head and a two fatty acid (hydrophobic/nonpolar) tails.
These phospholipids form a double membrane in which both heads are facing out of the cell.
The phospholipids forma barrier through which only small nonpolar substances can pass.

9. Membrane Proteins
Some proteins found within the membrane face out, some face in the membrane, and some stretch across the entire membrane.
Proteins are made of amino acids (some amino acids. are polar and others are nonpolar).
Polar proteins are attracted to the outside water of the membrane while nonpolar proteins are forced inside the membrane.

10. Activity
Use the rest of the Power Point or your book to make a diagram of the phospholipid bilayer. You should also include a legend for each item explaining what it is and it’s function. Parts that should be included are:
Phosphate
Lipid
Layer 1 and 2
Cytoplasm
Enzymes
Surface marker
Transport proteins (channel and carrier)

11. Listen to these songs while you work
Cell membrane song
Enzyme SONG
Cell song

12. Types of Interior Proteins
Cell surface markers
Receptor proteins
Enzymes
Transport proteins

13. Cell Surface Markers Similar to a name tag
A chain of sugar identifies each type of cell
These sugars are attached to the cell surface by proteins called glycoproteins.
Glycoproteins (sugar (glyco is short for glucose) marker= nametag) help cells work together.

14. Cell Surface marker – sugar name tag

15. Receptor Proteins Enable a cell to sense its surroundings
They bind to certain substances outside the cell.
Once they are bound to the substances outside the cell changes within the cell take place.

17. Enzymes
Proteins with in the cell membrane that help with important biochemical reactions inside the cell.
These can be to increase the speed of a reaction or decrease the speed of a reaction.

18. Transport Proteins
Many substances the cell needs cannot pass through the lipid bilayer in between the two phosphate heads.
WHY???
Transport proteins aid the movement of substances that cannot typically pass into and out of the cell through the cell membrane.
What kind of substance would need help?

19. Channel Proteins
Ions, sugars, and amino acids can diffuse through the cell membrane through channel proteins.
These proteins aka pores serve as tunnels through the lipid bilayer.
Each tunnel allows for a specific substance to diffuse through it. This substance has a specific size and charge.

20. Channel – tunnel

21. Carrier Proteins- hand
Transport substances that fit within their binding site.
A carrier protein binds to a specific substance on a specific side of the cell membrane.
This binding causes the substance to change shape.
As the shape changes the protein is moved across the membrane and release on the other side.
This is enzyme activation across the membrane

22. Carrier – Hand