The Cell Membrane: How the cell maintains homeostasis

Transcription

1 The Cell Membrane: How the cell maintains homeostasis

2 Cell Homeostasis Cats hate and are afraid of water. What do you hate or fear? Think of one or two things that you hate. What do you love and what are you attracted to? Think of one or two things that are attractive to you. phobia means fear. Fear of water is hydrophobia. Fear of snakes is Ophidiophobia. Fear of spiders? phile means like. If you like water, you are an hydrophile. If you like snakes you are an ophidiophile. If you like spiders, you are an arachnophile. The cell membrane is composed of two layers of phospholipids. The Outer heads of the phospholipid really like water and are called philic. The area between the membrane layers is made of the phospholipid tails. Tails are afraid of water and are called: phobic.

3 Hydrophylic head (PO4-) and hydrophobic tail behavior

4 Cell membranes are composed of two phospholipid layers. (bilayer)-draw the all blue phospholipid model and label the tails as fatty acid tails and label the circle as the phosphate head:

5 Cell membranes are composed of two phospholipid layers. (bilayer) Take a minute to Label the cell membrane pictured on your notes: Think: Why does your cell need hydrophobic parts of the membrane?

6 The components move!

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8 The cell membrane has two major functions. 1. Forms a boundary between inside and outside of the cell 2. Controls passage of materials into or out of the cell cell membrane outside cell inside cell

9 Consult with a partner and come up with an analogy for something that is like a membrane in that it is fatty and phobic on the inside, but likes water on the outside (hint-something that dissolves easily likes water ALOT)

10 Components move!

11 The fluid mosaic model describes the membrane. Think about definitions for the two words and then we will discuss how this might relate to the cell membrane: FLUID bendable, movable, not solid MOSAIC (puzzle) composed of many pieces

12 The fluid mosaic model describes the membrane because the molecule/compound components or pieces are always moving ( emb.htm

13 There are other compounds embedded in the membrane: label the matching parts on your diagram: example where are the proteins?. cell membrane carbohydrate chain carbohydrate chain protein cholesterol protein protein channel

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15 Analogy So what should the membrane proteins really look like?

16 Cell Homeostasis: Cell Membrane components/parts Macromolecule compounds Proteins Protein Channel Protein Function Membrane proteins: Identification, holds cells together, sends messages. Channel proteins transport materials into and out of the cell. Identification, holds cells together, sends and receives messages Membrane receptor proteins: Are located in cell membrane- Receive chemical signals/ligands from outside the cell. Intracellular receptor proteins: Located inside the cell-receive chemical signals/ligands like hormones. Carbohydrates Carbohydrates Lipids/Fats Lipids/Fats (nonpolar-no charge) Identification, signaling, and sugary glue that holds cell membrane together. Do not mix with water-cholesterol strengthens the cell membrane and phospholipids form the fatty barrier between cell and environment. Controls the passage of materials into and out of the cell.

17 cell membrane The cell membrane is selectively permeable. Allows some, but not all molecules to cross the membrane. Fig THINK: What molecules would you add to this membrane to make it a more functional and a complete mosaic?

18 The cell membrane is selectively permeable. Predict: Which way will the water molecules move? Toward the inside or outside the cell? Why? Check this out: ife.cell.membraneweb/cell-membrane-just-passingthrough/

19 Chemical signals are transmitted across the cell membrane-read page 84 Receptor proteins bind with ligands (chemicals) and change shape. A ligand is a specific signaling molecule that binds with a receptor protein to make something happen.

20 There are two types of receptor proteins. One type: Intracellular receptor protein *THINK: What does Intracellular mean? Ligand moves through the cell membrane to reach receptor protein on inside of cell. Example: hormones: ion.com/sites/ / student_view0/chapter17/ animation intracellular_re ceptor_model.html

21 There are two types of receptor proteins. The 2 nd type of receptor is: membrane protein receptor (integral protein) Ligand on outside of cell binds with a receptor within the cell membrane. Ex: Neurotransmitters, growth factors

22 There are two types of receptor proteins. The 2 nd type of receptor is: membrane protein receptor Label the missing parts: Ligand Receptor

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