1. Chapter 7: Cell Membrane (plasma membrane)

2. Review: the Characteristics of Life  Try to come up with as many characteristics you can. Living things…  Reproduce.  Have genetic material.  Grow and develop.  Use materials and energy.  Respond to their environment.  Maintain homeostasis.  Change over time.  Are made up of units called cells.

3. What is a cell?  Smallest unit of living tissue collected together surrounded by a barrier that separates it from the surroundings.  All living things are made up of cells.  Here is a neat animation of relative size of cells and other ‘objects’. Here is a neat animation of relative size of cells and other ‘objects’.

4. Cell Theory  The cell theory states:  All living things are composed of cells.  Cells are the basic units of structure and function in living things.  New cells are produced from existing cells.

5. “Pro” versus “Eu”  Cells fall into two broad categories, depending on whether the contain a nucleus (controls cell’s activities).  Prokaryotic  Does not contain  Eukaryotic  Does Contain

6. Review  If a cell of an organisms contains a nucleus, the organism is a (an)  A. plant  B. eukaryote  C. animal  D. prokaryote

7. Review  In many cells, the structure that controls the cell’s activities is the  A. cell membrane  B. organelle  C. Nucleolus  D. Nucleus

8. Review the Biomolecules  Four main biomolecules found in living things:  Proteins  Various functions throughout cells/organism.  Lipids  Fats, steroids, oils. Doesn’t mix with water.  Function: store energy.  Carbohydrates  Function: main source of energy.  Nucleotides  Function: store genetic information  DNA or RNA

9. Cell Boundaries  The cell MEMBRANE regulates what enters and leaves the cell and also provides protection and support.  All cells have membranes.  Also phospholipid bilayer

10. Cell Membrane

11.  The cell membrane is made up of two layers called the “lipid bilayer”.  The heads of the lipids are on the outsides.  They are hydrophilic (hydro = water; philic = loving).  The tails of the lipids are on the insides.  They are hydrophobic (phobic = fearing/hating)  Studded throughout the membrane are proteins with various functions.

12. Lipids  made of alcohol and carbon  Tails are fatty acid chains  Slight movement to allow water and substances to pass through membrane (simple diffusion no energy)

13. Cell Membrane as a “mosaic”  Carbohydrate chain (glyco)- act like chemical identification cards allowing individual cells to identify one another  Glycoproteins  Glycolipids  Proteins channels and pumps – help move material across the membrane  Integral protein (channel)  Peripheral protein  Lipids bilayer- gives the membrane a flexible structure that forms a strong barrier

14. Polar vs. Non-polar POLAR/NONPOLAR  Polar means that the substance has positive or negative poles. Non-polar does NOT have positive or negative poles.  Polar things like other polar things. Water is polar!!!!!!!!!  Non-polar things like other non-polar things. Oil is non-polar!!!!!!  Selectively permeable- Some molecules can cross the membrane without assistance, most cannot.

15. Review  Cell membranes are constructed mainly of  A. lipid bilayers  B. protein pumps  C. carbohydrate gates  D. free-moving proteins