homework get lab safety contract signed read chapter 7: membrane structure and function
TRANSCRIPT
Homework
• Get lab safety contract signed• Read Chapter 7: Membrane Structure and
Function
Cell Membrane
Ms. KlinkhachornNovember 15, 2010
AP Biology
Cell Membranes
• Also called the plasma membrane• All cells have cell membranes – can be
compared to the skin on our bodies• Thin film – need to stack 8,000 to equal the
thickness of a page
Plasma Membrane
• It is selectively permeable– Some materials go through the membrane a lot
easier than others– Some materials can’t go through at all
• What kind of materials need to be able to go in to the cell? Go out of the cell?
Other Membranes
• Membranes can also surround organelles– These organelles are membrane-bound – Create compartments within the cell itself that
have different environments
• What type of cell has membrane-bound organelles?
• What are some examples of membrane bound organelles?
Cell Membrane – What’s what?
Membrane Composition
• Membrane composition depends on the type of cell and the kind of organelle
• Membranes are made up of the following:– Phospholipids– Proteins– Carbohydrates/glycoproteins– Cholesterol
What’s in a membrane?
How do these parts behave?
• Fluid-Mosaic Model – states that components of the membrane are able to move two dimensionally without restraint– Membranes are fluid/dynamic.
• Mosaic = collage– membranes are composed of a variety of
components
How can we remember this?
• “Sea” of phospholipids – move about freely, just like water
• Proteins are like boats or icebergs – half in the water, half out
Root Words!
• What do the following root words mean? What are examples of each?– “Hydro”, “Hydr”– “Phobic”, “Phobia”, “Phobe”– “Phile”, “Philic”, “Philia”
DNA – November 16, 2010
1. Why are cell membranes said to be fluid and mosaic?
2. Cell membranes are selectively permeable. Describe what this means, and explain what would happen to your cells if they weren’t permeable.
Who does this look like?
Phospholipids
• Type of lipid– 2 fatty acids (lipids)
make up the tail– Phosphate group makes
up the head
• Use the roots to figure out the characteristics:– Hydrophobic, nonpolar
tails– Hydrophilic, polar heads
Phospholipid Bilayer
• The cell membrane is organized into two layers of phospholipids called the phospholipid bilayer
• It’s like a sandwich
Phospholipid Structure
Head
Tails
Cell Membrane Components
Cholesterol
• Found imbedded in the lipid bilayer between phospholipids
• Also has a hydrophobic and hydrophilic end
Not all cholesterol is bad
• Helps stabilize the membrane
• Prevents the membrane from being TOO flexible
• Also prevents the membrane from being TOO stiff
Cell Membrane Components
Carbohydrates/Glycoproteins
• Carbohydrates are made up of sugar molecules– Good energy supply
• Glycoproteins are when these carbs are attached to the proteins– not actually inside the bilayer
Carbohydrate Function
• Help with cell-cell recognition– Cell’s ability to distinguish neighboring cells– Helps cells figure out how to sort into tissues and
organs– Cell recognize each other based on the
carbohydrates on the surface of the cell membrane
Types of Glycoproteins/Glycolipids
• Glyco = Sugar• Glycoproteins: carbs
bonded to proteins• Glycolipids: carbs bonded
to lipids
Examples
Blood Types: A, B, AB, and O Immune System Rejection
Cell Membrane Components
Proteins
• Proteins control the day-to-day functions of an organism
• Functions of membrane proteins:– Transport materials in and out of the cell– Messenger systems/Cell Signaling– Enzyme activity for chemical reactions– Cell Recognition
Proteins
• Two Main Kinds of Protein– Integral Proteins• Penetrate the hydrophobic
core• Can be transmembrane
– Peripheral Proteins• Not imbedded in the
membrane• Sit on the outside