7.2 PLASMA MEMBRANE

7.2 THE PLASMA MEMBRANE WHAT YOU WILL LEARN: -how a cell’s plasma membrane functions -the roles of proteins, carbohydrates & cholesterol in the plasma membrane

READING QUESTIONS 1-HIGHLIGHT the items in the figure that enter the cell thru pm/CIRCLE those that exit the cell oxygen glucose water

READING QUESTIONS 2-EXPLAIN the purpose of phospholipid bilayer? -allows plasma membrane to survive & function in its watery environment

READING QUESTIONS 3-IDENTIFY: CIRCLE one phospholipid—LABEL its head/tail head tail

READING QUESTIONS 4-DEFINE the role of transport proteins 5-NAME 3 substances that move among the phospholipids of the PM -move substances through plasma membrane -proteins/carbohydrates/cholesterol

http://www.dnatube.com/video/360/Fluid-Mosaic-Model http://www.susanahalpine.com/anim/Life/memb.htm

REVIEW -homeostasis: -maintain balance / internal environment 7.2 THE PLASMA MEMBRANE REVIEW -homeostasis: -maintain balance / internal environment http://www.dnatube.com/video/360/Fluid-Mosaic-Model

FUNCTION of the PLASMA MEMBRANE selective permeability-- -CONTROLS substances ENTER / LEAVE (homeostasis) WHAT WHEN HOW *cells must keep proper concentration of nutrients / water / expel waste -some molecules can cross the plasma membrane --(water) -others must go through channels --(Na, Ca, etc) This is like a FISH NET--HOW? T/P/S: analogy for a cell’s selective permeability

FUNCTION of the PLASMA MEMBRANE FUNCTION of PLASMA MEMBRANE -boundary separates cell & environment -allows water, nutrients & oxygen into cell -allows waste & CO2 out of cell OUTSIDE CELL NUTRIENTS OXYGEN WATER CARBON DIOXIDE WASTE INSIDE CELL

STRUCTURE of PLASMA MEMBRANE polar head— hydrophilic …likes water non-polar tail— hydrophobic …repels water

STRUCTURE of PLASMA MEMBRANE

STRUCTURE of PLASMA MEMBRANE A- carbohydrate chain C- polar heads B- transport  protein E-cholesterol  D- non-polar tails

STRUCTURE of PLASMA MEMBRANE B- lipids C- phospholipid A- transport protein F- phospholipid bilayer D- fluid mosaic model E- selective permeability

FUNCTION of the PLASMA MEMBRANE DESCRIPTION SELECTIVE PERMEABILITY HOMEOSTATSIS PLASMA MEMBRANE 1-The process of maintaining balance inside a cell. 2-A boundary between a cell & its environment. 3-Feature of plasma membrane that keeps some substances out. 4-Separates prokaryotic & eukaryotic cells from the watery environment in which they exist 5-The quality of a plasma membrane that allows oxygen & glucose to move in 6-Maintained by the plasma membrane

Diagram representing the cell membrane. The above image is from http://www.biosci.uga.edu/almanac/bio_103/notes/may_15.html. But I found it at An On-Line Biology Book: http://gened.emc.maricopa.edu/bio/BIO181/BIOBK/BioBookCELL2.html

STRUCTURE of PLASMA MEMBRANE -polar heads barrier to water environment in/out of cell -non-polar tails prevent substances dissolve in water from passing thru PM -carbohydrate chain identify chemical signals from environment -cholesterol prevent tails from sticking together, keep membrane fluid -transport protein like tunnels--move materials thru plasma membrane -membrane protein receptors—on outside, send signals to inside of cell anchors—on inside, hold membrane to cell’s internal shape

STRUCTURE of PLASMA MEMBRANE EXPLAIN/DRAW 1-MEMBRANE PROTEIN -create tunnels -PASSIVE 2-TRANSPORT PROTEIN -”pump” substances / ACTIVE

STRUCTURE of PLASMA MEMBRANE EXPLAIN/DRAW CHOLESTEROL -non polar -keeps PM fluid--prevents fatty acid tails from sticking -maintains homeostasis in cell CARBOHYDRATE CHAIN -help cell identify chemical signals from environment

FLUID MOSAIC MODEL This “MODEL” for the structure of the membrane is called the: FLUID MOSAIC MODEL FLUID- individual phospholipids / proteins move freely within the layer-- like a liquid MOSAIC- “pattern” produced by the scattered protein molecules

Cell Membranes from Opposing Neurons (TEM x436,740). Nerve cell Gap between cells Cell membrane { } cell membrane 7nm wide Nerve cell AS Biology. Foundation. Cell membranes and Transport