Chapter 5:

Ch. 5 Cell Membrane and Transport

LIPID BILAYERcytoplasmextracellularfluidCell Membranethin, flexible membrane that surrounds all cells.

Selectively permeable - regulates what enters and exits the cell.

Made up of a phospholipid bilayer.

Double layer of phospholipids

Gives cells flexible but strong barrier between itself and its surroundings.

Phospholipids are a lipid that have a GlycerolPhosphateTwo fatty acid chainsPhospholipidsHydrophilicheadHydrophobictail

Hydrophilic HeadHydrophobic tail

Phospholipid Bilayerhydrophilicheadhydrophobictails

hydrophilicheadWater (outside of cell)Water (inside of cell) Fluid mosaic model

Fluid mosaic model

Carbohydrate (of glycoprotein)GlycoproteinFibers of extracellular matrixMicrofilaments of cytoskeletonProteinSteroids (cholesterol)PhospholipidGlycolipidPhospholipid BilayerMembrane Proteins> 50 kinds of proteins found in human red blood cells so farCarry out many different functionsStructural, external, identification tags, form junctions between cellsEnzymes catalytic teams for molecular assembly linesReceptors receive chemical messages from other cellsMessage transfer is called signal transductionHelp move substances across membrane

No Gradient Gradient Concentration Gradient: Difference in concentration over a distance.Cell Transport: movement of substances across the cell membrane based on concentration gradient.HIGH concentrationLOWconcentrationHow the Cell Membrane does its thingTwo categories of cell transport:

Passive transport Requires NO energyHigh to low concentration

Active transport Requires energyLow to high concentration

3 types of passive transport:

Simple Diffusion High to low concentrationSmall, lipid soluble molecules like CO2 and O2Example:Oxygen enters bloodstream from the lungs

2) Facilitated DiffusionLarge, charged, or polar substances move across membrane in this way.Always moves from high to low concentrationRequires a transport protein

Transport Protein2) Facilitated DiffusionWater can move through because it is small, buttransport is slow, aquaporins allow for faster diffusion

Transport Protein3) Osmosis:Diffusion of water through a selectively permeable membrane until equilibrium occurs.

High to low concentration

Water will cross membrane until solute concentrations(molecules/mL) are equalon both sides of membrane

What words do you know that start withIso______________Definition: sameHyper___________Definition: above

Hypo____________Definition: belowIsotonic/Isosceles triangle/IsotopeHyperactive/HyperextendHypothermia, Hypodermic needleTonicityA term used to describe the tendency of a cell in a given solution to lose or gain water.

Isotonic SolutionConcentration of solutes is equal in and out of the cell. No net movement of water.Cell maintains shape.

BEFOREAFTERHypertonic SolutionsConcentration of solutesis higher outside the cell. Water exits the cell.

Animal Cell: shrinks which is known as crenation

Plant Cell: cell membrane collapses away from cell wall. This is known as plasmolysis.

D. Hypotonic SolutionConcentration of solutes is lower outside the cell.

1. Water enters the cell.

2. Animal cell swells and may burst which is known as Cytolysis.

3. Plant cellcell wall prevents breaking. (Turgor Pressure)

Animal Cells in a hypertonic:CRENATIONPlant Cells in a hypertonic:PLASMOLYSIS

Hypotonic Isotonic HypertonicRed Blood CellsTonicity in animalsOsmoregulation: or an animal to survive changes in salinity it must have a method to prevent excessive uptake of water or excessive loss of waterEx: freshwater fish live in hypotonic environmentEx: saltwater fish live in a hypertonic environment

Have evolved to have kidneys and gills that constant work to flush water out of the bodyFreshwater Teleost

Marine Teleost

Tonicity in plantsTurgidity: When a plant cell has a net inflow of water.Plasmolysis: When a plant cell loses water, plasma membrane pulls away from cell wall.Also happens in bacteria and fungi

ISOTONIC

HYPOTONIC HYPERTONIC

What type of solution is each cell in?

ISOTONICHYPERTONICHYPOTONICFig. 5.14, p. 88

2M sucrosesolution1 liter ofpure water10M sucrosesolution2M sucrosesolutionHYPOTONICCONDITIONSHYPERTONICCONDITIONSISOTONICCONDITIONS1)2)3)Ticket out Quiz

Active TransportSubstances move against concentration gradient-low to high concentration

Requires energy (ATP)

Requires a transport protein.Ex:

Sodium-Potassium pump in nerve cells

Sodium Potassium Pump in Nerve CellsHow do LARGE molecules enter and exit the cell?BULK TRANSPORT: Movement of particles into or out of a cell without passing through the plasma membrane.Requires energy!

Cell engulfs large materials such as macromolecules.

Endocytosis Large materials move into cell.

PhagocytosisCell engulfs large particles, microbes, and cellular debris

Cell eating

Pinocytosis Cells receive bulk amounts off liquid

Cell drinking

Exocytosis - vesicle fuses with the membrane and exits the cell.

Expels materials such waste and hormones.

Lorenzos OilALDCan not digest FATFat builds up and destroys his nervesFat enters body in 2 ways food and biosynthesisOil stops biosynthesis!Oil keeps the body from building up the bad fatCOMPETITIVE inhibition