Agenda 9/29Agenda 9/29

Cell Organelle QUIZCell Organelle QUIZ Pass back biomolecule quizPass back biomolecule quiz

– Discuss corrections and retakes for Discuss corrections and retakes for those who failed to get to a 70 possibly.those who failed to get to a 70 possibly.

Notes: The Cell Membrane and Notes: The Cell Membrane and Transport.Transport.

Homework over the cell membrane Homework over the cell membrane due next class.due next class.

The Cell Membrane The Cell Membrane and Transportand Transport

ObjectiveObjective

Identify, investigate and explain Identify, investigate and explain cellular processescellular processes– Transport of molecules across the cell Transport of molecules across the cell

membranemembrane

Three namesThree names

Phospholipid bi-layerPhospholipid bi-layer Cell membrane Cell membrane Plasma membranePlasma membrane

What does the cell membrane do?What does the cell membrane do?

Regulates what enters & leaves the Regulates what enters & leaves the cell cell

Provides protection Provides protection Provides supportProvides support

GOAL: HOMEOSTASISGOAL: HOMEOSTASIS

What does the cell membrane look What does the cell membrane look like?like?

How does the cell membrane How does the cell membrane regulate what enters and leaves the regulate what enters and leaves the

cell?cell? Semi-permeableSemi-permeable – Lets some things in and out – Lets some things in and out

of the cell, but not all thingsof the cell, but not all things

Passive Transport – does NOT require energyPassive Transport – does NOT require energy

Active Transport – does require energy (ATP)Active Transport – does require energy (ATP)

Passive Transport - DiffusionPassive Transport - Diffusion

Movement of particles (food) from Movement of particles (food) from HIGHHIGH concentration to concentration to LOWLOW

Goal = Goal = equilibriumequilibrium or balance of or balance of molecules both inside & outside the molecules both inside & outside the cell (HOMEOSTASIS)cell (HOMEOSTASIS)

Molecules flow through the lipid bi Molecules flow through the lipid bi layerlayer

What does diffusion look like?What does diffusion look like?

Passive Transport – Facilitated Passive Transport – Facilitated DiffusionDiffusion

For molecules that are too big to For molecules that are too big to diffuse directly through the cell diffuse directly through the cell membranemembrane

What is Facilitated Diffusion?What is Facilitated Diffusion?

Membrane proteinsMembrane proteins will allow some will allow some molecules (like sugar) in or out of the molecules (like sugar) in or out of the cell that are too big to easily diffuse cell that are too big to easily diffuse through the cell membrane.through the cell membrane.

Still moving from a Still moving from a highhigh concentration to a concentration to a lowlow concentration…concentration…

NO ENERGY REQUIRED!NO ENERGY REQUIRED!

Every time a cell’s environment Every time a cell’s environment changes…changes…

Water is moving from a Water is moving from a higherhigher concentration to a concentration to a lowerlower concentration.concentration.

The name of this process is…The name of this process is…

OsmosisOsmosis

The diffusion of water. The diffusion of water. Just like the iodine diffused across Just like the iodine diffused across

the dialysis membrane, water moved the dialysis membrane, water moved across the egg’s membrane.across the egg’s membrane.

ObjectiveObjective

Identify, investigate and explain Identify, investigate and explain cellular processescellular processes– Transport of molecules across the cell Transport of molecules across the cell

membranemembrane

Active Transport Active Transport

Movement across the cell membrane Movement across the cell membrane from a LOW concentration to a HIGH from a LOW concentration to a HIGH concentrationconcentration..

Requires energy (ATP)Requires energy (ATP) One type uses One type uses membrane proteinsmembrane proteins to to

push large molecules across the semi push large molecules across the semi – permeable cell membrane.– permeable cell membrane.

What does Active Transport look What does Active Transport look like?like?

Image from “The Virtual Cell Textbook” http://www.ibiblio.org/virtualcell/textbook/chapter3/cmf1c.htm

Endocytosis, ExocytosisEndocytosis, Exocytosis

endo: insideendo: insideExo: outsideExo: outsideCyto: cellCyto: cell

Help for the large: Both designed Help for the large: Both designed to move a to move a large substance large substance or a or a large amount of substancelarge amount of substance..

The cell membrane is flexible and can change shape to form a The cell membrane is flexible and can change shape to form a pocket.pocket.

Both require energy (ATP)Both require energy (ATP)

Cell Transport: Moving Across the Cell Cell Transport: Moving Across the Cell MembraneMembrane

EndocytosisEndocytosis The membrane folds inward, surrounds the material, and The membrane folds inward, surrounds the material, and

then fuses together.then fuses together. The bubble created with The bubble created with

materials is called a materials is called a vesiclevesicle.. Materials are usually Materials are usually

transported to the lysosome.transported to the lysosome.

ExocytosisExocytosis Vesicle transported to cytoplasm, vesicle fuses with cell Vesicle transported to cytoplasm, vesicle fuses with cell

membrane, and then releases its contents outside the cellmembrane, and then releases its contents outside the cell

Cell Transport: Moving Across the Cell Cell Transport: Moving Across the Cell MembraneMembrane

ObjectiveObjective

Identify, investigate and explain Identify, investigate and explain cellular processescellular processes– Transport of molecules across the cell Transport of molecules across the cell

membranemembrane

Osmosis and TonicityOsmosis and Tonicity

Tonicity refers to the total solute Tonicity refers to the total solute concentration of the solution concentration of the solution outside the cell.outside the cell.

What are the three types of tonicity?What are the three types of tonicity?

1)1) Isotonic - equalIsotonic - equal

2)2) Hypotonic – lower; underHypotonic – lower; under

3)3) Hypertonic – higher, overHypertonic – higher, over

IsotonicIsotonic concentration of concentration of water (solvent) outside the cell water (solvent) outside the cell

is the is the same same as the concentration as the concentration inside the cellinside the cell..

What will happen to a cell placed in an What will happen to a cell placed in an Isotonic solution?Isotonic solution?

The cell will have no net movement The cell will have no net movement of water and will stay the same size.of water and will stay the same size.

Ex. Blood plasma has high Ex. Blood plasma has high concentration of albumin molecules concentration of albumin molecules to make it isotonic to tissues.to make it isotonic to tissues.

HypotonicHypotonic concentration of water (solvent) outside the cell is concentration of water (solvent) outside the cell is

higherhigher than the concentration inside the cell. than the concentration inside the cell.

What will happen to a cell What will happen to a cell placed in a Hypotonic solution?placed in a Hypotonic solution?

The cell will gain water and swell.The cell will gain water and swell.

If the cell bursts, then we call this If the cell bursts, then we call this lysislysis. (Red blood cells = hemolysis). (Red blood cells = hemolysis)

In plant cells with rigid cell walls, this In plant cells with rigid cell walls, this creates creates turgorturgor pressure. pressure.

HypertonicHypertonic concentration of water (solvent) outside the concentration of water (solvent) outside the

cell is cell is lowerlower than the concentration inside than the concentration inside the cell.the cell.

What will happen to a cell What will happen to a cell placed in a Hypertonic solution?placed in a Hypertonic solution? The cell will lose water and shrink. The cell will lose water and shrink.

In plant cells, the central vacuole will In plant cells, the central vacuole will shrink and the plasma membrane will shrink and the plasma membrane will pull away from the cell wall causing pull away from the cell wall causing the cytoplasm to shrink called the cytoplasm to shrink called plasmolysis.plasmolysis.

Review TonicityReview Tonicity What will happen to a red blood cell in a hypertonic What will happen to a red blood cell in a hypertonic

solution?solution? What will happen to a red blood cell in an isotonic solution?What will happen to a red blood cell in an isotonic solution? What will happen to a red blood cell in a hypotonic What will happen to a red blood cell in a hypotonic

solution?solution?

Eggs-periment Eggs-periment

The egg without its shell is a The egg without its shell is a cell cell with a semi-permeable with a semi-permeable membranemembrane

Cell in Distilled WaterCell in Distilled Water

What will happen and WHY????What will happen and WHY????

Cell in Corn SyrupCell in Corn Syrup

What will happen and WHY????What will happen and WHY????

ObjectiveObjective

Identify, investigate and explain Identify, investigate and explain cellular processescellular processes– Transport of molecules across the cell Transport of molecules across the cell

membranemembrane