EQ: What are the basic parts of cell membranes, and what is the job of each

part? Can I diagram diffusion of oxygen, facilitated diffusion of

glucose, and osmosis across a cell membrane?

BOUNDARY OF THE CELL:Cell: smallest unit that can carry out all the activities for life. (the “atom” of biology)Cell Membrane Diagram:

Outside of cell

Inside of cell (cytoplasm)

Cellmembrane

Proteins

Proteinchannel Lipid bilayer

Carbohydratechains

Membrane Descriptives:• Semi-Permeable—certain molecules can pass through the membrane, but not all molecules can

Fluid Mosaic Model—Proteins “float” in a fluid or moveable layer of phospholipids

Components of the Cell Membrane***Reference the image on slide #2***

• Phospholipid bilayer—• phospholipids have a phosphate head (yellow

circle) • lipid tails (the brown tails). • The phosphate heads line up on the outside

because they are hydrophilic (water-loving). • The lipid tails line up on the inside because they

are hydrophobic (water-hating).

• Proteins—act as channels or pumps to help molecules pass through the membrane

• Carbohydrate chains—help cells recognize and communicate with each other

Solution terms: we discussed this during basic chemistry notes…Solution – mixture of solute and solvent

(Ex. Kool-Aid = powder + water)

Solute – substance being dissolved (ex. Kool-Aid powder, Salt, or sugar)

Solvent – substance dissolving solute (ex. Water, which is a universal Solvent)

Membrane trafficPassive transport~ diffusion of a substance across a biological membrane (NO ENERGY needed)Ex. 1 Diffusion~ the overall movement of particles from a region of high concentration

to an area of low concentrationEx. 2 Osmosis~ the diffusion of water across a selectively permeable membrane

Concentration: the relative amount of a given substance contained within a solution or in a particular volume of space; the amount of solute per unit volume of solution.

Results of DiffusionDynamic equilibrium

Once diffusion has evenly distributed the solute throughout the solvent, movement of particles continues with no change in concentration

HomeostasisPreservation of equilibrium

Diffusion depends on concentration gradient:Concentration gradient: the difference in concentration of a substance across space

Diffusion is said to move down a concentration gradient

Diffusion continues until there is NO concentration gradient

Ex: O2 diffuses into oxygen depleted blood

Diffusion Rules:

QuickTime™ and aCinepak decompressor

are needed to see this picture.

Small Molecules like WATER,

OXYGEN, AND CARBON DIOXIDE

CAN MOVE in and out freely.

Large molecules like PROTEINS

AND CARBOHYDRATES CANNOT

Charged IONS CANNOT

Osmosis~ the diffusion of water across a selectively permeable membrane.

Water likes to DILUTE high concentrations of solute

Osmosis in the Real WorldBryophytes, or mosses, are plants that depend on osmosis transfer water from the environment into the plant.

Bryophytes can never grow tall, because they cannot pull the water against gravity just using the concentration gradient.

Bryophytes must also live in wet environments

Review:Osmosis is the diffusion of _______ across a cell membrane.

Osmosis and Diffusion are both types of __________ transport.

Passive transport does or does not require energy?

Small molecules can not move across freely. T or F

Large molecules can move freely. T or F

Three Different Types of SolutionsIsotonic Solution

Hypotonic Solution

Hypertonic Solution

Isotonic SolutionThe solute outside the cell is equal in concentration to the solute in the cell.

The cell retains its shape.

water moves equally in both directions (into and out of the cell) Normal

looking cells

Hypotonic Solutions

Solution outside the blood cell contains a lower concentration of solute than inside of the cell.

Water will diffuse inside the cell. cell will lyse (burst).

In Animal cells - cytolysis. Plant cells do not burst- turgur pressure— grocers use this idea

Cells in a Hypotonic Solution

Hypertonic SolutionsThe solution outside the cell has a higher concentration of solute than inside of the cell.

Water will diffuse out of the cell, causing the cell to shrink or crenate

Why should you not salt meat before cooking?

CRENATION PLASMOLYSIS

Cells in a Hypertonic Solution

In what type of solution would these cells be found?

Water Balance SummaryOsmoregulation~ control of water balance

Hypertonic~ higher concentration of solutes

Hypotonic~ lower concentration of solutes

Isotonic~ equal concentrations of solutes

Plasmolysis Turgidity in plant cells.

QuickTime™ and aCinepak decompressor

are needed to see this picture.

QuickTime™ and aCinepak decompressor

are needed to see this picture.

What type of solution is this?Hypertonic

What will happen to the cell? It will shrink.