Chapter 5

Hypotonic

Lower concentration of solute in a solution. High water concentration.

Osmosis

The diffusion of water across a semi- permeable membrane. Water moves from high to low concentration. Hypotonic to hypertonic

Simple Diffusion

The movement of substances from high to low concentration. natural, spontaneous and does not require additional energy.

Peripheral proteins

located on the inner or outer surface of the bilayer.

What happens when an animal cell is placed in a hypotonic solution?

water will diffuse into the cell. The cell will swell and burst.

What happens when when phospholipids are placed in water?

A phospholipid bilayer is formed. Heads are in contact with water while tails stay on inside away from water.

functions of membrane proteins: Transporters

Allow only certain substances to pass in and out of the cell.

Turgor Pressure

Causes plant cell to be firm. cell wall prevents bursting.

functions of membrane proteins: Attachment

Connect to ECM, cytoskeleton, etc.

Hypertonic

Higher concentration of solute in a solution. Low water concentration.

Ion Channels

Part of channel proteins; a pore that allows ions to pass through the membrane. Some ion channels can open and close.

Integral proteins

Partially in or fully span the bilayer. ----------l------------ ----------l------------

Coupled Transport

Simultaneous transport of two substances across the cell membrane. Protein actively pumps a substance out of cell; requires energy.

Carrier Proteins

Protein binds to a specific substance and helps it through the membrane. Sugar and amino acids are transported via carrier proteins.

Soduim Potassium Pump

Pumps 3 sodium ions (Na+) out of the cell and 2 Potassium ions (K+) into the cell. Requires energy. As a result there is a high K+ and a low Na+ inside cell.

Active Transport

Requires energy; doesn't occur naturally, low-->high

Passive Transport

Requires no energy; occurs naturally. high--> low consists of: a. simple diffusion b.Faciliated Diffusion c. Osmosis

functions of membrane proteins: Signal Transduction

Respond to environment.

Channel Proteins

Same as a pore "a tunnel"

Faciliated Diffusion

Same as simple diffusion except a protein helper is required to assist a substance across the membrane.

Isotonic

Same concentration of solute.

functions of membrane proteins: Enzymes

Speed up chemical reactions.

Plasmolysis

The cell membrane will pull away from the cell wall. Happens when a plant cell is placed in a hypertonic solution.

Solute

The substance that is dissolved in the solvent.

What happens when a plant cell is placed in a hypotonic solution?

Water diffuses into cell. water is stored in the vacuole causing it to expand and exert pressure on the cell wall.

Crenation

Water diffusing out of an animal cell.

What happens when a cell is placed in an isotonic solution?

Water molecules enter and exit cell at a constant rate. Animal cells are normal. PLant cells become limp.

What happens when a plant cell is placed in a hypertonic solution?

Water will diffuse out of cell. Vacuole and cytoplasm will shrink due to the loss of water.

What happens when an animal cell is placed in a hypertonic solution?

Water will diffuse out. The cell will probably die.

Hemolysis

When a animal cell is placed in a hypotonic solution. cell burts because water diffuses into cell.

Solution

a mixture of a solvent and another substance.

functions of membrane proteins: Cell-cell recognition

act as an ID badge

functions of membrane proteins: Intercellular joining

attach to other cells.

Phospholipid Bilayer

quite flexible and not rigid. saturated= less flexible; unsaturated= more flexible cholesterol molecules within membrane reduce flexibility.