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.
