BIO CH 7

Fluid Mosaic Model

1973 singer and nicolson model

Why is the “fluid mosiac” model called “fluid”

Cell membranes are like Fluid.

Their cell membranes are fluid

How can Amoeba engulf/phagocytize other cells?

Lateral Movement of the Phospholipid Bilayer

The Phospholipid Bilayer moves side to side like an accordion and allows brief periods of gaps in the cell membrane

Flip Flopping movement of a cell

Movement of a cell from one side of the membrane to the other

Lateral movement, flip flopping, presence of cholesterol, and presence of unsaturated fats

What is the reasons the cell membrane is considered a fluid?

Intergral Proteins

Integrated within the phospholipid bilayer, can be amphipathic,

Trans Membrane Protiens

Most important, “transit” stick out above and below the membrane, can be amphipathic

Trans, Peripheral, Intergral

three proteins of the cell membrane

Peripheral proteins

on the top and bottom of the cell membrane

Transmembrane

Transport proteins are also often _____ proteins

Cell to Cell recognition

Function of the membrane proteins, some proteins are only there to fit one cell to another like pieces of a puzzle

Channel and Carrier

Two kinds of Transport Proteins

Channel Proteins

A transmembrane proteins that has a hydrophilic groove or ‘Channel” down the center of the protein. The hydrophilic tendency of the channel allows for the channel to break down and move anything with a charge, water, ions, glucose, etc.

hydrophilic

The channel of a channel protein is highly ______

To allow charged molecules to pass the cell membrane. Without them, the hydrophobic part of the bilayer would stop the movement.

Why are channel proteins necessary?

Aquaporins

A special kind of channel protein specifically for water.

Carrier Protein

A protein which opens and closes on both sides to move/flip the material across the membrane, requires ATP, Active Transport

The Permeability of the Phospholipid Bilayer

non-polar molecules (such as CO2 and O2) can dissolve and cross the lipid bilayer easily without the aid of proteins. Polar molecules cannot easily pass and need the help of proteins.

Diffusion, Active Transport, and Electrical Charges

Mechanisms that drive movement of materials across cell membranes

Diffusion

Passive physical process by which a substance moves down its own concentration gradient from high to low until equilibrium is reached.

Osmosis

The diffusion of water

Tonicity

The ability of a surrounding solution to move fluid into or out of a cell

Crenation

Red blood cells in hypertonic solution shrivel and die

Hypotonic solution

Less solute than the salt contained in the cell

Lysis

when a cell bursts

Red blood cells Lyse or Burst in

Hypotonic solution.

Plant cells become Turgid in

Hypotonic solution

0.9 % Saline

The isotonic environment for humans

Plasmolysis

Cell membrane of a plant cell pulls away from the cell wall, shinking and dying.

Plant cell undergoes plasmolysis in

hypertonic solution

Wilted

In isotonic solution, a plant cell becomes

Sodium Potassium Pump

3Na+ go out of the cell 2 K+ go into the cell the pump is a carrier protein.

Exocytosis

Excretion out of the cell

Pinocytosis

cell drinking

Phagocytosis

cell eating

Ligands

Targets that receptor mediated endocytosis looks for (things that need to be taken from the blood into the cell.)

Cholesterol

Example of a ligand