Cell membrane Bio

Function of cell membrane (all cells)

Controls what enters and exits the cell to maintain an internal balance called homeostasis

what the Lipid Bilayer is made of

2 layers of phospholipids

Structure of cell membrane

Lipid Bilayer

Phosphate head

polar (water loving)

Fatty acid tail

non-polar (water fearing)

What is embedded in membrane?

Proteins

Selectively Permeable Definition

 Allows some molecules in and keeps other molecules out.

Equilibrium

The concentration of water is the same inside and outside of the cell

Concentration Gradient

A difference in the concentration of a substance (high or low concentration)

What are the parts of cellular transport?

Equilibrium and Concentration Gradient

Types of passive transport

Diffusion, Facilitated diffusion, Osmosis

Diffusion

Random movement of particles from an area of high concentration to an area of low concentration (High → Low)

When does diffusion stop?

once all particles are evenly distributed (Equilibrium is reached)

Facilitated diffusion

diffusion of specific particles through transport proteins found in the membrane, transports larger or charged molecules

Ion Channel

a transport protein with a polar pore; ions pass through

Carrier Protein

attach to a molecule on the outside of the cell, transport it across the membrane, release it on the other side

Osmosis

diffusion of water through a selectively permeable membrane

What element moves from high concentrations to low concentrations?

Water

Sodium-Potassium Pump - purpose

transports 3 sodium ions out of the cell and two potassium ions into the cell.

Endocytosis definition

 taking material into a cell

Exocytosis

Forces material out of a cell in bulk, Vesicles in the cell fuse with the cell membrane and release their content

Endocytosis - consumer or disposer?

Consumer of food particles

Exocytosis - consumer or disposer?

Disposer of waste

Hypotonic Solution DEF

The solution has a Low concentration of solutes and a High concentration of water than inside the cell. (Low solute; High water)

Result of Hypotonic Solution

Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)!

Hypertonic Solution DEF

The solution has a High concentration of solutes and a Low concentration of water than inside the cell. (High solute; Low water)

result of Hypertonic Solution

Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)!

Isotonic Solution DEF

The concentration of solute in the solution is equal to the amount of solutes inside the cell.

Result of Isotonic Solution

Water moves in and out of the cell at the same rate and the cell remains the same size! (Dynamic Equilibrium)

Sodium amount

3

Potassium amount

2