Bio Cell Membrane

Cell membrane

semi-permeable barrier that separates and protects the interior of all cells from the outside environment

Semi permeable (aka selectively permeable) definition

it allows certain substances to pass through it but not others

What type of cells have a cell membrane?

all cells

What is the cell membrane made up of and what does it create?

• Phospholipids

• Cholesterol

• Carbohydrates

• Proteins

  It creates a phospholipid bilayer

What do phospholipids consist of?

• a hydrophilic head

• a hydrophobic tail

What do the hydrophilic heads in phospholipids face?

the aqueous or watery environment on either side

What do the hydrophobic tails in phospholipids do?

they hide away from the water between the layers of heads

The cholesterol is a type of what?

Steriod (lipid = hydrophobic = nonpolar)

What does the cholesterol do for the cell?

Provides stability by holding phospholipids together

What do carbohydrates hold?

adjoining cells together

What are carbohydrates the site for?

attachment for messengers such as hormones

Where are carbohydrates found?

outside surface of the cell

2 types of proteins

• Integral proteins

• Peripheral proteins

Integral proteins

• Extend across the membrane

• Main source of transporting larger molecules, like glucose, across the cell membrane

Peripheral proteins

• Do not extend across the membrane

• Help with transport or communication

What does the fluid mosaic model describe?

the behavior and structure of the cell membrane

Mosaic

many little pieces (components) that make it up

Fluid

membrane is NOT rigid. It is floaty, loose, wavy, and it jostles

What is the main function of the cell membrane?

• Lets molecules in and out of the cell

• Provides protection for the cell

Without cholesterol the cell membrane can be...

too cold or too hot

Too cold means:

• rigid

• not as flexible

• may break

Too hot means:

• too flexible

• won't hold shape