Objective Here!

Where do you find roads without vehicles, forests without trees, and cities without houses?

Which numbered organelle produces ATP and is called the Powerhouse of the cell?

A) 1B) 7C) 9D) 13

Maintaining control of the internal environment

The structure of the plasma membrane

How the plasma membrane functions as a semi-permeable membrane

The membrane separates the organelles of the cell from the outside environment

It is made of a double layer of phospholipids and embedded proteins.

Controls what enters and leaves the cell. Nutrients Waste

It is said to be selective permeability (Everything CANNOT enter the cell)

Water can freely enter and leave the cell

Maintains homeostasis

What does the plasma What does the plasma membrane do?membrane do?

There are 3 types of lipids (fats) Phospholipids Glycolipids Cholesterol

Proteins Integral (glycoprotein) Peripheral

Made of lipids (fats) with a phosphate head

Lipid portion is 2 fatty acid tails. The tail is hydrophobic: does NOT like water

Phosphate head is hydrophilic: it DOES like water.

phospholipid

Cholesterol embedded in membrane keeps it fluid

The bi-layer is known as the Fluid Mosaic Model, because proteins embedded in the membrane can move

Fluid Mosaic Model

Here is what a phospholipid bi-layer looks like as a sphere

Fluid Mosaic Model

• Materials must move in and out of the cell through the plasma membrane.

• Some materials move between the phospholipids.

• Some materials move through the proteins.

Some proteins span membrane and determine which molecules can enter or leave. These are transport proteins.

Other proteins on the surface act as receptors

1) Channel Proteins2) Carrier Proteins3) Enzymatic Proteins4) Receptor Proteins5) Cell Recognition

Proteins

Have channels that allow molecules to move from an area of high concentration to an area of low concentration. NO energy is used

Carrier Proteins – combine with a molecule to help it move across the membrane

– Carry out metabolic reactions

Receptor Proteins– Have a binding site for a specific molecule.

Marker Proteins–extend across the cell membrane and serve to identify the cell. The immune system uses these proteins to tell friendly cells from foreign invaders. They are as unique as fingerprints.

They play an important role in organ transplants. If the marker proteins on a transplanted organ are different from those of the original organ the body will reject it as a foreign invader.

Selectively Permeable

What is the function of the cell/plasma membrane?

What is the membrane made of?

The membrane is said to be ________________

What is the name of the model?

How can molecules enter the cell?

http://www.wisc-online.com/objects/ViewObject.aspx?ID=ap1101

Cell membranes are constructed mainly of: A. lipid bi-layers B . Protein pumps C. carbohydrate gates D. chloroplast