Biology chapter 3 sections 4-5

What is the major 'take home message' of 3.5

A cell membrane is in all cells, it is fluid (always in motion), and is made primarily of phospholipids and proteins

Define amphipathic.

A molecule that has both a hydrophilic region and a hydrophobic region.

Name the watery fluid on either side of the cell membrane

Cytoplasm- on the inside of the cell Extracellular fluid- on the outside of the cell

Define hydrophilic.

Having an affinity for water; readily absorbing or dissolving in water. Also can be known as polar.

How do molecules without a charge get into and out of the cell?

Diffusion

Name some other things in the cell membrane.

Glycoprotein- protein with sugar attached Glycolipid- lipid with sugar attached Cholesteral

How is the cholesteral inportant to the phospholipids?

It keeps the two fatty acid tails of the phospholipids from touching each other when it is too hot and drifiting from one another and touching their neighbors when it is too cold

Name the two primary things that make up the cell membrane as well as their function.

Phospholipids- keep water fluid on either side and create structure Proteins- give the molecule its characteristics and allows material in and out of the cell

What four types of proteins are in the cell membrane and what are their functions?

Receptor proteins- Bind to molecules outside the plasma membrane and regulate cell processes Recognition proteins- Mark cells as 'not foreign' so they will not be attacked Transport proteins- Allow very large or very charged molecules into and out of the cell Enzymatic proteins- Help chemical reactions occur more quickly

Define hydrophobic.

Repelling, tending not to combine with, or incapable of dissolving in water. Also can be known as nonpolar.

Why is the fluid mosiac model used to describe how the cell membrane works?

The cell membrane is always moving and is composed of many different things

What parts of the phospholipids are hydrophobic and hydrophilic?

The head is hydrophilic and the two tails are hydrophobic.

How do phospholipids react to water?

The hydrophilic head faces the water, while the hydrophobic tail faces away from the water.

Describe the structure of a phospholipid.

There is one head made up of glycerol linked to phosphorous and there are two carbon-hydrogen chains.

Describe phospholipid bilayer.

Two sets of phospholipids form the inside and outside of the cell membrane. The heads face the inside and outside of the cell membrane which is surrounded by watery fluid and the tails form a middle barrier.

How to very large molecules or molecules with a charge get into the cell?

Using proteins Ex: Aquaporins allow water into a cell