cell membrane and transport knowt

2 characteristics that cell membranes have

Thin- easily allow for movements of materials in/out of cell

Flexible- to allow for ease of movemnt

Name two Functions of the cell membrane

Regulates what enters/exits the cell

Provides protection and support for cell

Primary membrane composition

Proteins and phospholipids

Secondary membrane composition

Carbohydrates and cholesterol

Is hydrophilic attracted to water or repelled by water

Attracted

Is hydrophobic attracted to water or repelled by water

Repelled

Is hydrophilic the outer or inner portion of the cell membrane

Outer portion

Is hydrophobic the outer or inner portion of the cell membrane

Inner portion

What is selective permeability

Only certain molecules can cross. Nonpolar molecules can cross with ease, while polar molecules and ions do not. (They require assistance from transport proteins)

What are 4 functions of a membrane protein

• carry out some of the cells chemical reactions

• Aid in the transport of specific molecules or ions

• Send and receive chemical signals

• Recognize neighboring cells

What is concentration gradient

Difference in concentration of a substance between two areas (goes from high to low concentration)

What is diffusion

Movement of particles down a concentration gradient from an area of high concentration to low concentration

When does equilibrium occur

When the solution has become evenly distributed throughout the solution

2 characteristics of diffusion

1. Does not require energy= passive transport

2. Depends on random movement of particles

Importance of diffusion

Allows cells to

• gain useful substances they require to obtain energy and grow

• Get rid of waste products

What is osmosis

Diffusion of water across through a selectively permeable membrane

What is the difference between osmosis and diffusion?

Diffusion involves the movement of many types of molecules and substances

Osmosis refers to specifically to the movement of water

What is tonicity

Describes the ability of a surrounding solution to cause a cell to gain or lose water

Hypertonic

More concentrated

High solute concentration

Lower water concentration

Hypotonic

Less concentrated

Lower solute concentration

Higher water concentration

Isotonic

Equal concentration compared to cell

Osmosis is how plant cells take up water through their____

Roots

What is turgor pressure

The force within the cell that pushes the plasma membrane against the cell wall

Negative feedback

Return to homeostasis- when a system responds to change by returning to its original state

Example of negative feedback

If you get to hot you sweat to cool down

If your cold you shovel to warm up

Positive feedback

Moving away from homeostasis

Example of positive feedback

Childbirth, blood clotting, fruit ripening

What is a cell membrane mainly composed of?

Lipids and proteins

The framework of a cell membrane consists of…

Double layer of phospholipid

What are the only type of molecules that can pass through the phospholipid bilayer?

Only lipids like oxygen, carbon dioxide and steroids because the cell membrane is mostly lipid

How do water soluble substances (like sugars and amino acids) get into and out of the cell?

They need help by various portions

Function of fibrous proteins

Serve as receptors for the cell

Function of globular pore proteins

To allow lipid insoluble water molecules to pass through

Function of channel proteins

Transport ions for the cell

Function of (globular) glycoproteins

Be enzymes or associations that identify the cell

Function of cholesterol

Stabilizes the membrane