Cell Biology standard 1a

Students know cells are enclosed within semipermeable membranes that regulate their interaction with their surroundings.

Unit 2: Cells

Chapter 7-3

Learning Goals:Learning Goals:•1. Describe the job/function of the cell membrane

•2. Explain what semi-permeable means.

•3. Describe the structure of the cell membrane.

•4. Describe the 3 types of movement across the cell membrane. Include whether energy is required and which direction the molecules move.

Cell Membranes surround ALL cells!

It controls what enters/leaves the cell

SEMIPERMEABLE – means it allows some things through but not others

Made up of a Phospholipid bilayer

Polar heads “love” water (hydrophilic) Nonpolar tails “fear” water (hydrophobic)

“Fluid mosaic model” – describes the structure of the cell membrane.

Proteins float around in the membrane like icebergs in the ocean

A. Surrounds all cells B. Controls what enters and leaves the cell C. Surrounds the nucleus D. Is a phospholipid bilayer

Which of the following is NOT Which of the following is NOT true about the cell true about the cell membrane:membrane:

A. All things can pass through B. Some things are let in or out but not

everything C. Everything is blocked D. Only small molecules may pass through

The cell membrane is The cell membrane is semipermeable. This means:semipermeable. This means:

Keeps things in or out

Molecules can enter/leave the cell 3 ways1. Diffusion2. Carrier-Facilitated (“helped”) diffusion3. Active transport

No energy required

Molecules move from area of high concentration to area of low concentration

Concentration = # of molecules in an area

Diffusion of water is called “osmosis”

ATP

X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X

X X X X X X X X X X X X X X X X X X X

No energy required

Molecules “helped” across by proteins from high to low concentration

ATP

Energy required!◦ ATP – the “battery” of the cell◦ Breaking a bond in ATP releases energy◦ Can “pump” molecules from low to high

concentration building them up in the cell

ATP

The diffusion of water is The diffusion of water is called:called: A Osmosis B. Transfusion C. Water transport D. Active transport

A. From low to high’ no energy B. From low to high; needs energy C. From high to low; no energy D. From high to low; needs energy

In diffusion molecules In diffusion molecules move:move:

A. From low to high’ no energy B. From low to high; needs energy C. From high to low with the help of a

protein; no energy D. From high to low; needs energy

In carrier facilitated diffusion In carrier facilitated diffusion molecules move:molecules move:

A. From low to high’ no energy B. From low to high; needs energy C. From high to low; no energy D. From high to low; needs energy

In active transport molecules In active transport molecules move:move:

Learning Goals:Learning Goals:•1. Describe the job/function of the cell membrane

•2. Explain what semi-permeable means.

•3. Draw and label the structure of the cell membrane.

•4. Describe the 3 types of movement across the cell membrane. Include whether energy is required and which direction the molecules move.