CELL MEMBRANE EXAM REVIEW

Terms to know:

Glycolipid- any membrane lipid that is bound to a carbohydrate 

Cholesterol- type of lipid found in the blood plays a role in building cell membrane and produces hormones

facilitated diffusion- the facilitated transport of ions and polar molecules through a membrane via protein complexes 

Hypotonic- the property of a solution that has a lower solute concentrations then another solution 

Isotonic- same 

Hypertonic- the property of a solution that has a high solute concentration than another solution 

Uniport- move 1 molecule in 1 direction, also known as a primary active transport, ex ca

Symport- protein moves 2 different molecules in the same direction 

Antiport- protein moves 2 different molecules in 2 different directions 

Integral protein- a protein that is embedded in the lipid bilayer  

peripheral protein- a protein that on the surface of the membrane 

Endocytosis- proteins and large molecules are brought into the cell, membrane folds inward forming pseudopodia “false feet” eventually they fuse forming a vesicle trapping the molecules, import into cell 

Exocytosis- vesicles move through cell and fuse will cell membrane, vesicles opens and releases molecules to exterior of cell, used for hormones, proteins that need to get into bloodstream, export out of the cell

Pinocytosis- “cell drinking” cell brings in water and dissolved solutes 

Phagocytosis- “cell eating” cell bring in solid molecules (dead cell virus) used by immune system 

1. Be able to label the diagram of the cell membrane.

2. What are the functions of the cell membrane? (7)

Functions of the Cell Membrane:

1. Transport material into cells (glucose, minerals, o2)

2. Transport products and wastes out of (ATP, protein, Co2) 

3. Prevent entry of unwanted matter (toxic)

4. Cell recognition- “name tags” recognize cells as self or foreign 

5. Site of reaction- light absorption, ATP synthesis

6. Communication- between cells, uses hormones, nerve impulses and receptors 

7. Physical connections- connects cell together or to tissue 

3. What is the structure of a phospholipid? How does this account for the formation of  the lipid bilayer?

• 2 fatty acid tails linked to a glycerol backbone with a phosphate group 

• Tails are hydrophobic (non-polar) 

• Heads are hydrophilic (polar) 

4. What is the function of sterols in the membrane?

Sterols- act as a membrane stabilizes

influence membrane fluidity

ex cholesterol

5. What is the function of integral and peripheral proteins?

Integral- span the entire membrane

Peripheral- stuck on outside 

6. What is the function of glycolipids and glycoproteins

   carbs attached to lipids or protiens are embedded in the membrane and act as receptors or name tags to help identify the type of cell as well as provide a site for hormones
   

7. Compare and contrast passive to active transport. How does facilitated diffusion compare to each?

Facilitated diffusion 

• Movement from high to low concentrations 

• Small non-polar molecules (o2, co2) 

• Small polar uncharged molecules (glycerol, water) can move through the membrane 

• NO ions, large molecules or charged molecules 

8. What type of molecules will pass by passive? By active?

Passive Transport:

1. Small Nonpolar Molecules – (e.g., oxygen, carbon dioxide)

2. Small Polar Molecules – (e.g., water, ethanol)

3. Ions (with channels) – (e.g., Na⁺, K⁺ through ion channels)

Active Transport:

1. Large Molecules – (e.g., glucose, amino acids)

2. Ions – (e.g., Na⁺, K⁺ against concentration gradient)

3. Macromolecules – (e.g., proteins, polysaccharides)

9.Use a diagram to explain what happens when a cell is in hypertonic, hypotonic and isotonic conditions.

Hypotonic 

• More solute (NA+) in the cell 

• Water moves into the dilute (balance) 

Concentrations 

• Animal cells- Lyse “burst” 

• Plant cells- turgid 

Hypertonic 

• More solutes outside of cell 

• Water moves out to balance 

• Animal cells- shrivel 

• Plant cells- wilt 

Isotonic 

• When the solute concentration

Inside and outside the cell is balanced

• Water continues to move in and out

At the equal rate 

10. Explain specifically how temperature changes, pH changes and organic solvents work to destroy the cell membrane. 

Unsaturated- have kinks or bends which make membrane more fluid 

Colder temp- molecules pack together closely and make it more viscous “gel like”

More unsaturated- lower its gelling temp

High temp- help keep phospholipids together

11. uniport = moves 1 molecule in 1 direction (also known as primary active transport)

symport= protien moves 2 different molecules in the same direction

antiport= protien moves 2 different molecules in 2 different directions