Exam 1 Short Answer

Question 1

Facilitated diffusion vs simple diffusion

Answer 1

— similarities:
- both passive= don’t require any energy
— differences:
- facilitated: require some type of carrier protein(proteins are very specific)
-rate of facilitated diffusion plateaus
- simple: as you increase concentration, the rate of simple diffusion goes up

• In simple diffusion, the substance passes between the phospholipids; in facilitated diffusion there are a specialized membrane channels.

Question 2

3 stages of cell to cell communication

Answer 2

• First, reception, whereby the signal molecule binds the receptor.
• Then, signal transduction, which is where the chemical signal results in a series of enzyme activations.
• Finally, the response, which is the resulting cellular responses.

Question 3

what are the enzymes of the phosphorylation cascade?

Answer 3

• protein kinase and protein phosphatase
• Protein kinase adds phosphate groups from ATP (adenosine tri-phosphate) to proteins to phosphorylate them. This process is called phosphorylation.

Question 4

why is water polar?

Answer 4

The unequal sharing of electrons between the atoms and the unsymmetrical shape of the molecule means that a water molecule has two poles - a positive charge on the hydrogen pole (side) and a negative charge on the oxygen pole (side)

Question 5

structure of the plasma membrane

Answer 5

hydrophilic head and hydrophobic tail

• hydrophobic can pass through and dissolve in the plasma membrane
• hydrophilic cannot pass through and doesn’t dissolve