Phospholipid Membrane

Question 1

What molecules is the plasma membrane of a cell made of?

Answer 1

Phospholipids

Question 2

Can you draw a simple diagram of a phospholipid? Indicate on your diagram which part of the phospholipid is hydrophilic, and which part of it is hydrophobic.

Answer 2

Yes

Question 3

Phospholipids form what bilayer?

Answer 3

Forms lipid bilayer spontaneously in water

Question 4

The ___ of a substance determines how it moves through the cell membrane. (semi-permeable)

Answer 4

Structure (size & polarity)

Question 5

Do smaller or larger molecules move more easily through the cell membrane?

Answer 5

Smaller

Question 6

Do polar or non-polar move more easily through the cell membrane?

Answer 6

Non-polar

Question 7

Is this true? Small hydrophobic molecules move more easily through the cell membrane than large, charged hydrophilic ones.

Answer 7

Yes

Question 8

When water moves across a selectively permeable membrane down its concentration gradient, this is called?

Answer 8

Osmosis

Question 9

What is diffusion?

Answer 9

Substances moving from high concentration to low concentration, then eventually become equally distributed across cell membranes.

Question 10

What are the 3 solution types?

Answer 10

Hypertonic, Hypotonic, Isotonic

Question 11

What is a hypertonic solution? If you put a cell into a hypertonic solution what will happen to the cell?

Answer 11

A hypertonic solution is a higher concentration of solutes than comparison.

The cell will shrink.

Question 12

What is a hypotonic solution? If you put a cell into a hypotonic solution what will happen to the cell?

Answer 12

A hypotonic solution is a lower concentration of solutes than comparison.

The cell will swell.

Question 13

What is an Isotonic solution? If you put a cell into an Isotonic solution what will happen to the cell?

Answer 13

An Isotonic solution is an equal concentration of solutes with comparison.

The cell will stay the same size.

Question 14

What type of protein would you expect to find in the membrane of a kidney cell that must be highly permeable to water?

Answer 14

Aquaporins

Question 15

Can glucose cross the plasma membrane of a cell quickly and easily by simple diffusion? Explain your answer.

Answer 15

Larger uncharged polar molecules such as glucose are unable to cross the plasma membrane by passive diffusion.

Question 16

What are the 2 types of passive transport and define them.

Answer 16

Simple diffusion: substance freely moves across the membrane.
Facilitated diffusion: substance moves across with help.

Question 17

How are simple and facilitated diffusion the same?

Answer 17

Simple diffusion and facilitated diffusion are similar in that both involve movement down the concentration gradient.

Question 18

How are simple and facilitated diffusion different?

Answer 18

The difference is how the substance gets through the cell membrane. In simple diffusion, the substance passes between the phospholipids. In facilitated diffusion, there are specialized membrane channels.

Question 19

What are the 2 types of transport?

Answer 19

Passive & Active

Question 20

What is active transport and its requirements?

Answer 20

When the substance is actively moved across the membrane.

Membrane protien
Energy (ATP)

Question 21

When substances are too big for membrane proteins in Active Transport what happens?

Answer 21

The membrane becomes a transport vessel.
Exocytosis: moving substances outside the cell.
Endocytosis: moving substances inside the cell.

Question 22

Rank these from most to least likely to cross a cell membrane by simple diffusion.

Large non-polar
Small non-polar
Large polar
Small polar
Charged

Answer 22

Most - Least
Small non-polar, Large non-polar, Small polar, Large polar, Charged

Question 23

What’s the difference of hydrophilic and hydrophobic?

Answer 23

Something defined as hydrophilic is actually attracted to water, while something that is hydrophobic resists water.