Membranes & transport - lipid bilayers

Question 1

What forms the basic structure of cell membranes?

Answer 1

Phospholipids

Question 2

What type of structure do phospholipids form in cell membranes?

Answer 2

Phospholipid bilayers

Question 3

What are the two components of a phospholipid?

Answer 3

• Hydrophilic phosphate head
• Two hydrophobic hydrocarbon (fatty acid) tails

Question 4

What term describes molecules that have both hydrophilic and hydrophobic parts?

Answer 4

Amphipathic

Question 5

Is the phosphate head of a phospholipid polar or nonpolar?

Answer 5

Polar

Question 6

Is the fatty acid tail of a phospholipid polar or nonpolar?

Answer 6

Nonpolar

Question 7

What happens to phospholipids when placed in water?

Answer 7

Hydrophilic phosphate heads orient towards water, hydrophobic tails orient away

Question 8

What forms when there is a sufficient concentration of phospholipids?

Answer 8

Phospholipid bilayers

Question 9

What are the two regions of a phospholipid bilayer?

Answer 9

• Hydrophobic core
• Hydrophilic outer layer

Question 10

What attracts the hydrophobic regions of the phospholipid bilayer?

Answer 10

Each other

Question 11

What attracts the hydrophilic regions of the phospholipid bilayer?

Answer 11

Water in the cytoplasm or extracellular fluid

Question 12

What property allows the phospholipid bilayer to form a barrier?

Answer 12

Hydrophobic and hydrophilic properties

Question 13

Can large molecules pass through the phospholipid bilayer?

Answer 13

No

Question 14

Why can’t polar molecules and ions pass through the hydrophobic tails of the phospholipid structure?

Answer 14

They do not interact with the hydrophobic fatty acid tails

Question 15

What is the function of the phospholipid bilayer in relation to molecule passage?

Answer 15

Controls which molecules pass through and out of the cell