Phospholipids and Proteins

Question 1

What are phospholipids?

Answer 1

A type of hydrophobic and non-polar lipid, made of two fatty acid chain ‘tails’ attached to a hydrophilic and polar phosphate group ‘head’.

Question 2

What is the shape that the phospholipids form due to?

Answer 2

Their polar nature and the way they interact with water.

Question 3

Which two things will the phospholipids form?

Answer 3

A bilayer or a micelle.

Question 4

What does the phospholipids act as in a membrane?

Answer 4

A barrier to most substances, which help control what enters/exits the cell.

Question 5

What type of molecule will diffuse faster and easier across a membrane?

Answer 5

The smaller and less polar

Question 6

Examples of molecules which will diffuse rapidly.

Answer 6

Oxygen and Carbon Dioxide. (non polar and small)

Question 7

Examples of molecules which will diffuse slowly.

Answer 7

Water and Urea. ( polar and small)

Question 8

Examples of molecules which are unlikely to diffuse.

Answer 8

Charged particles (ions) even if they are small.

Question 9

What are the two types of proteins?

Answer 9

Intrinsic and Extrinsic.

Question 10

Where are the intrinsic proteins found?

Answer 10

Span the whole width of the membrane.

Question 11

Where are the extrinsic proteins found?

Answer 11

Are confined to the inner or outer surface of the membrane.

Question 12

How much space do proteins in membranes make up? And how much?

Answer 12

Make up 45% by mass of cell membrane but can vary from 25% to 75% depending on cell type.

Question 13

Many Intrinsic Proteins are…

Answer 13

Carrier Molecules or Channels.

Question 14

What is the function of the Intrinsic Proteins?

Answer 14

Help transport substances such as ions that cannot diffuse across the membrane but are still vital to a cells functioning.

Question 15

What are other examples of Intrinsic Proteins?

Answer 15

Receptors for Hormones and Neurotransmitters.Enzymes for Catalysing Reactions.

Question 16

What 2 sides can the extrinsic proteins be on?

Answer 16

Extracellular or Cytosolic

Question 17

On the Extracellular side what function do the extrinsic proteins have?

Answer 17

Act as receptors for hormones or neurotransmitters.Involved are cell recognition.

Question 18

What type of proteins are most common as extrinsic proteins?

Answer 18

Glycoproteins.

Question 19

On the Cytosolic side what function do the extrinsic proteins have?

Answer 19

Involved in cell signalling or chemical reaction.

Question 20

What can happen to the extrinsic proteins on the cytosolic side?

Answer 20

They can disassociate from the membrane and move into the cytoplasm.

Question 21

What are Glycolipids?

Answer 21

Lipids with attached carbohydrate chains.

Question 22

What are Glycolipids also known as?

Answer 22

Cell markers or antigens.

Question 23

In which two ways can the glycolipids be recognised by the cells of the immune system?

Answer 23

As self of the organism.Non-self of cells belonging to another organism.

Question 24

What are Glycoproteins?

Answer 24

Proteins embedded into the cell surface membrane with attached carbohydrate chains of various lengths and shapes.

Question 25

What role does Glycoproteins play?

Answer 25

In cell adhesion and as receptors.

Question 26

What is cholesterol and its displayed formula?

Answer 26

A type of lipid-C27H46O

Question 27

What does cholesterol have an important role in?

Answer 27

Controlling membrane fluidity.-More cholesterol, less fluids and less permeable.

Question 28

What is another role cholesterol has but specifically within the body?

Answer 28

Keeping membranes stable at normal body temperature. Cells would burst open otherwise.