Cell Membrane Structure

Question 1

What is the plasma membrane made out of

Answer 1

It is made up of a double layer of phospholipids, with proteins embedded in it

Question 2

The membrane is “selectively permeable”, what exactly does this mean

Answer 2

This means that it only lets certain materials in and out of the cell

Question 3

What are the functions of the membrane

Answer 3

-transports materials that it needs into the cell (oxygen, vitamins, water)

-transports manufactured products (proteins) and wastes out of the cell (urea, carbon dioxide)

-keeps unwanted substances out (virus)

-keeps important sciences from leaving (cytoplasm)

Question 4

Why is it important for the cell membrane to be selectively permeable

Answer 4

Conditions inside the cell must remain nearly constant for a cell to function properly. The process of maintainng a constant internal state despite changing external/internal conditions is called HOMEOSTASIS. The cell membrane accomplishes this by controlling what enters/leaves a cell

Question 5

What is every cell bathed in

Answer 5

A thin layer of extracellular fluid, which contains water and a variety of dissolved materials

Question 6

What is the structure of phospholipids

Answer 6

-arranged in two layers

-provides the overall structure for the cell membrane

Question 7

What is the function(s) of phospholipids

Answer 7

-acts as a barrier between the cell and its surroundings

-holds the other components of the cell membrane

Question 8

What is the structure of proteins

Answer 8

-most are embedded inside the phospholipid bi-layer

-some are attached to the inside or outside surface of the phospholipid bi-layer

Question 9

What is the function(s) of proteins

Answer 9

-some transport specific substances across the membrane

-some are enzymes and control chemical reactions

-some transmit signals from other cells or elsewhere in the body

Question 10

What is the structure of cholesterols

Answer 10

Embedded in the phospholipid bi-layer

Question 11

What is the function(s) of cholesterols

Answer 11

-helps keep fluidity of the membrane consistent

-reduces fluidity of membrane at high temperatures

-increases fluidity of membrane at low temperatures

Question 12

What is the structure of carbohydrates

Answer 12

Attached to proteins or phospholipids and protrude outside the cell

Question 13

What is the function of carbohydrates

Answer 13

-allows other cells to “recognize” the cell as belonging to the organism and not an intruder