2.3 Plasma Membrane

Question 1

Technical term

Internal environment of cells

Answer 1

Cytosol

Name given to intracellular fluid

Question 2

What is:

Internal environment of a multicellular organism

Answer 2

The extracellular fluid

I.e. the external environment of the cells e.g. plasma, interstitial fluid

Question 3

List

Properties multicellular organisms regulate:

Answer 3

5 properties

• Concentration of particular salts (ions)
• Temperature
• Concentration of Nutrients, water & nitrogenous waste
• Concentration of CO₂ & H₂O
• Ph value

Question 4

Technical term

Regulating the movement of substances in and out of the cell

Answer 4

Semi-permeable

or selectively permeable

Question 5

What is the structure of the membrane

Answer 5

Mosaic

Proteins and other molecules are embedded in a phospholipid bilayer

Question 6

Character of the cell membrane

Answer 6

Fluid

Protein and phospholipid molecules can move laterally

Question 7

Define

Glycolipid

Answer 7

Lipid with carbohydrate attached

Form tree structures on the surface of the cell

Question 8

Define

Glycoprotein

Answer 8

Protein with carbohydrate attached

Form tree structures on the surface of the cell

Question 9

Technical term

Cells with plasma membrane enclosing cytoplasm and non plasma membranes

Answer 9

Eukaryote

Question 10

List

Character of phospholipid

Answer 10

4 properties

• Hydrophilic Glycerol ‘head’
• Head is polar and contains phosphate
• Two insoluble hydrophobic tails
• Tails are fatty acids

Question 11

List

Two main types of proteins

Answer 11

• Integral Proteins - embedded in the membrane
• Peripheral proteins - attached to the outside of the membrane

Question 12

List

Functions of Integral proteins

Answer 12

2 purposes

• Transport carrier & channel proteins allow substances to pass through
• Receptor bind hormones and other substances

Question 13

List

Functions of Peripheral proteins

Answer 13

2 purposes

• Recognition Attach to carbohydrate molecules that act as markers (antigens)
• AdhesionLink cells together

Question 14

Describe

Carbohydrates & cell membrane

Answer 14

Are involved in cell recognition and adhesion

glycoproteins = linked to proteins
glycolipids = linked to lipids (fats)

Question 15

Why are there cholesterol molecules in cell membranes

Answer 15

Regulate fluidity and gives some stability

Question 16

Why are single cell animals small?

Answer 16

Surface Area to Volume ratio

• Rate of migration is controlled by surface area
• For a given shape, the larger the object to less surface area relative to the volume