Carbohydrates, Lipids And The Cell Membrane

Question 1

Functions of carbohydrates

Answer 1

• Energy source — provides energy quick through glucose metabolism
• Energy storage — excess glucose is stored as glycogen in animals and a starch in plants
• Structural support — cellulose strengthens plant cell walls, while chitin supports fungal cells and arthropod exoskeletons
• Cell signalling & recognition — glycoproteins and glycolipids in cell membranes aid in cell communication and immune response
• Metabolic intermediates — carbs participates in biochemical pathways such as glycolysis and the Krebs = ATP production

Question 2

What happens if a cell membrane loses its selective permeability ?

Answer 2

Cell would lose control over what enters and exists = nutrient imbalances, toxin accumulation, and potential cell death due to uncontrolled molecular exchange

Question 3

Why do living cells require carbohydrates and lipids ?

Answer 3

Carbohydrates provide a quick energy source and structural support e.g, cellulose in plants.

Lipids serve as a long-term energy storage, structural components of membranes, and precursors to hormones.

Question 4

Simple definition of carbohydrates

Answer 4

Organic molecules composed of carbon, hydrogen and oxygen that are classified as monosaccharides, disaccharides and polysaccharides.

Question 5

Simple definition of lipids

Answer 5

Hydrophobic molecules (macromolecules) composed of carbon, hydrogen and oxygen which are classified as triglycerides, phospholipids and steroids.

Question 6

Functions of lipids

Answer 6

• Storage form of metabolic fuel
• Transport form of metabolic fuel
• Provide structural components of membranes — phospholipids, glycolipids, galactolipids, sphingolipids
• Protective function in bacteria, plants, insects and vertebrates — part of outer coating between the body of the organism and the environment

Question 7

The 4 types of lipids

Answer 7

1. Simple - fatty acids and alcohols
2. Compound (complex) - fatty acids, alcohols and other groups
3. Derived - derived from simple and complex both
4. Miscellaneous - possesses characteristics of lipids

Question 8

Simple lipids - Triacylglycerol (triglyceride)

Answer 8

Examples are fats and oils

• Composed of fatty acids and glycerol
• Storage from of lipids
• Stored in adipose tissue = long term energy reserves

Question 9

Simple lipids - Waxes

Answer 9

• Composed of fatty acids and glycerol
• Waxers = esters made of long-chain alcohol and a fatty acid
• Provides protection, especially to plants in which wax covers the leaves of plants.
• Provides protection to the skin of the ear canal by earwax

Question 10

Simple definition of fatty acids

Answer 10

Long chain hydrocarbons that are a type of carboxylic acid which are the building blocks of fat in the body and food