UWCSEA IB Biology 2025 - B1.1 Carbohydrates and Lipids

Carbon

The fundamental element forming the basis of all life, known for its ability to create multiple bonds, allowing diverse organic molecule formation.

Monomers

Individual units that combine to create larger molecules.

Polymers

Long chains composed of repeating monomer units.

Condensation Reactions

Chemical processes where monomers combine, producing polymers while removing water.

Hydrolysis Reactions

Processes where polymers are broken down through the addition of water, disrupting bonds and forming monomers.

Monosaccharides

Single sugars, like glucose, that can form 5- or 6-carbon ring structures.

Starch

A polysaccharide used by plant cells to store glucose for energy. Typically consists of alpha glucose units forming branched structures.

Glycogen

A polysaccharide used by animal cells to store glucose for energy. Typically consists of alpha glucose units forming branched structures.

Cellulose

A polysaccharide composed of beta glucose units that provide strength to plant cell walls, preventing bursting.

Glycoproteins

Proteins with sugar chains at their ends, often acting as receptors on cell surfaces, facilitating cell recognition and binding.

Lipids

Organic compounds that do not dissolve in water due to their hydrophobic nature, including fats, oils, waxes, and steroids.

Triglycerides

Molecules formed through condensation of three fatty acids and glycerol, resulting in the removal of water.

Saturated Fats

Fats with only single carbon-carbon bonds, typically solid at room temperature. Used for energy storage in plants and insulation in animals.

Monounsaturated Fats

Fats with one double bond, typically liquid at room temperature. Used for energy storage in plants and insulation in animals.

Polyunsaturated Fats

Fats with two or more double bonds, typically oils at room temperature. Used for energy storage in plants and insulation in animals.

Phospholipids

Molecules with hydrophobic tails and hydrophilic heads that self-arrange into lipid bilayers, forming cell membranes.

Non-polar Substances

Molecules that can pass directly through the phospholipid bilayer of cell membranes due to their similar non-polar nature with the membrane. Examples include steroid hormones like oestradiol and testosterone.