9700 · 2.2
Carbohydrates and lipids flashcards
Revision flashcards for Cambridge 9700 Carbohydrates and lipids (syllabus 2.2). Flip, recall, then mark a real past-paper question.
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What is a condensation reaction?
A chemical reaction where two molecules are joined together to form a larger molecule, with the removal of a small molecule, such as water.
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What is the bond formed between two monosaccharides called?
A glycosidic bond.
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What is the structural difference between α-glucose and β-glucose?
On carbon-1, the hydroxyl (-OH) group points down in α-glucose and points up in β-glucose.
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How does the structure of glycogen relate to its function as an energy store?
It is a large, insoluble molecule that is highly branched. This provides many terminal ends for enzymes to act on, allowing for rapid hydrolysis and release of glucose for respiration.
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Why is cellulose suitable for its structural role in plant cell walls?
It is composed of long, straight, unbranched chains of β-glucose. These chains run parallel and are cross-linked by numerous hydrogen bonds to form strong microfibrils, providing high tensile strength.
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What are the chemical components of a triglyceride?
One molecule of glycerol and three molecules of fatty acids.
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What type of bond is formed between glycerol and a fatty acid, and what is the reaction called?
An ester bond is formed via a condensation reaction.
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Why are phospholipids described as amphipathic, and how does this relate to their function?
They have a hydrophilic (polar) phosphate head and two hydrophobic (non-polar) fatty acid tails. This property causes them to form a bilayer in water, which is the basic structure of cell membranes.