B1.1 Carbohydrates and lipidsIB Biology SL: Flashcards

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How many covalent bonds can a carbon atom form?

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How many covalent bonds can a carbon atom form?: Up to four, as single bonds or a combination of single and double bonds.
What happens in a condensation reaction?: Two monomers are joined and a water molecule is released.
What happens in hydrolysis?: Water is split to provide —H and —OH groups, breaking a polymer into monomers.
Pentose vs hexose?: Pentose: 5-carbon sugar (e.g. ribose). Hexose: 6-carbon sugar (e.g. glucose).
Which properties of glucose suit it to its role?: Soluble, transportable, chemically stable and yields energy when oxidised.
Why are starch and glycogen good energy stores?: Compact (coiled, branched), insoluble (large), and glucose is easily added or removed.
How does cellulose's structure suit its function?: β-glucose with alternating orientation gives straight chains, bundled and cross-linked by hydrogen bonds into strong fibres.
What are ABO antigens?: Glycoproteins on red blood cells used in cell–cell recognition.
What defines a lipid?: Dissolves in non-polar solvents but only sparingly in water: fats, oils, waxes, steroids.
Triglyceride vs phospholipid?: Triglyceride: glycerol + 3 fatty acids. Phospholipid: glycerol + 2 fatty acids + phosphate.
How do C=C double bonds affect melting point?: More cis double bonds, more kinks, looser packing, lower melting point.
Why are triglycerides good for long-term storage?: High energy per gram, stored without water, insoluble (no osmotic effect), chemically stable.
What does amphipathic mean?: Having a hydrophilic region and a hydrophobic region, as in phospholipids.
Why can oestradiol and testosterone cross membranes?: They are non-polar steroids, so they dissolve through the phospholipid bilayer.