B1.1 Carbohydrates and lipids Flashcards
B1.1.1 - Chemical properties of a carbon
atom allowing for the formation of diverse compounds upon whic life is based
Forms stable molecules through up to 4 strong covalent bonds, allowing complex structures.
B1.1.2 - Production of macromolecules by
condensation reactions - (CR)
CR - The chemical process that links another monomer onto the end of the polymer.
Two molecules link together, releasing a smaller molecule. For polysaccharides, polypeptides and nucleic acids, it is water.
B1.1.2 - Production of macromolecules by
condensation reactions - glucose
Glucose molecules are linked up with glycosidic bonds, C–O–C linkages.
The -OH on C1 of a glucose links to -OH on C4 at the end of the growing chain (1→4).
To branch, C1 of a glucose is linked to a C6.
B1.1.3 - Digestion of polymers into monomers by hydrolysis reactions
Uses a molecule of water to break a disaccharide into its two monosaccharides.
B1.1.4 - Form and function of monosaccharides - structure
3-7 carbons.
Pent. + hex. = 1 oxygen, 5-6 carbon in a ring.
B1.1.4 - Form and function of monosaccharides - properties and uses of glucose
Glucose is soluble and a relatively small,
so it is easily transported.
Glucose yields energy when it is oxidized. It can be used as a substrate for respiration.
B1.1.4 - Form and function of monosaccharides - glucose anomers
Beta glucose = -OH group attached above the ring.
Alpha glucose = -OH group linked below the ring.
B1.1.5 - Polysaccharides as energy storage
compounds
Starch (plants) and glycogen (animals) are used as energy stores. Both are composed of α-glucose, which can be used a substrate in aerobic and anaerobic cell respiration.
B1.1.5 - Polysaccharides as energy storage
compounds - starch
Amylose is an unbranched chain of α-glucose linked by 1→4 glycosidic
bonds. Bónd angles make the chain helical.
Amylopectin has some 1→6 glycosidic bonds making the molecule branched.
B1.1.5 - Polysaccharides as energy storage
compounds - glucose
Structure: α-glucose molecules linked by 1→4 glycosidic bonds, with 1→6 branching. It is more branched than amylopectin.
Large size reduces solubility, minimizing its impact on osmotic concentration. Branched structure ensures compactness despite mass. These things make it ideal for storing glucose.
B1.1.6 - Structure of cellulose related to its function as a structural polysaccharide in plants - structure
Cellulose is a polymer of β-glucose. All the links in cellulose are 1→4 glycosidic bonds .
To allow a condensation reaction to occur, each β-glucose added to the chain has to be inverted in relation to the previous one.
B1.1.6 - Structure of cellulose related to its function as a structural polysaccharide in plants - structure benefit
Regularly spaced -OH groups enable lots of H-bonding, forming strong microfibrils that make up cell walls. Their high tensile strength, due to covalent bonds, many molecules, and cross-links, prevents cells bursting under high osmotic pressure.
B1.1.8 - Hydrophobic properties of lipids
Lipids dissolve in non-polar solvents and are only sparingly soluble in aqueous
solvents.
B1.1.8 - Hydrophobic properties of lipids - oils and fats
Oils: melting point below 20°C, solidify at low temperatures.
Fats: melting point between 20-37°C, solid at room temp and liquid at body temp.
B1.1.9 - Formation of triglycerides by condensation reactions
Combining three fatty acids with one glycerol in a condensation reaction.
Linkage = ester bond.
The reaction is between the –COOH group on a fatty acid and an -OH on the glycerol.
The reaction removes hydrophilic groups, making triglycerides hydrophobic.
B1.1.9 - Formation of phospholipids by condensation reactions
Two fatty acids linked to glycerol, and a phosphate group.
Phosphate = hydrophilic, so phospholipids are part hydrophilic and part hydrophobic.
B1.1.10 - Cis-fatty acids
Have hydrogen atoms on the same side of the double-bonded carbon atoms.
This causes a kink in the hydrocarbon chain, making the triglyceride less compact, resulting in a low melting point (liquid room temp - oils).
B1.1.10 - Trans-fatty acids
Have hydrogen atoms on opposite sides of the double bond, resulting in straight chains and a higher melting point (solid room temp).
