B1.1 Carbohydrates and Lipids

Guiding Questions:

  • In what ways do variations in form allow diversity of function in carbohydrates and lipids?

  • How do carbohydrates and lipids compare as energy storage compounds

B1.1.1 Chemical properties of a carbon atom allowing for the formation of diverse compounds upon which life is based

  • all organic compounds contain carbon → carbon can form 4 bonds to different atoms by covalent bonds

  • allows it to be the backbone of life

  • majority of molecules can be categorized into 4 biochemical groups:

    • carbohydrates

      → monosaccharides, polysaccharides

    • lipids

      → triglycerides, phospholipids

    • proteins

      → enzymes, antibodies, peptide hormones

    • nucleic acids

      → nucleotides

B1.1.2 Production of macromolecules by condensation reactions that link monomers to form a polymer

  • macromolecule: made up of smaller molecules called monomers

  • carbohydrate monomer: monosaccharides

  • lipids monomer: glycerol, fatty acids, phosphate groups

  • protein (polypeptide) monomer: amino acids

  • nucleic acids monomer: nucleotides

B1.1.3 Digestion of polymers into monomers by hydrolysis reactions

  • hydrolysis: chemical reactions breaking down macromolecules

  • hydrolysing enzymes: digestive enzymes

B1.1.4 Form and function of monosaccharides

  • ribose: pentose monosaccharide

    • C5H10O5+

ribose

  • glucose: hexose monosaccharide

    • C6H12O6+

    • can be used to make polysaccharides (cellulose and starch being examples)

    • molecular stability: covalent bonds (very strong)

    • high solubility in water: glucose is polar and dissolves in a polar solvent (water)

    • easily transportable: glucose easily circulates in blood and in between cells

glucose

B1.1.5 Polysaccharides as energy storage compounds

  • compact nature of starch in plants and glycogen in animals

    → due to coiling and branching during polymerization

  • glycogen: storage of excess glucose by animals and humans

B1.1.6 Structure of cellulose related its function as a structural polysaccharide in plants

  • alternating orientation of beta-glucose monomers

    → giving straight chains that can be grouped and cross-linked with hydrogen bonds

    reversal of atoms between alpha glucose monomer and beta glucose monomer

B1.1.7 Role of glycoproteins in cell-to-cell recognition

  • lipoprotein: lipid +protein

  • glycolipid: carbohydrate + lipid

  • glycoprotein: carbohydrate + protein

    • glycoproteins MUST be present for cell-to-cell recognition

  • blood proteins called antigens are used to trigger the immune system:

    • people with blood type O → can give blood to others with type O, A, B, or AB

    • people with blood type AB → can receive blood from types AB, A, B, or O

B1.1.8 Hydrophobic properties of lipids

  • lipids → dissolve in non-polar solvents, not water (due to the non-polar covalent bond)

    • examples: fats, oils, waxes, steroids

B1.1.9 Formation of triglycerides and phospholipids by condensation reactions

  • lipids are formed by condensation reactions:

    • 1 glycerol + 3 fatty acids → 1 triglyceride (resulting lipid) + 3 water molecules (output of condensation reaction)

  • phospholipids are formed if an inorganic phosphate replaces one of the fatty acids:

    • 1 glycerol + 2 fatty acids + 1 inorganic phosphate → 1 phospholipid (resulting lipid) + 3 water molecules (output of the condensation reaction)

B1.1.10 Difference between saturated, monosaturated and polysturated fatty acids

  • saturated fatty acids: fatty acids that contain single bonds between the carbons

    • all other carbon bonds are to hydrogens

    • higher melting point (solid at room temperature)

  • monosaturated fatty acids: one double bond between two of the carbons

    • lower melting point (liquid at room temperature)

  • polyunsaturated fatty acids: fatty acids that have more than one double bond

    • lower melting point (liquid at room temperature)

B1.1.11 Triglycerides in adipose tissue for energy storage and thermal insulation

  • properties of triglycerides make them suited for long-term energy functions

  • adipose tissue: composed of cells that store fat in the form of triglycerides

B1.1.12 Formation of phospholipid bilayers as a consequence of the hydrophobic and hydrophilic regions

  • ampipathic molecules: have both hydrophilic and hydrophobic regions

    • example being phospholipids

  • in the phospholipid bilayer → hydrophobic fatty acid tails extend toward each other in order to keep away from the water inside and outside the cell

    • foundation of the plasma membrane

phospholipid bilayer with phospholipids, integral proteins...

B1.1.13 Ability of non-polar steroids to pass through the phospholipid bilayer

  • cholestrol passes through the phospholipid bilayer