Core Concepts 1 - Biological Molecules

Cards (53)

  • Name the four key inorganic ions in living organisms.
    Magnesium ions (Mg2+)
    Iron ions (Fe2+)
    Calcium ions (Ca2+)
    Phosphate ions (PO43-)
  • What is the role of Mg2+ in plants?
    Mg2+ is used to produce chlorophyll.
  • What is the role of Fe2+ in animals

    Fe2+ is found in haemoglobin and is involved in the transport of oxygen.
  • What is the role of PO43- in living organisms?
    PO43- is used to produce ADP and ATP
  • What is the role of Ca2+ in living organisms?
    Ca2+ is used to strengthen tissues such as bones and teeth in animals and cell walls in plants.
  • Why is water a polar molecule?
    O is more electronegative than H, so attracts the electron density in the covalent bond more strongly. forms O 𝛿- (slight negative charge) & H 𝛿+ (slight positive charge).
  • Describe hydrogen bonding between water molecules.
    Weak intermolecular forces of attraction form between a lone pair on a δ- O and a δ+ H on an adjacent molecule.
  • What is a metabolite?

    A molecule formed or used in metabolic reactions.
  • Describe the role of water as a metabolite.
    Water is a reactant in photosynthesis and hydrolysis reactions. Water is a product in aerobic respiration and condensation reactions.
  • Why is water's high specific heat capacity important for organisms?
    Water acts as a temperature buffer, enabling endotherms to resist fluctuations in core temperature and to maintain optimum enzyme activity.
  • Why is water's high latent heat of vaporisation important for organisms?
    When water evaporates, it has a cooling effect. This is important in homeostasis; organisms can lose heat through sweating or panting.
  • Why is water an important solvent for organisms?
    Water is a polar universal solvent. It enables chemical reactions to take place within cells, the transport of materials in the plasma and the removal of metabolic waste.
  • Why does water have a high surface tension?
    Due to the ordered arrangement and cohesion of molecules at the surface of water.
  • Why is the high surface tension of water important for organisms?
    - Enables the transport of water and nutrients through plant stems and small blood vessels in the body.
    - Allows small insects to walk on water.
  • What is a monosaccharide?

    - Simple Sugar
    - General formula Cn(H2O)n
  • Give some examples of monosaccharides.
    Glyceraldehyde, Ribose, Deoxyribose, α- and β-glucose, Fructose, Galactose.
  • What is the name of the bond formed when two monosaccharides react?
    Glycosidic Bonds
  • What is a disaccharide?

    - Molecule formed by the condensation of two monosaccharides, forming a glycosidic bond.
    - Formula C12H22O11
  • Give some examples of disaccharides and their monosaccharide constituents.
    - Sucrose (Glucose-Fructose)
    - Maltose (Alpha glucose- Alpha glucose)
    - Lactose (Glucose-Galactose)
  • What is a polysaccharide?
    A polymer of many monosaccharides, formed by condensation reactions.
  • Give some examples of polysaccharides.
    starch, glycogen, cellulose, chitin
  • What is the function of starch?
    energy storage in plants.
  • Describe the structure of starch.
    - Polymer of a-glucose monomers
    - Two forms: Amylose and Amylopectin
    - Amylose: a-1,4 glycosidic bonds, unbranched
    - Amylopectin: a-1,4 and a-1,6 glycosidic bonds, branched
  • What is the function of glycogen?
    Energy storage in animals.
  • How does the structure of glycogen relate to its function?
    It is highly branched enabling the rapid hydrolysis of glucose molecules.
  • Describe the structure and function of cellulose.
    - Linear polysaccharide that is the main component of the cell wall in plants.
    - Consists of many beta-glucose molecules joined by beta- 1,4- glycosidic bonds.
    - Alternate glucose molecules rotated 180 degrees allowing hydrogen bonds between parallel chains, forming myofibrils.
  • Explain how a triglyceride is formed.
    One molecule of glycerol forms ester bonds with three fatty acids through condensation reactions.
  • Relate the structure of triglycerides to their functions.
    ● High energy:mass ratio = high calorific value from oxidation (energy storage).
    ● Insoluble hydrocarbon chain = no effect on water potential of cells & used for waterproofing.
    ● Slow conductor of heat = thermal insulation e.g. adipose tissue.
    Less dense than water = buoyancy of aquatic animals.
  • What is a phospholipid?

    A type of lipid formed by the condensation of one molecule of glycerol, two molecules of fatty acid and a phosphate group.
  • Relate the structure of phospholipids to their functions.
    glycerol backbone attached to two hydrophobic fatty acid tails and one hydrophilic polar phosphate head:
    -forms phospholipid bilayer in water- component of cell membranes.
    -tails splay outwards- waterproofing e.g. skin.
  • What is the difference between saturated and unsaturated fats?
    - Saturated fats have no C=C bonds, and are solid at room temperature due to strong intermolecular forces.
    - Unsaturated fats have one or more C=C bonds, and are liquid at room temperature due to weak intermolecular forces.
  • Differentiate between monounsaturated and polyunsaturated fatty acids.
    - monounsaturated fatty acids contain one C=C bond
    - polyunsaturated fatty acids contain more than one C=C bond
  • What is meant by a low density lipoprotein (LDL)?
    -Combination of triglycerides from saturated fats and protein
    -Blocks receptor sites, reducing cholesterol absorption
    -Known as 'bad' lipoproteins
  • How do LDL's contribute to the risk of cardiovascular disease?
    The high blood cholesterol level caused by LDL's leads to formation of atherosclerosis plaques.
  • Describe the general structure of an amino acid.
    - Amine group (-NH2)
    - Variable side chain (R)
    - Carboxyl group (-COOH)
    - H atom
  • How are polypeptides formed?

    Many amino acid monomers join together in condensation reactions, forming peptide bonds (-CONH-).
  • What is the primary structure of a protein?

    The individual sequence of amino acids in a protein.
  • Describe the secondary structure of a protein.

    The local interactions of the amino acids in the polypeptide chain resulting in alpha-helices or beta-pleated sheets. Hydrogen bonds hold the arrangements in place.
  • Describe the tertiary structure of a protein.
    Folding of a protein to make a three-dimensional structure held in place by various interactions and bonds
    disulphide bonds, ionic bonds, hydrogen bonds, hydrophobic interactions
  • Describe the quaternary structure of a protein.

    - Interactions of more than one polypeptide chain.
    - May involve addition of prosthetic groups, e.g. metal ions or phosphate groups.