chemistry

• Atom

  Smallest particle of an element
• Element

  Made up of only one kind of atoms
• Molecule

  Electrically neutral group of two or more atoms held together by chemical bonds
• Mixture

  A physical combination of two or more substances
• Solution

  A homogeneous mixture composed of two or more substances
• Chemical bond

  The electric attraction between atoms. The grouping of atoms when bonds are formed are more stable than the component atoms
• Ionic bond

  e.g. Na+ (cation) and Cl- (anion)
• Covalent bond

  Sharing pairs of electrons
• Hydrogen bond

  Weak intermolecular forces
• Energy

  The capacity to do work. Can be kinetic energy or potential energy (chemical energy)
• ATP cycle

  1. ATP -> ADP + Pi + Kinetic energy

  2. ADP + Pi + More potential energy
• Synthesis reaction

  Two or more reactants combine to form a larger product. Energy is used up in forming the chemical bond.
• Decomposition reaction

  A larger reactant is broken down to two or more smaller products. Energy is released from the breaking of the chemical bond.
• Metabolism

  The chemical processes that occur within a living organism in order to maintain life
• Catalyst

  A substance that speeds up a chemical reaction by lowering the activation energy, but is not consumed by the reaction
• Enzyme

  A biological catalyst
• Enzyme catalysis

  1. Reactants move towards the active site on the enzyme

  2. Product is released and enzyme is unchanged and ready to bind with more reactants
• Enzymes in the body

  • They are proteins
  • They control the rate of most chemical reactions in the body
  • They are specific for each kind of chemical reaction, therefore we have many different kinds of enzymes
• Factors that affect enzyme function

  • Temperature
  • pH
  • Concentration of enzyme or substrate
  • Inhibitors e.g. lead, ACE inhibitors
• Molecules that make up the body

  • Carbohydrates e.g. glucose
  • Proteins e.g. hormones
  • Lipids e.g. triglycerides
  • Ions e.g. Na+, Cl-, Ca2+
  • Gases e.g. O2, CO2
  • Water
• Water

  • ~ 50% weight of a young adult woman
  • ~ 60% young adult male
  • Plasma is 92% water
  • Can absorb a large amount of heat and therefore can stabilize our body temperature
  • Most of reactions that happen in the body need to happen in a solution with water
• Carbohydrate synthesis

  1. Glucose + fructose = sucrose

  2. Galactose + glucose = lactose

  3. Glucose + glucose = maltose
• Carbohydrates

  • Made of C, H, O and are the main energy source of the body
• Roles of proteins

  • Regulation e.g. hormones and enzymes
  • Transport e.g. hemaglobin
  • Protection e.g. antibodies
  • Contraction e.g. actin and myosin
  • Structure e.g. keratin & collagen
  • Energy e.g. amino acids can be broken down to give energy (catabolism)
• Amino acids

  The building blocks of proteins
• Properties of lipids

  • Not soluble in water
  • 95% of fats in the body are triglycerides
• Roles of lipids

  • Energy e.g. storage
  • Protection e.g. around organs
  • Insulation e.g. under skin
  • Regulation e.g. steroid hormones
  • Vitamins i.e. Vit. A, D, E and K
  • Structure e.g. cell membrane
• DNA

  Deoxyribonucleic acid, the genetic material of cells that can be duplicated and passed onto offspring
• RNA

  Ribonucleic acid, important in copying DNA to make proteins
• Nucleotides in DNA

  • Adenine
  • Thymine
  • Guanine
  • Cytosine
• Nucleotides in RNA

  • Adenine
  • Uracil
  • Guanine
  • Cytosine
• ATP

  Adenosine triphosphate, 34 kJ/mol