Topic 2-Biomolecules

• What percentage of the human body is made up of water?


  60-70%
• Why is water considered the most critical molecule for life on Earth?


  Because it is a polar molecule and can form hydrogen bonds
• What are the three states of matter that water can exist in?


  Solid, liquid, and gas
• What causes the three states of matter in water?

  The presence of hydrogen bonding intermolecular forces
• How does hydrogen bonding affect the structure of ice compared to liquid water?


  Ice has a highly ordered, less dense crystalline structure
• What property of water allows it to resist temperature changes?


  High specific heat capacity
• What is cohesion in relation to water molecules?


  Cohesion is the tendency of water molecules to stick to one another
• What is surface tension in water?


  It is the capacity of a substance to withstand being ruptured under tension or stress
• What is adhesion in the context of water molecules?


  Adhesion is the attraction between water molecules and other molecules
• How does water move up a glass tube?

  -Water moves up due to the attraction between water molecules and the charged surface of the glass

  -There is attraction between the partial negative charge on the oxygen and the partial positive charge on the hydrogens in the water molecules and the opposing charges on the molecules within the glass.
• Why can many substances dissolve in water?

  Because water is a polar molecule and follows the principle "like dissolves like"
• What role does water play in chemical reactions within cells?


  It allows chemical reactions to occur as dissolved solutes are more reactive
• What is osmosis?


  Osmosis is the movement of water from a region of lower solute concentration to a region of higher solute concentration
• What happens during a hydrolysis reaction?

  •A molecule is split into two by inserting a molecule of water

  • A molecule composed of multiple subunits is split in two: one of the new molecules gains a hydrogen atom, while the other gains a hydroxyl (-OH) group, both of which are donated by water.

  • This is the reverse of a condensation reaction, and it releases a monomer that can be used in building a new polymer
• What is the function of enzymes in biological reactions?

  -Enzymes catalyze reactions, speeding up the breakdown of large molecules

  -Enzymes involved in breaking bonds are often given names that end with –ase As food travels through the digestive system from the moment it hits the saliva – it is being worked over by enzymes like these. The enzymes break down large biological molecules, releasing the smaller building blocks that can be readily absorbed and used by the human body.
• Carbohydrates function

  • Carbohydrates are used primarily as an energy source (glucose and its polymers) in diverse organisms (prokaryotes and eukaryotes)

  • Plants and arthropods also use carbohydrate polymers as structural elements
• What are the different classes of carbohydrates and their functions?

  • Monosaccharides: These are single sugars and exist as different types depending on the number of carbon atoms and their structure
  • Disaccharides: When 2 monosaccharides join in a condensation reaction
  • Polysaccharides: A chain of monosaccharides
• What are the two forms of glucose known as?

  Alpha (α) glucose and beta (β) glucose
• What is glycogen and its function?

  -Animals have this instead of starch. Chains of alpha-glucose formed by condensation reaction. Short chain, highly branched. Insoluble and compact.

  -function- main energy storage in animals
• What is the main energy storage carbohydrate in plants?

  -Chains of α-glucose (amylose + amylopectin) linked by glycosidic bonds formed from condensation reaction

  -Unbranched

  -Amylose -long, unbranched chains of a-glucose. Coiled structure, held by hydrogen bonds. Compact - good for storage.

  Function- Main energy storage in plants
• What is cellulose and its role in plants?

  Long, unbranched chains of beta-glucose formed by condensation reaction.

  Flip every other β-glucose molecule upside down so glycosidic bonds can form

  Structure - straight cellulose chains linked b hydrogen bonds to form microfibrils, which form fibres.

  Structural support + rigidity.

  Prevents influx of H20
• What are the different classes of lipids and their functions?

  • Phospholipids: form cell membranes
  • Steroids: signaling molecules
  • Waxes: protective coatings
  • Fats and oils: energy storage and insulation
• Why do lipids not dissolve in water?


  Because lipids are nonpolar molecules and are hydrophobic
• What is triacylglycerol and how is it formed?


  Triacylglycerol is formed by adding three fatty acid chains to glycerol
• What is the structure of steroids?


  Four fused carbon-containing rings
• What is the most common constituent of cells after water?

  Proteins
• What distinguishes one amino acid from another?


  The R group (side chain)
• What happens to a protein if its shape is changed?


  The function of the protein changes
• What is sickle-cell disease caused by?


  A single amino acid substitution in the protein hemoglobin
• What are nucleic acids primarily used for?


  Information storage and transfer
• What are the three main types of RNA involved in protein synthesis?

  mRNA, rRNA, and tRNA
• What is the structure of DNA primarily used for?


  Information storage
• What is the role of RNA in viruses?


  RNA serves as the primary genetic material for viruses
• Summary of properties of water.

  • An excellent solvent – many substances can dissolve in water

  • A relatively high specific heat capacity

  • A relatively high latent heat of vaporisation

  • Water is less dense when a solid

  • Water has high surface tension and cohesion

  • It acts as a reagent
• CARBON AS AN ESSENTIAL ATOM OF LIFE

  Carbon is unique:

  • It can form covalent bonds with up to four different atoms

  • This allows it to serve as the “backbone” for the macromolecules

  • Each carbon has four electrons in the outer shell

  • It forms four covalent bonds to “fill” the outer shell

  • This allows it to achieve the “octet rule”
• Condensation reactions


  • The synthesis of macromolecules involves the formation of covalent bonds between subunits (monomers) through the removal of a water molecule (H, OH)