Biological Molecules (Biology)

• What are the elements present in carbohydrates?

  Oxygen, hydrogen and carbon ONLY
• What are the elements present in proteins?

  Carbon, hydrogen, oxygen and nitrogen
• What are the elements present in lipids?

  Carbon, hydrogen and oxygen
• Structure of Carbohydrates


  Large molecules made from smaller starch and glycogen from simple sugars
• What are monosaccharides?


  Simple sugars
• Name 3 monosaccharides


  Glucose, fructose, galactose
• What is the chemical formula for glucose?

  C6H12O6
• What are disaccharides?


  Two monosaccharides joined together
• Name 3 disaccharides


  Sucrose, lactose, maltose
• What are polysaccharides?


  Large macromolecules formed from monosaccharides
• Name 3 polysaccharides


  Starch, glycogen, cellulose
• What is the function of starch?

  Energy storage in plants
• What is the function of glycogen?

  Energy storage in animals and humans
• What is the function of cellulose?


  Providing structure to plant cell walls
• What is the difference between glycogen and starch?

  Glycogen is stored sugar in animals and starch is stored sugar in plant cells
• Structure of Proteins


  Large molecules made up from amino acids
• What are amino acids?

  Monomers of proteins
• Structure of Lipids


  They are long fatty acids and glycerol attached together to make long chains
• What are monomers?


  Smaller units from which larger molecules are made
• What are polymers?


  Long chains of monomers
• Chemical test for Glucose

  - Add some Benedict's solution to the substance inside the test tube

  - Then place the test tube into a water bath where it will heat up for five minutes

  - Once you have taken out the test tube, the substance would have changed colour depending on how much glucose it contained

  - Blue = None, Yellow = Trace, Green = Some, Orange = moderate, Brick red = A lot
• Chemical test for Starch

  - Add iodine solution to the substance in the test tube

  - A positive result would be a colour change from Yellow to Blue/Black

  - A negative result would be the colour staying the same
• Functions of Carbohydrates in organisms

  long term energy, structural component, quick energy source
• Functions of Lipids in organisms


  An energy store, an insulation and provides fat to our bodies
• Functions of Proteins in organisms

  structure, growth and repair and enzymes
• Chemical test for protein

  - Add Biuret Reagent to the substance

  - If it turns from blue to purple it is a positive result

  - If it stays the same it contains no protein
• Chemical test for lipids

  - Add ethanol

  - Mix the test tube with the substance in well

  - Add the mixture to water slowly

  - A cloudy white emulation would form if it is positive
• What are metabolic reactions?

  All of the reactions inside an organism
• What do enzymes do in metabolic reactions?

  They speed up the chemical reactions in our bodies
• What do biological catalysts do?


  They speeds up chemical reactions with enzymes
• Enzymes in cold temperatures

  - Move slowly

  - Fewer collisions between the enzyme and substrate

  - Less kinetic energy

  - Change of successful collision is low

  - Rate of reaction is low

  - Active site is complementary to the substrate
• Enzymes in hot temperatures

  - Move very quickly

  - Even more collisions

  - Even more kinetic energy

  - Rate of reaction is low

  - Active site is no longer complementary to the substrate
• Effect of pH on enzyme activity

  All enzymes work best at optimal pH, above and below the optimal pH the rate of reaction decreases. Extreme pH changes can denature the enzyme.
• Denatured enzyme


  An enzyme which no longer functions because its shape has been changed (possibly due to temperature). This decreases the rate of reaction, as the substrate can no longer fit into the active site, so it cannot be broken down
• How to calculate rate of reaction

  (1/time) x 1000 = rate of reaction
• Relationship between time and rate

  time = 1/rate: the shorter the time, the higher the rate
• How to draw an accurate line graph:

  1. Both axis must be linear, and they must use at least half of the graph paper

  2. The independent variable on the X axis and the dependent variable on the Y axis

  3. They both must be labelled with units, the label and unit must be separated with a slash (/)

  4. Points must be plotted accurately

  5. Points are joined with straight lines, with a ruler, no lines before or after the last data points
• How to make an accurate results table:

  First column - The independent variable with units included

  Second & third column (if there are repeats ) - The dependent variable with the units only in the headings

  Forth column (if there are repeats) - Is the average/mean value