Biological molecules + digestion

• What does a balanced diet contain?

  Proteins, carbohydrates, lipids, vitamins, minerals, and water.
• sources of carbohydrates 


  Bread, cereals, pasta, rice potatoes
• function of carbohydrates 


  source of energy for cells
• sources of protein 


  chicken, fish, red meat, egg, nuts, pulses
• Function of proteins 


  Growth and repair
• sources of lipids


  butter, oil, nuts
• Functions of lipids 


  Insulation and energy storage
• Function of fibre


  Provides roughage for the intestine to push food through it
• sources of fibre 


  whole grains, vegetables
• function of vitamins and minerals

  needed in small quantities to maintain health
• sources of vitamins and minerals

  fruits and vegetables, meats, dairy products
• Function of water


  Needed for chemical reactions to take place in the body
• sources of water


  water, juice, milk, fruits, vegetables
• Vitamin A use


  making a chemical in the retina, also protects the surface of the eye
• effect of vitamin A deficiency

  night blindness
• use of vitamin C in the body

  sticks together cell lining surfaces like the mouth
• effect of vitamin c deficiency

  scurvy : gums bleed
• Use of vitamin D

  helps bones absorb calcium and phosphate
• Effect of vitamin D deficiency

  Rickets, poor teeth
• role of calcium in the body

  making teeth and bones
• role of iron in the body

  part of haemoglobin in RBCS, helps carry oxygen
• Practical: investigate the energy content in a food sample

  
  

  • measure mass of food sample
  • Measure a volume of water, put in boiling tube
  • place boiling tube in a clamp
  • record temp of water
  • spear food on the end of a mounted needle
  • hold in bunsen burner flame
  • place needle with lit food under the test tube
  • continue, relighting if the flame goes out, until food no longer burns
  • stir water gently with thermometer to make sure heat is evenly distributed
  • take final temperature of water
• Energy in Joules per gram formula

  $\frac{\left(final\ temperature\ -\ inital\ temperature\right)\ \times volume\ of\ water\ \times4.2}{mass\ of\ food}$
• what are the chemical elements present in carbohydrates?

  Carbon, hydrogen and oxygen
• what are the chemical elements present in proteins?

  Carbon, hydrogen, oxygen, nitrogen
• what are the chemical elements found in lipids?

  Carbon, hydrogen, and oxygen.
• structure of carbohydrates 


  .

  
• structure of lipids


  one glycerol connected to 3 fatty acids by ester bonds

  
• structure of proteins 


  amino acids

  
• Test for starch 


  add iodine to food sample, if it contains starch the colour change should be yellow-brown to blue-black
• Test for glucose 


  Add Benedict’s solution to a test tube with a sample of food

  Place test tube in a water bath. Temp of water should be 90ºC

  Colour change: blue to orangey red
• test for protein


  grind food with water

  add biurets solution to food sample

  positive result: purple
• test for lipids


  grind food in ethanol

  filter into test tube

  add water

  Positive result -> cloudy white
• What is peristalsis and how does it work?

  Muscle contractions that help push food through the intestine

  circular layer contracts, longitudinal layer relaxes, gut narrows
• Where is Amylase produced?

  Salivary glands and pancreas
• Where is pepsin (protease) formed


  Stomach wall
• where is trypsin formed (protease)

  pancreas
• where is lipase formed

  Pancreas, mouth stomach
• function of mouth


  Produces saliva which contains amylase to digest starch
• function of salivary glands

  Saliva is secreted into the mouth

  Lubricates food for easy swallowing