Cell organisation

• Cells


  the basic building blocks of life that make up all living organisms
• Tissues 


  A group of similar cells working together to carry out a specific function
• Organ 


  A group of different tissues working together to perform a specific function
• Organ system


  A group of organs working together to carry out a specific function
• Catalyst


  A substance which increases the speed of a reaction without being used up itself
• Enzymes


  Have specific shapes to catalyse reactions

  Lock and key theory- The substrate has to match shapes with the active site to go into it. The substrate with then separate and the active site remains unchanged
• Temperature and pH


  For the enzymes to work at its best, there is an optimum temperature and pH

  If too hot, the bonds of the enzyme will break which changed the shape of the active site so the substrate wont fit anymore (denatured)
• Investigating enzymatic reactions

  1. Add a drop of iodine solution into every well on a spotting tile
  2. Place a Bunsen burner on a heat proof mat
  3. Heat a beaker of water until it reaches 35 degrees
  4. Add amylase solution and buffer solution to a boiling tube. With test tube holders, put the tube in a beaker of water for 5mins
  5. Add starch solution in the boiling tube
  6. Mix and start the stopwatch
  7. Record how long it takes the amylase to break down. When the iodine remains a browny-orange, starch is no longer present.
  8. Repeat the whole experiment
• Rate of reaction


  change/time
• Carbohydrates


  Carbohydrases (e.g. amylase) breaks down starch into simple sugars such as maltose

  Amylase is made in three places: the salivary glands, pancreas, the small intestine
• Protein


  Proteases breaks down proteins into amino acids

  Proteases are made in three places: the stomach, pancreas, the small intestine
• Lipids


  Lipases break down lipids into glycerol and fatty acids

  Lipases are made in two places: the small intestine, pancreas
• Bile


  Produced in the liver, stored in the gall bladder before released in the small intestine

  Bile neutralises the acid and makes the conditions alkaline (the small intestine works best in alkaline conditions)

  It also emulsifies fats and breaks fat into tiny droplets (gives it a bigger surface area)- makes digestion faster
• Benedicts test for sugars

  1. Prepare a food sample and a water bath (75 degrees)
  2. Add the food sample into a test tube
  3. Add benedics solution to the test tube and put it in a water bath for 5 mins
  4. If it turns brick red from blue, sugars are present
• Iodine test for starch

  1. Add prepared food sample to a test tube
  2. Add a few drops of iodine solution and gently shake
  3. If it turns black or blue-black from a browny-orange then starch is present
• Biuret test for proteins

  1. Add a prepared food sample to a test tube
  2. Add biuret solution to the test tube and mix by gently shaking it
  3. If it turns purple from blue, proteins are present
• Sudan III test for fats

  1. Add a prepared food sample into a test tube
  2. Add some Sudan III solution to the test tube
  3. If lipids are present, there will be a red layer at the top of the test tube
• The lungs 


  The air you breath goes through the trachea which splits into two tubes called bronchi. This then splits into smaller tubes called bronchioles

  It then ends with the alveoli
• Alveoli


  Surrounded by a network of blood capillaries

  Blood contains lots of carbon dioxide and very little oxygen. It diffuses outside of the alveolus to be breathed out.

  When blood reached body cells oxygen is released from red blood cells and diffuses into body cells.
• Breathing rate 


  Breaths per minute= number of breaths/number of minutes
• The right ventricle


  Pumps deoxygenated blood to the lungs to take in oxygen. It then returns to the heart
• The left ventricle


  Pumps oxygenated blood to all other organs of the body. It gives up the oxygen body cells so deoxygenated blood returns to the heart to be pumped to the lungs again
• Valves


  Makes sure blood flows in the right direction
• How the heart uses the four chambers:

  1. Blood flows into the atria from the vena cava and pulmonary vein.
  2. The atria contracts, pushing blood into the ventricles
  3. The ventricles contract, forcing blood into the pulmonary artery and the aorta, and out of the heart
  4. Blood then flows to organs through arteries and returns through veins
  5. Atria fills again and the cycle repeats
• Pacemaker


  A pacemaker produces small electrical impulses which spreads to surrounding muscle cells, causing them to contract
• Artificial pacemaker


  Controls the heartbeat if the natural pacemaker doesn't work properly. It produces electrical currents to keep the heart beating regularly
• Arteries


  Carry blood away from the heart

  Walls are strong and elastic to contend to the high pressure

  The walls are thick compared to the size of the hole in the middle (the lumen)

  Contain thick layers of muscle to make them strong and elastic fibres to stretch and spring back
• Veins 


  Carry blood to the heart

  Blood is at a lower pressure so walls aren't as thick as artery walls.

  Have a bigger lumen to help blood flow

  Have valves to keep blood flowing in the right direction
• Capillaries


  Involved in the exchange of materials at the tissues

  Carry blood close to every cell to exchange substances with them

  Have permeable walls for substances to diffuse in and out

  Only one cell thick to increase the rate of diffusion by decreasing the distance over which it occurs.

  Supply food and oxygen and take away waste like carbon dioxide
• White blood cells


  Engulf microorganisms in a process called phagocytosis

  Produce antibodies to fight microorganisms

  Produce antitoxins to neutralise any toxins produced by microorganisms

  They do have a nucleus
• Red blood cells

  Have biconcave disc shape which gives it a big surface area for absorbing oxygen

  Dont have a nucleus- more room to absorb oxygen

  Contain red pigment, haemoglobin which binds to oxygen.

  In body cells, the oxyhaemoglobin splits up to release oxygen
• Platelets


  Help the blood clot- stops blood pouring out and stops microorganisms getting in

  Small fragment of cells with no nucleus.

  Lack of platelets leads to excessive bleeding and bruising
• Plasma


  Carries red/white blood cells, platelets, nutrients (glucose and amino acids), carbon dioxide, urea, hormones, proteins and antibodies/antitoxins
• Stents


  Keep arteries open so blood can pass through to heart muscles. This keeps the heart beating.

  Lower the risk of heart attacks in people with coronary heart disease

  Effective for a long time and recovery time is quick

  Risks of surgery and blood clots near the stent
• Statins 


  Reduce cholesterol in the blood

  Statins are drugs to reduce 'bad' cholesterol in the bloodstream. Slows down the rate of fatty deposits forming

  Advantages: reduces the risk of strokes, heart attacks and coronary heart disease

  Disadvantages: Long term drug that are taken regularly. There's a risk someone could forget to take them, negative side effects and effect isn't instant.
• Artificial hearts


  Pump blood for a person whose heart has failed

  Usually only a temporary fix

  Advantage: less likely to be rejected

  Disadvantage: surgery may lead to bleeding and infection, electrical motor could fail, blood clots could form and lead to strokes
• Faulty heart valves


  Heart valves can be damaged or weakened by heart attacks, infection or old age

  May cause valve tissue to stiffen so it wont open properly. It can also become leaky so blood flows in both directions and doesn't circulate as effectively

  Replacing a faulty valve is much less drastic than a heart transplant but there can still be problems with blood clots.
• Artificial blood 


  Used as a blood substitute to replace lost volume of blood. It is safe and can keep people alive despite losing 2/3 red blood cells.
• Communicable diseases


  A disease that spreads from person to person or animals to people
• Non communicable diseases 


  Cant spread between people or animals and people.

  Generally last a long time and slowly get worse