B3 Organisation and the digestive system Flashcards
Hierarchy of living organisms
cells -> tissues -> organs -> organ systems -> organisms
What are carbohydrates
composed of long chains of simple sugars
What are the three types of carbohydrates
Starches, sugars and fibres
What are the uses of starch and sugars
They give us energy
What do fibres do
They prevent constipation
What are proteins
composed of chains of amino acids
Why do we need proteins
Growth
to repair the body
Why do we need lipids
Energy
Insulation to keep us warm
What are fats
composed of 3 fatty acids & 1 glycerol molecule
What is the test for starchs
Iodine solution
What is the sighs of positive result of starch’s
Orange colour goes blue/black colour
What is the test for reducing sugars
Benedict’s solution
What is the next step to test for reducing sugars
Heat gently for 10 min
What is the sighs of positive result of reducing sugars
Blue colour goes brick-red colour
What is the test for proteins
Biuret A and Biuret B
What is the next step to test for proteins
Shake the test tube gently
What is the sighs of positive result of proteins
Blue colour goes violet colour
What is the test for lipids
Few drops of water and a few drops of ethanol
What is the sighs of positive result of Lipids
White precipitate layer forms
How those enzymes work
1) Enzymes are proteins. They speed up the rate of chemical reactions.
2) They have a specific shape called the active site
3)The active site is complementary to the shape of the substrate molecule. Like a ‘lock and
key’.
4)There are random collisions between the enzyme and the substrate molecule, when the
substrate enters the active site an enzyme – substrate complex is formed.
- Bonds are broken
- Produce are released.
- Enzyme can then be reused.
How does high temperatures affect enzymes
both the enzyme and substrate molecules have more kinetic energy, therefore there are more frequent collisions, more enzyme substrate complexes are formed and more products are released. Over 40°C the enzyme starts to become denatured and no longer functions.
How does pH affect enzymes
each enzyme has an optimum pH. They only work within a narrow range of pH. Higher/lower pHs cause the enzyme to become denatured.
That is Bile
a green alkaline liquid produced by the liver and stored in the gallbladder. It neutralises stomach acid and emulsifies fats
What are the digestive enzymes
Carbohydrase (amylase) enzymes
Protease enzymes
Lipase enzymes
What are the production sites of protease, lipase and carbohydrate enzymes
The small intestine
Pancreas
Where does protease enzymes work
Stomach
small intestine
Where does lipase enzymes work
Small intestine
Where does carbohydrates enzymes work
Mouth
small intestine
Where is food absorbed into the bloodstream
small intestine
Where is water reabsorbed back into the bloodstream
large intestine
