Digestive system

test for lipids

• ethanol + water

• Positive = cloudy

• negative = colourless

Protein test

• Biuret solution

• positive = purple

• negative = no change (stays blue)

simple sugar test

• benedict’s reagent + heat to 85 degrees

• positive = green, yellow, red

• negative = no change (blue)

starch test

• iodine solution

• positive - blue/black

• negative - orange

what is metabolism?

sum of all chemical reactions in a cell/body

what are some metabolic reactions in the liver?

• detoxifying alcohol

• passing waste into urine

• breaking down old blood cells + storing iron

examples of metabolic reactions

• amino acids → protein

• glycerol + 3 fatty acids → lipid

• glucose → starch, glycogen, cellulose

• respiration

• photosynthesis

What does amylase do?

Starch → glucose

what does protease do?

protein → amino acid

what does lipase do?

lipid → glycerol + 3 fatty acid

where is lipase produced, where is it used?

Produced - small intestine + pancreas

Used - small intestine

where is protease produced, where is it used?

Produced - stomach, pancreas, small intestine

Used - stomach, small intestine

where is amylase produced, where is it used?

produced - salivary glands, pancreas

Used - mouth, small intestine

What is the definition of an enzyme

Biological catalyst (protein) that speeds up chemical reactions. can be re-used

what is denaturing

if temp, ph etc is too far away from optimum, amino acid chain unravels. active sight is destroyed and no longer complimentary to the substrate

11 steps of the digestive system

1. mouth

2. salivary glands

3. oesophagus

4. stomach

5. liver

6. gall bladder

7. pancreas

8. small intestine

9. large intestine

10. rectum

11. anus

what happens at each stage of digestive system?

1. mouth - mechanical digestion = teeth, chemical = amylase

2. salivary glands - produces amylase

3. oesophagus - muscular tube mouth → stomach (peristalsis)

4. stomach - muscle bag, protease, HCl to kill pathogens

5. liver - produces bile - emulsifies lipids into droplets for greater SA, alkaline = balances PH

6. gall bladder - stores bile

7. pancreas - secretes enzymes

8. small intestine - products of digestion are absorbed

9. large intestine - water absorbed

10. rectum - stores faeces

11. anus - excrete faeces

what is the lock and key theory?

• Substrate of the reaction fits into the active site of the enzyme - complimentary shape

• the enzyme and substrate bind, reaction takes place rapidly

• once complete, products are released

• enzyme can be used again

what are 4 things enzymes do?

• controls metabolism

  • build large molecules from lots of smaller ones

  • changing one molecule into another

  • breaking down insoluble molecules into soluble ones