2. Organisation (digestion, factors affecting enzymes and food tests) Flashcards
What are the 8 steps of digestion?
- Food enters our mouth and is broken down mechanically using teeth. If any carbohydrates are present, the salivary gland will secrete carbohydrase enzymes to break them down
- The food travels through the esophagus into the stomach
- The muscular walls of the stomach contract and churn the food. It also produces protease enzymes
- When the food is travelling to the small intestine, the gall bladder releases bile and the pancreas releases protease, amylase and lipase enzymes
- protease enzymes break down proteins into amino acids, amylase breaks down starch into glucose and lipase enzymes breaks down lipids into fatty acids and glycerol in the small intestine
- In the small intestine, villi cells will absorb the nutrients into the bloodstream
- All that is left is excess water and waste, so excess water is absorbed in our large intestine
- All the remaining waste will go down the rectum and all the indigestible food is stored then released through the anus
What is mechanical digestion?
When food is broken down using the teeth
What is the lock and key mechanism based around?
- It is based around the idea that the enzyme and the substrate need to be specific to each other in order to fit together
- The substrate has to be a complementary shape to the enzyme in order for it to be broken down.
What shape does an enzyme have to have to the substrate?
Specific and complementary shape
What are the steps for enzyme digestion?
- Enzyme has a specific and complementary shape to the substrate
- The substrate binds to the active site on the enzyme, forming an enzyme-substrate complex
- The enzyme breaks down the substrate into smaller products
- products are then absorbed into the blood
What is the active site?
The section on an enzyme where the substrate binds to
When does an enzyme-substrate complex form?
It forms when the substrate binds to the enzyme
What 3 factors affect enzymes?
- Temperature
- pH
- Substrate concentration
What is the optimum?
The condition at which the rate of reaction is at its highest
What does denature mean?
- The shape of the enzymes active site changes so it is no longer specific and complementary to the substrate
- So it can no longer fit and break down the substrate
What happens to the rate of reaction as temperature increases for enzymes?
- As temperature increases, the rate of reaction also increases. This is because as the temperature increases, the particles gain more kinetic energy
- This means there will be more successful collisions, so more enzyme-substrate complexes are formed per second
- Temperature increases until the optimum. This is where the rate of reaction is at its highest.
- if temperature continues to increase beyond the optimum the enzyme will begin to denature
- This means the active site will change shape and will no longer be specific and complementary to the substrate
- So less enzyme-substrate complexes form, so the rate of reaction decreases
What happens to the rate of reaction when enzymes optimum pH is exceeded?
- Exceeding optimum pH will mean the enzyme will denature
- This means the active site will change shape and will no longer be specific and complementary to the substrate
- This means fewer enzyme-substrate complexes will form, so the rate of reaction decreases
What happens to the rate of reaction as the substrate concentration increases?
- As substrate concentration increases there are more enzyme-substrate complexes being formed more frequently
- So the rate of reaction increases
- So substrate concentration is the limiting factor
What happens to the rate of reaction as the substrate concentration continues to increase?
- As the substrate concentration continues to increase the rate of reaction stays the same/plateus
- This means that all the enzymes active sites are occupied
- So the substrate concentration is no longer the limiting factor for the rate of reaction
What is the food test for protein?
Biuret reagent
