Enzymes And Digestion Flashcards
What are enzymes
A biological catalyst that speeds up reactions without being used up itself
What is a enzyme made of
Proteins
How do enzymes work
The active site of an enzyme has a complimentary shape to a certain substrate meaning it is a tight fit allowing the enzyme to catalyse a reaction. The complimentary shape shows enzyme specificity, am enzyme will only work on one substrate.
What is the maximum rate of enzyme activity described as
Optimum level
What happens to enzymes and substrates at a low temp
They move slowly due to low kinetic energy. Therefore there is fewer collisions and enzyme activity is low
At what temp does maximum enzyme activity occur
Optimum temperature
What happens to an enzyme at higher temps than the optimum
They progressively denature. The higher temp changes the shape of the active site and it no longer fits the substrate
Each enzyme has a optimum pH on either side of this optimum why do they work less well
The incorrect pH changes the shape of the enzymes active site causing the complimentary fit to be less effective slowly down the rate of activity
What happens as more enzymes become available
More enzyme activity and concentration but it eventually will level off as the number of substrate molecules will become limiting
What is a inhibitor
A molecule or substance that fits loosely into an enzymes active site- they may not be the exact fit but will fit well enough to prevent normal substrates from using the enzyme. This will reduce the speed of reaction as enzymes being used by inhibitors are inactive
What is digestion
The breakdown of large, insoluble food molecules into small, soluble molecules that can be absorbed
What is absorption
The process in which small, soluble food molecules are transferred from the gut to the blood system. (In the ileum)
What are enzymes needed for in the digestive system
To break down large, insoluble food molecules into small, soluble ones that can be absorbed into the blood stream.
Where does most digestion of food take place
In the stomach and the first part of the ileum
What 3 enzymes are in the digestive system
Carbohydrase/ amylase
Protease
Lipase
What does amylase digest and what are the products of digestion
Digests starch
Produces glucose and other sugars
What does protease digest and what does it produce
Digests protein
Produces amino acids
What does lipase digest and produce
Digests fat
Produces glycerol and fatty acids
What is a catabolic reaction
Break down of large insoluble molecules into smaller soluble or molecules
What is a anabolic reaction
Build up of large molecules from smaller ones
What are enzymes made of
Amino acids, most a enzymes contain 100-1000 amino acids
The amino acids are joined in a long chain which is folded to produce a unique 3d structure
What is carbohydrase digest and produce
Digests carbohydrates to produce simple sugars
When a substrate collides with a molecule of the right enzyme and fits exactly into the active site what is this called
Enzyme-substrate complex
Explain the mouth in digestion
Teeth grinds food to increase surface area for enzyme action
Saliva is added by the salivary glands
It contains mucus ti lubricate to make it easy to swallow
It contains a digestive enzyme salivary amylase which helps break down starch into glucose
How does the food pass down the oesophagus
Wave of muscular contraction this is called peri stalsis
Explain the stomach in digestion
It contracts rhythmically, mixing the food thoroughly, turning it into a thick liquid called chyme
Glands in the lining then produce gastric juice which contains:
Protease enzyme (pepsin) this breaks down proteins into amino acids
Hydrochloric acid makes the stomachs conditions very acidic which provides a optimum pH for pepsin functioning, also kills many potentially dangerous microbes that enter along with food
What does the small intestine consist of
Duodenum and ileum
Explain pancreatic juice in the first part of the small intestine (duodenum)
It’s a juice produced from the pancreas that is secreted into the duodenum. It contains amylase, protease, lipase, carbohydrase
Explain intestinal juice
Produced by walls of the duodenum. Contains enzymes (amylase, protease, lipase and carbohydrase) to finish digestion process
Explain bile in the small intestine / duodenum
Green liquid produced in the liver and stored in the gall bladder
It’s alkaline so helps neutralise the acidic food passing from the stomach (this makes the duodenum slightly alkaline)
Emulsifies fat, breaks down large fat globules into smaller fat globules. Therefore increases the SA for lipase enzymes to break fat down,
Explain the ileum in diegetsion
2nd part of small intestine. More enzymes secreted to ensure small molecules are then absorbed into the blood by diffusion. Then when they’re in the blood they can be carried to wherever they are needed
Why does the ileum have a large SA
Allows absorption to occur quickly and efficiently as if it wasn’t a large surface area some digested food might pass out of the body before it has the chance to be digested
Features of the small intestine to have a large SA
6m long
Has folds and twists
The inner surface has millions of microscopic finger like projections called villi.
The small intestine has a good blood supply explain…
Each villus has its own network of blood capillaries. These transport products of digestion away from the small intestine once they’ve been absorbed and is replaced with blood low in digested food molecules
What does the good supply of blood to each villus ensure
A steep concentration gradient is maintained, therefore increases rate of diffusion and therefore food molecules being absorbed
How are fats absorbed differently to other food molecules
They are not absorbed through the blood capillaries on each villus but through a lacteal inside each villi. A lacteal is part of the lymph system eventually the fat molecules are returned back into the blood stream
Explain why the villi are thin
The surface of each villi is thin and permeable due to the wall only being one cell thick and the blood capillaries are also one cell thick
This makes it easier for dissolved food molecules to diffuse through to the blood capillaries as less distance to travel.
Some food we eat is indigestible why is this
We don’t have the correct enzyme to digest it
Un digested food can’t be absorbed in the ileum so it leave the ileum and enters
The colon (large intestine )
What 3 parts is the large intestine made of
Colon, rectum and anus
Explain what happens in the colon
Water is absorbed from undigested food back into the blood; colon has a large SA to do this
Explain what happens in the rectum
Faeces compacted and stored until egested
How are enzymes used commercially
May be used in biological washing powders. They are effective at breaking down a wide range of stains and also are thermostable meaning they work at a wide range of temperatures.
They may also be used in things like softening the centre of chocolates and lactose free products
Explain Lactose free products
Immobilised enzymes are used to remove lactose from milk
Product is therefore not contaminated with the enzyme lactose intolerant people can’t have
