3 & 4Food energy and Digestion Flashcards
Name the enzyme found in saliva
Amylase
Define enzyme
Protein molecules that act as biological catalysts, increasing the rate of biological reactions without being used up
Enzymes operate through the use of a mechanism called the ……?
Lock and key model
Each enzyme is ….. to 1 particular molecule
Specific
The molecule to which the enzyme reacts with is called the ….
Substrate
Why are enzymes specific?
Due to the presence of a uniquely shaped pocket on the surface of the enzyme known as the active site
Why are chemical reactions affect by temperature?
Due to kinetic theory
What part of the enzyme is changed in high temperatures
The active site
What happens to enzymes when exposed to high temperatures?
They become denatured
Maximum enzyme activity occurs at the optimum temperature of ….
36-40 degrees Celsius
Pepsin (protease) acts in …. …. in the …..
Acidic conditions … stomach
Inhibitors definition
inhibitors are molecules that fit the active site but are not broken down
Give the substrate and products of the following enzyme:
Amylase-
Protease-
Lipase-
Amylase substrate: starch
Products: simple sugars, glucose
Protease substrate: proteins
Products : amino acids
Lipase substrate: lipids
Products : Glycerol and fatty acids
Give a commercial use of enzymes (2)
- Many biological washing powders have enzymes for breaking down difficult to remove stains.
- These enzymes are thermostable - they can work at a wide range of temperatures and they break the complex, large and insoluble stains down into small, soluble molecules that dissolve in the water
Certain molecules have a shape that is similar to the substrate, allow them to … into the …. … of the enzyme but are not …. …..
Fit , active site , broken down
What is pepsin’s optimum pH ?
Around 3
Digestion continues in the upper parts of the small intestine (the ….. and ….. ) and is complete in the …..
Duodenum and jejenum .., ileum
During digestion the large insoluble biomolecules (….., ….. and …. ) have all been broken down into small soluble molecules that can enter the bloodstream through a process known as ….. .
proteins, lipids and starch
Absorption
Name five features of the ileum which increase the efficiency of absorption and explain them
- Approximately 3m long, increases the surface area
- highly folded form along its length, increases the surface area
- excellent blood supply, maintains the concentration gradient required
- thin (1 cell thick), highly permeable walls, reduces the diffusion distance
- presence of villi, further increases the surface area
What do villi contain and what are they responsible for ?
They contain lacteals and these are responsible for the absorption of fatty acids and glycerol. These molecules then travel through the lymphatic system and join the blood steam in another part of the body
The walls of villi are made of a single layer specialised cells. What are they called?
Epithelial cells
Amylase acts in neutral slightly ….. conditions in the mouth
alkaline
Equation for the energy released from food per gram (J)
mass of water (g) x temp. rise x 4.2
———————————————
mass of food sample (g)
How does low temperature affect an enzyme?
Low temperature causes reduced rates of collision between substrate and enzyme
When does denaturing of the enzyme occur ?
It occurs increasingly at levels above the optimum
What chemical elements make up carbohydrates and fats/lipids
All carbohydrates contain the chemical elements carbon (C), hydrogen (H) and oxygen (O).
How are villi adapted to absorption?
- villi aid absorption due to their excellent blood supply
How do the surface epithelium cells aid absorption?
They are a single layer of cells that reduce the number of cells between the lumen of the gut and the capillaries and lacteals
Define digestion
The breakdown of large, complex, insoluble molecules into small, simple, soluble ones
