Enzymes Flashcards
(23 cards)
What are enzymes?
biological catalysts which increase the rate of a reaction (in living organisms) without being used up or changed.
How do enzymes speed up useful chemical reactions in the body?
by breaking down complex molecules that we eat e.g. lipids, proteins and carbohydrates
What do enzymes do with molecules?
They can break up large molecules or join small ones.
What are enzymes made of?
Proteins
What are all proteins made up of?
chains of amino acids
How do enzymes have an active site?
amino acid chains fold into unique shapes that are vital to enzyme function - each enzyme has its own active site where the substrate binds.
What do you call the substance that takes part in the chemical reaction and fits into the active site?
substrate
How do enzymes relate to substrate?
They are substrate specific coz the shape of the substrate and the enzymes active site are compulsory.
How do enzymes interact with substrates?
Substrate collides with the active site of the enzyme and binds to it, the reaction takes place and the products are released from the surface of the enzyme.
How is low temp a physical factor that affects enzyme activity?
the number of successful collisions between the enzyme and the substrate is reduced coz their movement decreases and so the reaction is slow.
How is high temp a physical factor that affects enzyme activity?
Human enzymes work best at 37°C which is the human boy temp, the rate of reaction increases with an increase in temp because they have more energy to move around with resulting in more successful collisions.
What happens to the rate of reaction when the temp goes over the optimum temp?
The rate of reaction decreases rapidly, eventually stopping
What happens to an enzyme when the temp goes over the optimum?
the bonds break causing the active site to denature (change shape) and the substrate can no longer fit so the enzyme no longer works
How does pH affect enzyme activity?
Affects bonds holding them together. pH too low = slow reaction. High pH = denature
What is usually the optimum pH? What about exceptions?
Usually 7. Lower for enzymes in stomach cos of HCl
Optimum pH for salivary amylase?
6.8
Pepsin optimum pH
1.5-2
Pancreatic protease (trypsin) optimum pH
7.5 -8
What are the major nutrients the body needs?
Carbohydrates, proteins and lipids
Why do these nutrients need to be broken down before being reassembles?
They’re big molecules and can’t pass thru the wall of the small intestine and be absorbed into the blood
Why can they be easily absorbed after being broken down?
smaller, soluble and can pass thru easily
Why is cellulose important?
It’s made up of glucose and makes up plant cells walls. Plants are important part of diet and can’t be broken down by digestive system so need to be broken down by the gut
