biology chapter 5 Flashcards
what is a catalyst
a substance that increases the rate of a chemical reaction and is not changed by a reaction
what is an enzyme
biological catalysts that can increase the rate of a chemical reaction, without being chemically changed by the reaction. They are made up of proteins and are involved in all metabolic reactions
what reactions do enzymes catalyse
- reactions in digestion ( some food molecules are large and insoluble in water. these molecules cannot diffuse through the cell membrane. )
- reactions that build up or break down complex substances ( besides digestion, other biological reactions also require one or more enzymes as catalysts)
what does it mean by digestion
the process of breaking down food molecules into smaller substances is known as digestion
what are food digested by
foods are digested by digestive enzymes
what are some of the digestive enzymes
amylase, maltase, protease, lipase
what is the function of an amylase
digest starch into maltose
what is the function of a maltase
digest maltose to glucose
what is the function of a lipase
digest fats to fatty acids and glycerol
what is the function of a protease
digest proteins to amino acids
how are enzymes named
enzymes are names according to a scientific system. the name of each enzymes shows the substance on which the enzyme reacts and end in ‘ase’
how are enzymes classified
enzymes are classified according to the substances they act. for example:
- carbohydrates digest carbohydrates
- proteases digest proteins
- lipase digest into fats (lipids)
how does an enzyme work
the substances on which enzymes act are called substrates. each enzyme has a groove on its surface called the active site. only a substance with a complementary shape can fit into the active site
what happens when substrates bind to the active site of the enzyme
when the substrate binds to the active site of an enzyme, an enzyme- substrate complex is formed.
what are the characteristics of enzymes
- enzymes catalyse reversible reactions
- every enzyme has an optimum pH at which is most active
- enzymes are required in minute amounts
- enzymes are specific in action
- every enzyme has an optimum temperature at which is most active
describe the structure of the enzymes
enzymes are proteins that contain a highly specific active site that fits into a specific substrate
why are enzymes necessary to biological systems
they speed up reactions so that less energy is required for the reaction to occur
describe the enzyme action
a substrate that fits the specific active site of the enzyme binds to create an enzyme substrate complex, a reaction occurs and then the products are released
what does the statement “enzymes are highly specific” mean
the active site of the enzyme must bind with the substrate that has a complementary shape so that specific actions can be catalysed
state the four factors that affect the rate of an enzyme controlled reaction
temperature, pH level, substrate concentration, enzyme concentration
describe the effect of temperature on the rate of an enzyme controlled reaction
as the temperature increases, the rate of the reaction increases. once the temperature exceeds the optimum temperature, the enzyme becomes denatured and the rate of the reaction decreases
why does the rate of an enzyme controlled reaction increase when the temperature increases
as the temperature increases, the particles gain more kinetic energy. this increases the collisions between molecules and later leading to a reaction
if the temperature increases above the optimum, how does this affect the enzyme function
the active site will be distorted as the enzyme denatures and so it will no longer fit the substrate
describe the effect of the pH on the rate of an enzyme controlled reaction
the rate of an enzyme catalysed reaction is the fastest at the optimum pH. If the pH is too high or low, the enzyme will work less efficiently and the active site may be denatured at extremes of pH
