Chapter 4- 4.1- Enzyme action Flashcards
Why are enzymes important?
Most processes in life involve chemical reactions and these reactions need to happen fast.
In a lab this would demand very high temps and pressures, but this is not possible in living cells as it would damage the cells components. Instead the reaction is catalysed by enzymes.
Enzymes are biological catalysts, globular proteins that interact with substrate molecules causing them to react much faster without the need for harsh environmental conditions.
How many reactions does each enzyme catalyse?
The specificity of the enzyme is 1.
What is meant by the term activation energy?
The energy needed to be supplied for the reactions to start. Sometimes the amount of energy needed is so large that it prevents the reaction from happening under normal conditions.
Enzymes help the molecules collide successfully and therefor reduce the activation energy required.
What is the lock and key hypothesis?
The active sit is an area within the tertiary structure of the enzyme that has a shape complementary to the shape of a specific substrate molecule.
The same way that only the right key will fit into the lock, only a specific substrate will “fit” the active site of an enzyme. This is the lock and key hypothesis.
When the substrate is bound to the active site an enzyme-substrate complex is formed.
The substrate or substrates then react and the product or products are formed in an enzyme-product complex.
The product/products are then released, leaving the enzyme unchanged and able to take part in subsequent reactions.
The substrate is held in such a way by the enzyme that the right atom groups are close enough to react. The R-groups within the active site of the enzyme will also interact with the substrate, forming temporary bonds.
These put strain on the bonds within the substrate which also helps the reaction along.
What is the active site?
An area within the tertiary structure of the enzyme that has a shape complementary to the shape of a specific substrate molecule.
What is the induced fit hypothesis?
This suggests that the active sit of the enzyme actually changes shape slightly as the substrate enters. This is a modified version of the lock and key hypothesis.
The initial interaction between the enzyme and substrate is relatively weak, but these weak interactions rapidly induce changes in the enzymes tertiary structure that strengthens the binding, therefore putting strain on the substrates molecules. This can weaken a particular bond or bonds in the substrate, therefore lowering the activation energy for the reaction.
Enzymes that act within cells are known as what?
Intracellular enzymes.
What enzyme breaks down hydrogen peroxide and what is formed?
Catalase
Oxygen an water, therefore preventing its accumulation. Both plant and animal tissues have this.
What types of enzymes are released from cells to break down larger molecules such as proteins that cannot enter cells directly through the cell surface membrane ?
Extracellular enzymes. Enzymes are released from cells to break down these larger nutrients molecules obtained from the environment or through diet into smaller molecules in the process of digestion.
Extracellular enzymes work outside the cell that made them.
In some organisms for example fungi, they work outside the body.
What are examples of extracellular enzymes involved in digestion in humans?
Amylase
Trypsin
Explain the steps of digestions of starch
It begins in the mouth then continues in the Small intestine.
1) starch polymers are partially broken down into maltose which is a disaccharide.
The enzyme involved in this stage is called amylase.
Amylase is produced by the Salivary glands and the pancreas. It is released in saliva in the mouth and in pancreatic juice into the small intestine.
2) maltose is then broken down into glucose which is a monosaccharide.
The enzyme involved in this stage is called maltase.
Maltase is present in the Small intestine.
Glucose is small enough to be absorbed by cells lining the digestive system and subsequently absorbed into the blood stream.
What is trypsin an example off?
Protease, A type of enzyme that catalyses The digestion of proteins into smaller peptides which can then be broken down further into amino acid’s by other proteases.
Where is trypsin produced?
Trypsin it’s produced in the pancreas and released with the pancreatic juice into the small intestine where it acts on protein.
The amino acids that are produced by the action of proteases are absorbed by the cells lining the digestive system and then absorbed into the blood stream
