Enzyme Action Flashcards
What type of protein are enzymes
Globular
What are the chemical reactions required for growth
Anabolic- building up -catalysed by enzymes
What are breaking down reactions called
Catabolic e.g. break down of large organic molecules like glucose-also requires enzymes.
Digestion is catalysed by enzymes aswell
What is metabolism
The sum of all of the different reactions and reaction pathways happening in a cell or an organism, and it can only happen as a result of the control and order imposed by enzymes.
What’s the V max
Enzymes can only increase the rates of reaction up to a certain point called the V max
How does a reaction happen
Molecules need to collide in the right orientation. When high temperatures and pressure are applied the speed of the molecules will increase, therefore so will the number of successful collisions and the overall rate of reaction.
What’s the SPECIFICITY of an enzyme
Many different enzymes are produced by living organisms, as each enzyme catalyses one biochemical reaction, of which there are thousands in any given cell.
What’s the activation energy
Energy needs to be supplied for most reactions to start. Enzymes help molecules collide successfully, and therefore reduce the activation energy required. There are two hypothesis for how enzymes do this.
Lock and key hypothesis
An area within the tertiary structure of the enzyme has a shape that is complementary to the shape of a specific substrate molecule. This area is called active site. Only specific substrate will fit into the active site of enzyme.
When substrate is bound to the active site an enzyme-substrate complex is formed. The substrate or substrates then react and the products are formed in an enzyme-product complex. The products are released, leaving enzyme unchanged.
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 strains on the bonds within the substrate, which also helps the reaction along.
Induced-fit hypothesis
Recent research shows active site of enzyme actually changes shape slightly as the substrate enters. The initial reaction between enzyme and substrate is relatively weak, but these weak interactions rapidly induce changes in the enzymes tertiary structure that strengthen binding, putting strain on the substrate molecule. This can weaken a particular bond or bonds in substrate, therefore lowering activation energy for reaction.
Intracellular enzymes
Enzymes that act within cells are called intracellular enzymes
Hydrogen peroxide is a toxic product of many metabolic pathways. The enzyme catalase ensures hydrogen peroxide is broken down to oxygen and water quickly, preventing accumulation. Found in both plant and animal tissues.
Extracellular enzymes
Nutrients are often in form of polymers such as proteins and polysaccharides. These large molecules cannot enter cell directly through cell-surface membrane. Need to be broken down. Enzymes are released from the cell to break down these large nutrient molecules into smaller molecules in the process of digestion- extracellular enzymes.
Both single-celled and multicellular organisms rely on extracellular enzymes to make use of polymers for nutrition.
How do single-celled organisms use enzymes
Eg bacteria or yeast, release enzymes into their immediate environment. Enzymes break down larger molecules like proteins and the smaller molecules produced are absorbed.
Digestion of starch
Begins in mouth and continues to small intestine.
-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 into the mouth, and in pancreatic juice into the small intestine.
-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 the cells lining the digestive system and subsequently absorbed into the bloodstream.
Digestion of proteins
Trypsin is a protease, a type of enzyme that catalyses the digestion of proteins into smaller peptides, which can then be broken down further into amino acids by other proteases. Trypsin is produced in the pancreas and released with the pancreatic juice into the small intestine, where it acts on proteins. 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 bloodstream
