Enzymes-Basics Flashcards
What are enzymes?
Proteins that speed up metabolic reactions without being changed or used up themselves.
What do enzymes catalyse?
-Reactions that change molecules
-Catabolic reactions
-Anabolic reactions
What are Catabolic reactions?
Break molecules down
What are Anabolic reactions?
Join small molecules together
-including those that produce structural components e.g. Collagen
What are the 2 types of Enzyme action?
-Intracellular
-Extracellular
What is Intracellular enzyme action?
Inside cells
What is an example of Intracellular enzyme action?
Catalase breaks hydrogen peroxide inside hepatocytes.
What is Extracellular enzyme action?
Outside cells
What is an example of Extracellular enzyme action?
Amylase breaks starch down into maltose & trypsin & pepsin break larger polypeptides i9nto smaller polypeptides in the digestive system.
What type of proteins are enzymes?
Globular
What type of protein structure do enzymes have and what does it do for the cell?
Tertiary Structure that determine the shape of the active site.
What is the ‘original’ theory for enzyme action?
Lock and Key
What theory was the Lock and Key replaced with?
Induced Fit Model
What is the Induced Fit Model?
The shape of the active site changed slightly to fit more closely around the substrate.
How do enzymes work?
By reducing the activation energy. They do this in 2 ways.
What is the first way an enzyme reduces the activation energy?
When 2 substrates need to be joined, the are held together closely in the active site so bonds can easily form.
What is the second way an enzyme reduces the activation energy?
When a substrate needs to be broken, it fits into the active site in a way that strains the bonds so they can be broken more easily.
Where is starch digested?
Starts in mouth and continues in small intestine.
How many steps is starch digested in?
2
What is the first step in starch digestion?
-Starch polymers a partially broken down into maltose (a disaccharide).
-Amylase is involved in this stage which is produced by the salivary glands and the pancreas.
-Released in saliva in mouth and pancreatic juice in small intestine.
What is the second step in starch digestion?
-Maltose is then broken down into glucose (a monosaccharide).
-Maltose is involved in this stage which is present in the small intestine.
Glucose is small. Where can it therefore be absorbed?
By the cells lining in the digestive system and therefore into the bloodstream
How are proteins digested?
Trypepsin is a protease which catalyses the digestion of proteins into smaller peptides, then further broken down into amino acids by other proteases.
Where is Trypepsin produced and released?
Produced in pancreas and released with pancreatic juice in small intestine.
Where are amino acids produced by action of proteases absorbed?
By cells lining in digestive system and into bloodstream
