Proteins and Enzymes Flashcards
(42 cards)
What are proteins?
Proteins are key biological molecules, usually large, that give organisms their characteristics and allow key functions to occur.
What are enzymes?
Enzymes are a group of proteins involved in almost every living process, acting as biological catalysts.
What elements do amino acids contain?
Amino acids contain Nitrogen (N), Carbon (C), Hydrogen (H), and Oxygen (O); some also contain Sulphur (S).
List three examples of proteins and their functions.
- Haemoglobin - transports oxygen
- Antibodies - defend against infection
- Enzymes - biological catalysts
What is the difference between essential and non-essential amino acids?
Essential amino acids must be ingested in the diet, while non-essential amino acids can be synthesized by the body.
What is a peptide bond?
A peptide bond is formed when two amino acids join together through a condensation reaction, resulting in the removal of water.
What are the four levels of protein structure?
- Primary structure
- Secondary structure
- Tertiary structure
- Quaternary structure
What determines the primary structure of a protein?
The primary structure is determined by the number and sequence/order of amino acids in a polypeptide chain.
What type of bonds are involved in the secondary structure of proteins?
Hydrogen bonds form between the -NH and -C=O groups on the amino acids in the polypeptide chain.
What is the tertiary structure of a protein?
The tertiary structure is the further folding of the secondary structure into a specific, complex 3D shape.
What types of bonds maintain the tertiary structure of proteins?
- Hydrogen bonds
- Ionic bonds
- Disulphide bridges
What is the quaternary structure of a protein?
The quaternary structure is formed by the association of more than one polypeptide chain.
What is denaturation in proteins?
Denaturation is the loss of the specific tertiary shape of a protein due to the breaking of bonds, often caused by high temperatures or changes in pH.
What is the Biuret test for proteins?
The Biuret test involves adding Biuret solution to a sample; a color change to purple indicates protein presence.
What is the role of enzymes as biological catalysts?
Enzymes increase the rate of chemical reactions by lowering the activation energy required.
What is the active site of an enzyme?
The active site is a specific area of the enzyme that binds to substrates, allowing the enzyme to catalyze reactions.
What is the induced fit model of enzyme action?
The induced fit model suggests that the active site changes shape to fit the substrate better upon binding.
How is the rate of enzyme-controlled reactions typically measured?
The rate is measured by the time it takes for a reaction to complete, often by recording product formation or substrate breakdown.
What happens to the concentration of substrate and product as the reaction continues?
The concentration of substrate decreases and the concentration of product increases.
What are the two causes that make it more difficult for a substrate molecule to collide with an active site?
- Fewer substrate molecules due to breakdown
- Product may block the active site.
What occurs to the rate of reaction as the substrate concentration decreases?
The rate of disappearance of substrate slows and the rate of product formation also slows.
What happens to the product graph when all substrate has been used up?
The product graph flattens out.
How can the rate of an enzyme-controlled reaction be calculated?
By dividing the change in measurement (dy) by the time taken (dx).
What two things are required to calculate the rate of a reaction?
- Concentration of reactant/product
- Time.
