UNIT ONE Biological Molecules - Proteins and Enzymes Flashcards
Explain why proteins are important to the body by describing their variety of functions
Antibodies = proteins that fight infection in the body
Haemoglobin = found in red blood cells and used to transport oxygen around the body
Enzymes = biological used in the digestion of food molecules
Describe the structure of an amino acid
An amine group : H - N - H
An R-group : R - C - H
A carboxyl group : O = C - O - H
Define an Amino acid
The monomers form which proteins are made
Define a Dipeptide
a dipeptide is a protein formed by the condensation of two amino acids
Define a polypeptide
A polypeptide is a protein formed by the condensation of many amino acids
How are dipeptides / Polypeptides formed
These proteins are formed during a condensation reaction between amino acids
- Dipeptides are formed during the condensation reaction of 2 amino acids
- Polypeptides are formed during the condensation of many amino acids
These amino acids are joined by a peptide bond which forms between the carboxyl group of one amino acid and the amine group of another
Describe the 4 level of protein structure
Primary Structure = the number and sequence of amino acids in a polypeptide chain
Secondary structure = the folding of the polypeptide chain into an alpha helix or a beta pleated sheet held together by hydrogen bonds between the NH group of one amino acid and the c=o group of another
Tertiary Structure = folding of the polypeptide chain into a 3D specific shape held together by hydrogen, ionic and disulphide bonds between R- groups of different amino acids
Quaternary structure = more than one polypeptide chain joined together
Describe the Biruet test and how it can be interpreted
First add Biruet solution to a sample
A colour change from blue to purple/lilac will appear if a protein is present
Define an enzyme
A biological catalyst that speeds up a rate of reaction by lowering the activation energy required
Explain the induced fit model theory
First the substrate enters the enzyme active site , the binding of the substrate molecule induces the change in shape of the active site.
This puts pressure on the bonds in the substrate as they bend, causing them to be more easily broken.
This explains how enzymes lower activation energy as the substrate bonds are already bent/ under pressure so can broken more easily and quicker
Explain how temperature effects enzyme activity
An increase in temperature causes an increase in enzyme activity as substrate and enzyme molecules have more kinetic energy .
There are more likely to be successful collisions between enzymes and substrate causing more enzyme-substrate complexes to form
Explain how PH level effects enzyme activity
Enzymes are sensitive to PH, so below or above the optimum PH of an enzyme its activity decreases. If PH alters from the the R group of the amino acids are altered and hydrogen and ionic bonds in the tertiary structure are broken, changing the shape of the active site so that it is no longer complementary to the substrate. As a result no more enzyme-substrate complexes can form as the enzyme is denatured.
Explain how substrate concentration effects enzyme activity
Adding more substrate initially increases enzyme activity as more enzyme substrate complexes can form . However at high substrate concentrations there are no free active sites and the maximum number of enzyme substrate complexes form. As a result activity plateaus.
Explain how enzyme concentration effects enzyme activity
Initially adding more enzymes increases activity as more enzyme substrate complexes can form. At high enzyme concentrations activity plateaus as there isn’t enough substrate to form more enzyme substrate complexes
How do competitive inhibitors effect enzyme activity
Competitive inhibitors are similar in shape to substrate and can enter an enzymes active site and prevent substrate from binding. As a result less enzyme substrate complexes can form, lowering activity rate.
