Enzymes Flashcards
What are proteins made up of?
Amino acids, 20 different amino acids can be used
What is the general structure of amino acids?
They all have the same general structure, only difference is the nature of the R group.
What is the R group for amino acids?
The R group defines the amino acid
it represents a side chain from the central ‘alpha’ carbon atom
can be anything from a hydrogen atom to a more complex ring structure
What happens when more amino acids are added to a dipeptide?
A Polypeptide chain is formed
What does a protein consist of?
More polypeptide chains folded into a highly specific 3D shape
What are the 4 levels of structure in a protein?
Primary
Secondary
Tertiary
Quaternary
What is a primary structure?
A sequence of amino acids joined together
What is a secondary structure?
Alpha helix - most globular proteins
Beta pleated sheet - structural proteins like silk
Made of hydrogen bonds - fairly weak but a lot of them
What is a tertiary structure?
Precise 3D shape eg enzyme, hormone, collegan
The 3D shape is important and if changed it will directly effect the proteins function
What is a qauternary structure?
When proteins have more than one polypeptide chain, eg. haemoglobin
Held together by ionic bonds, hydrogen bonds and disulphide bonds
Can have non-protein groups involved eg. haem group
What is the structural order of proteins?
Primary
Secondary
Tertiary
Quaternary
What are globular proteins?
Proteins that usually have spherical shape caused by tightly folded polypeptide chains
Chains are folded so hydrophobic groups are on the inside, while hydrophilic groups are on the outside
They are soluble in water.
What are some examples of a globular protein?
Enzymes
Hormones
Transport proteins
What are some globular transport proteins?
Haemoglobin, myoglobin and those embedded in membranes
What are globular enzymes?
lipase and DNA polymerase
What are globular hormones?
oestrogen and insulin
What are Fibrous proteins?
They are formed from parallel polypeptide chains held together by cross-links
They form long rope-like fibres with high tensile strength and are generally insoluble in water
What are some examples
Collagen
Keratin
Silk
What is collagen fibrous proteins?
The main component of hard connective tissue such as ligaments, tendons, cartilage
What are fibrous proteins keratin?
The main component of hard structures such as hair, nails, laws and hooves
What is fibrous proteins silk?
Forms spider webs and silkworms cocoons
What happens when heat is added to tertiary structures?
More heat leads to more kinetic energy leads to more vibrations which can break bonds
Weakest bonds break first, covalent last
Once covalent bonds are broken the enzyme is denatured
Bonds will not always reform when the protein is cooled
What does denaturing proteins mean?
If the bonds that maintain the protein’s shape are broken, the protein will stop working properly
What can cause denaturing to happen?
Changes in temperature
pH
Salt concentration
All of these vary from protein to protein
