Proteins Flashcards
How many amino acids are there?
20
What dictates a proteins function
Order of amino acids the way they fold
What examples are there of proteins?
All enzymes
All antibodies
Haemoglobin
What makes up an amino acid?
An anime group (NH2)
A CH in the middle
A variable group
A carboxyl group (COOH)
How can you denote the variable group in amino acids?
With the letter R
What bond is formed between 2 amino acids?
Peptide bond
Describe how a dipeptide is formed
The amine group from 1 amino acid lines up with the carboxyl group from the other amino acid
The OH in the carboxyl group joins with a H in the amine group to form water
The N and C now can form another bond with each other (peptide bond)
This is a condensation reaction.
What is primary structure?
It is the order the amino acids join up forming a polypeptide
1000s of amino acids can join up
Where are polypeptides made?
Ribosomes and rough ER
What is secondary structure?
How the chain folds up on itself
What are the 2 secondary structures?
Alpha helix
Beta pleated sheet
Describe the bonding in secondary structure
Hydrogen bonds hold them in position
Individually they are weak but there are lots of them it is strong
What is tertiary structure?
How the polypeptide chain fold up on itself again
More complex shapes are made
What are the 4 bonds in tertiary structure (strongest to weakest)
Disulfide bond/bridge
Ionic bonds
Hydrogen bonds
Hydrophobic/hydrophilic interaction
Describe disulfide bonds (tertiary structure)
Adjacent cysteine amino acids form strong covalent bonds between sulfur
How do you break a disulfide bond?
Using a reducing agent
Describe ionic bonding (tertiary structure)
Forms between ionised amine and carboxyl groups
How do you break the ionic bonds in tertiary structure?
Extreme pH
Describe hydrogen bonding in tertiary structure
Forms between delta- oxygen and delta+ hydrogen
Describe hydrophilic/hydrophobic interaction (tertiary structure)
Between non polar R groups
Hydrophilic go towards water (outside)
Hydrophobic go away from water (inside)
Describe quaternary structure
More than 1 polypeptide joined together
Any bonds used in tertiary structure can be used
What is a conjugated protein?
A protein that has a non-protein prosthetic group
Which 3 proteins are globular?
Haemoglobin
Insulin
Enzymes eg catalase
Which 3 proteins are fibrous?
Collagen
Keratin
Elastin
What is the structure of haemoglobin?
4 chains
Contains a prosthetic haem group that contain Fe2+ ions
What are the properties of haemoglobin?
Soluble
Haem group works reversibly with oxygen
What is the function of haemoglobin?
Combines with oxygen/carbon dioxide and transports it in red blood cells
Structure, properties and function of collagen
3 chains
Tensile strength/insoluble
Part of tendons, skin and cartilage
Structure, properties and function of keratin
2 chains, disulfide bonds
Insoluble, inflexible/strong
Waterproofs cells
Structure of insulin
81 amino acids
2 chains held together by disulfide bonds
Properties of insulin
Soluble
Has polar groups
Function of insulin
Regulates blood glucose concentration
Structure of enzymes eg catalase
2000 amino acids
4 chains
Has prosthetic haem group containing Fe2+ ions
Properties of enzymes eg catalase
Soluble
Function of enzymes eg catalase
Breaks down hydrogen peroxide quickly
Structure, properties and function of elastin
Fibrous
Stretches and recoils, insoluble
Blood vessels and alveoli contain elastin
What makes proteins soluble?
Having hydrophilic/hydrophobic parts
What are the properties of fibrous proteins?
Insoluble
Strong
Unreactive
Have structural roles
What is the difference between tertiary and quaternary
Quaternary includes other polypeptide chains and prosthetic groups
What are the properties of globular proteins?
Compact
Soluble
Have metabolic roles
