Proteins Flashcards
What elements are present in all proteins?
Carbon, hydrogen, oxygen and nitrogen
What are the monomer units that make up a protein?
Amino acids
Draw the structure of an amino acid.
What are the bonds called that join amino acids together?
Peptide bonds
In what type of reaction is a peptide bond formed?
Condensation reaction
What is a polypeptide?
Many amino acids joined together by peptide bonds
Describe exactly how amino acids are joined by peptide bonds in terms of the atoms?
The hydroxyl group of 1 amino acid reacts with a hydrogen in the amine group of another amino acid. This forms water.
What group makes each amino acid different?
R-group
What is it that causes proteins to have different structures?
Different sequences of amino acids leads to different structures with different shapes.
What bond holds together the primary structure of a protein?
Peptide bonds
Describe the primary structure of a protein?
Amino acids are joined in a polypeptide chain by polymerisation.
What bond holds together the secondary structure of a protein?
Hydrogen bonds
There are two ways the chains arrange themselves in the secondary structure of a protein. What are they?
Alpha helix and beta pleated sheet
Describe the tertiary structure of a protein
The folded/coiled amino acid chains are coiled and folded into their final structure.
What bonds hold together the tertiary structure of a protein?
Hydrogen bonds, ionic bonds and disulphide bonds/bridges
Which is the weakest bond in proteins?
Hydrogen bonds.
Which is the strongest bond in proteins?
Disulfide bond.
What is the quaternary structure of a protein?
The final 3D structure of a protein.
Where are proteins made in the cell?
The cytoplasm
Name the 3 types of proteins
Globular, conjugated and fibrous
Name 3 properties of globular proteins
Compact. Water soluble. Slightly spherical shape.
What makes globular proteins soluble?
Hydrophobic R-groups are folded away from aqueous environment and hydrophilic R-groups are folded on the outside of the protein.
Give an example of a globular protein.
Insulin.
What is the difference between conjugated protein and simple proteins?
Conjugated proteins have a non protein component called a prosthetic group. Simple ones don’t.
Finish the sentences. 1) Lipoproteins are made when ______ combine with proteins. 2) _______ are when carbohydrates combine wthe proteins.
1) Lipids 2) Glycoproteins
Name 2 conjugated proteins.
Haemoglobin. Catalase.
Describe the structure of fibrous proteins.
Strong, long molecules with repetitive primary sequence.
Name 3 fibrous proteins.
Keratin. Elastin. Collagen
What makes keratin so strong?
Amino acids with R-groups containing sulfur create disulfide bridges (really strong)
How is elastins structure related to its function in blood vessel walls?
Made from stretchy molecules called tropoelastin so it can stretch without breaking. Important for blood flow at high pressure.
Where is collagen found?
A connective tissue found in skin, tendons, ligaments.
What denatures a protein?
Changes in temperature, salt or pH concentration can all denature a protein
What happens to fibrous proteins when denatured?
They lose their structural strength.
What happens to globular proteins when denatured?
They become insoluble and inactive.
What is catalase?
An enzyme that catalyses the breakdown of hydrogen peroxide in the body which is harmful to us.
