Proteins Flashcards
What are the elements proteins contain?
Carbon, hydrogen, oxygen, nitrogen and sometimes sulphur.
What are the monomers making up proteins?
Amino acids.
What reaction joins and splits amino acids?
Joins - condensation reaction
Splits - Hydrolysis reaction
What is the bond joining amino acids together?
Peptide bond.
What are the different components of a polypeptide chain?
Left - Amine group consists of N and 2 H
Next - Carbon with hydrogen and R group attached
Right - Carboxyl group contain C double bond O and OH.
What is the primary structure?
This is the precise number and sequence of amino acids in the polypeptide chain.
What is the primary structure determined by?
The genetic code in DNA.
What are the bonds present in primary structure?
Only bond present are peptide bonds.
What does the primary structure determine?
Determines how the protein twists and folds into its final shape.
What happens in secondary structure?
The hydrogen/oxygen/nitrogen atoms in the polypeptide primary structure interact to form hydrogen bonds, holding the structure in a secondary shape.
What shape does the hydrogen bonds in the secondary structure form?
Either alpha helix or beta-pleated sheets.
What is the tertiary structure?
-How the protein folds up into its specific 3D shape.
- Involves R-groups of different amino acids in the secondary structure interacting with each other when they are close enough to do so.
What are the bonds present in the tertiary structure?
- Hydrophilic/hydrophobic interactions
- Hydrogen bonds
- Ionic bonds
- Disulphide bonds/bridges
Which bonds are the strongest and weakest in the tertiary structure?
Strongest - Disulphide bonds/bridges
Weakest - Hydrogen bonds
Features of a globular protein.
- compact
- water soluble
- spherical in shape.
What is insulin and what are the features?
- A hormone involved in regulation of blood glucose concentration.
- soluble as hormones need to be transported in the bloodstream.
- have specific shape due to having to fit on specific receptors on cell-surface membrane.
What are conjugated proteins?
-globular proteins that contain a non-protein component known as prosthetic group.
Features of haemoglobin.
- Conjugated protein, globular protein.
- Made from 4 polypeptide chains joined together.
- Carries oxygen around body in red blood cells.
- Prosthetic group is haem group. This contains iron, which oxygen binds to.
Features of insulin.
- Globular protein.
- Made from 2 polypeptide chains joined together.
- A hormone secreted by the pancreas. It helps to regulate the blood glucose level.
- It is soluble - which means it can be transported in the blood to the tissues where it acts.
Features of amylase.
- Globular protein.
- Made from one polypeptide chain twisted and folded.
- Amylase is an enzyme that catalyses the breakdown of starch in the digestive system.
- Secondary structure of this protein contains sections of alpha helix and beta-pleated sheets.
Characteristics of fibrous proteins.
- Not water soluble.
- Limited range of amino acids, and have a repetitive primary structure.
Examples of fibrous proteins.
- Keratin.
- Elastin.
- Collagen
Features of keratin.
- Strong and fairly flexible.
- Made from 2 parallel alpha-helices twisted around each other.
- Contains many disulphide bridges forming strong, inflexible and insoluble materials.
-The degree of disulphide bridges determines the flexibility- hair contains fewer bonds making it more flexible than nails, which contains more bonds.
Features of elastin.
- A fibrous protein found within elastic fibres e.g. walls of blood vessels.
- Made up from many stretchy protein fibres called “tropoelastin”.
- These have the ability to “stretch and recoil”.
- When we breathe in, our alveoli stretch. When we breathe out, our alveoli recoil.
