Session 4.1e - Pre-Reading [What is a Protein] Flashcards
https://www.youtube.com/watch?v=qBRFIMcxZNM
What are the roles of proteins in biology?
Proteins play countless roles throughout the biological world - from catalysing chemical reactions to building the structures of all living things e.g. collagen, insulin and antibodies are all proteins.
What are the building blocks of proteins?
Despite this wide range of functions, all proteins are made out of the same 20 building blocks, called amino acids.
All proteins are made out of the same 20 building blocks, despite proteins having a wide range of functions. How does this occur?
The way these 20 amino acids are arranged dictates the folding of the protein into its unique final shape and its function.
What atoms are amino acids made up of?
Carbon Oxygen Nitrogen Hydrogen Sulfur
What is every amino acid contain?
- Amino group
- Carboxyl group
- Side chain
attached to a central carbon atom.
Which part of the amino acid is unique?
The side chain
What does the side chain of amino acids do?
Because it is the only part of the amino acid that is unique, it determines each amino acid’s chemical properties.
What are the properties of hydrophobic amino acids?
Hydrophobic amino acids, such as leucine and isoleucine, have carbon-rich side chains, which don’t interact well with water.
What are the properties of hydrophilic amino acids?
Hydrophilic amino acids, such as serine, or threonine, interact well with water.
What do charged amino acids interact with?
Charged amino acids, like glutamic acid (acidic) or arginine (basic) interact with oppositely charged amino acids or with water.
What is the primary structure of a protein?
The primary structure of the protein is the linear sequence of amino acids as encoded by DNA.
How are amino acids joined in the primary structure of a protein?
The amino acids are joined by peptide bonds, which link an amino group and a carboxyl group.
What is released each time a peptide bond is formed?
A water molecule is released each time a bond is formed.
What gives proteins their distinct shapes and chemical characteristics?
Specific amino acid sequences give proteins their distinct shapes and chemical characteristics
What do primary structures of a protein then go on to form?
These protein chains often folds into two types of secondary structures stabilised by hydrogen bonds.
What are the properties of the alpha helix secondary structure?
A protein chain can fold into a rigid alpha helix, forming regular patterns of hydrogen bonds between the backbone atoms of nearby amino acids.
What are the properties of the beta sheet secondary structure?
Backbone atoms of the chain can interact side-by-side to form beta sheets.
Describe a common tertiary structure of a protein.
Many proteins fold into a compact globular shape, with hydrophobic side chains sheltered inside away from the surrounding water
Give an example of a protein that relies of the globular tertiary structure.
The functions of many proteins rely on this folded structure: for instance, haemoglobin forms a pocket to hold haem.
What is haem?
A small molecule with an iron atom in the centre that binds oxygen.
What is the quaternary structure of a protein?
Two or more polypeptide chains can come together to form one functional molecule with several subunits.
Give an example of a protein whose function relies on the subunit component of the quaternary structure.
The four subunits of haemoglobin cooperate so that the complex can pick up more oxygen in the lungs and release it in the body.
Why is molecular shape important to function?
Many proteins rely on the ability to recognise the shape of specific molecules in order to function correctly.
Give an example of how molecular shape is used in defence?
The flexible arms of antibodies protect the body from disease by recognising and binding to foreign molecules and thus preventing the viral RNA or DNA to enter the cell.
Give an example of how molecular shape is used in structure?
Collagen forms a strong triple helix that is used through the body for structural support.
Give an example of how molecular shape is used in transport?
The calcium pump moves ions (calcium ions) across cell membranes allowing the synchronised contraction of muscle cells.
Give an example of how molecular shape is used in communication?
The hormone insulin is a small, stable protein that can easily maintain its shape while travelling through the blood to regulate blood sugar levels.
Give an example of how molecular shape is used in enzymes?
Alpha amylase is an enzyme with a catalytic site that begins the breakdown of carbohydrates in our saliva.
Give an example of how molecular shape is used in storage?
Ferritin forms a hollow shell that stores iron from our food.
What are the standard amino acids?
Glycine (G), Alanine (A), Serine (S), Threonine (T), Cysteine (C), Valine (V), Leucine (L), Isoleucine (I), Methionine (M), Proline (P), Phenylalanine (F), Tyrosine (Y), Tryptophan (W), Aspartic acid (D), Glutamic acid (E), Asparagine (N), Glutamine (Q), Histidine (H), Lysine (K), Arginine (R).
How is the primary structure of a protein formed?
The amino group and carboxyl group of adjacent amino acids are joined by a polypeptide bond, releasing water. This forms the protein backbone.
What are the two types of secondary structures?
Alpha helix
Beta sheet
How are secondary structures stabilised?
By hydrogen bonds
Which secondary structure involves regular hydrogen bonds between the backbone atoms of nearby amino acids?
Alpha helix
Which secondary structure involves regular hydrogen bonds between the backbone atoms of amino acids side-by-side?
Beta sheets
The compact globular shape of a protein is an example of which structure in proteins?
Tertiary structure
Where do hydrophobic side chains of amino acids lie?
Sheltered inside, away from surrounding water
Where does haemoglobin interact with oxygen?
It picks up oxygen in the lungs via capillaries and releases it into the body.
Where are haemoglobin molecules found?
In red blood cells
How many haemoglobin molecules in each red blood cell?
There are about 280 million haemoglobin molecules in each red blood cell
What are the functions of proteins?
Defence Structure Transport Communication Enzymes Storage
What does insulin bind to?
Insulin receptors
