protein

• what are proteins

  Proteins are made up of amino acids

  Amino acids are the building blocks of proteins, which are essential macromolecules involved in various functions within living organisms.

  Amino acids are monomers and can join together via peptide bonds to form dimers (dipeptides) and polymers (polypeptides). 
• protein

  
• What are the roles of proteins?

  Functions of proteins in living organisms:

  • Enzymes These proteins are used to breakdown and synthesise molecules.
  • Antibodies These proteins are involved in the immune response.
  • Transport Some proteins can move molecules or ions across membranes.
  • Structural components - Proteins like keratin and collagen are used to create strong fibres.
  • Hormones Some of these are proteins that act as chemical messengers in the body.
  • Muscle contraction - Muscles are made up of proteins.
• what is the structure of amino acids Amino acid structure

  There are around 20 different amino acids that are commonly found in living organisms. 
• amino acid strcutre

  
• Amino acid structure

  There are around 20 different amino acids that are commonly found in living organisms. 

  They all have the same general structure:

  • A central carbon atom
  • An amino group (-NH2)
  • A carboxyl group (-COOH)
  • A hydrogen atom (-H)
  • An R group or a variable side group

  Each amino acid has a different R group which determines its properties. For example, amino acid cysteine contains a sulphur atom in its R group. This allows cysteine to form disulphide bonds.
• Dipeptide synthesis and breakdown

  Dipeptides are synthesised via condensation reactions and broken down via hydrolysis reactions. These reactions involve the formation or the breakdown of a covalent bond known as a peptide bond.
• condensation reaction


  When two amino acids join, the hydroxyl (OH) in the carboxyl group of one amino acid reacts with the hydrogen (H) in the amino group of another amino acid. This releases a water molecule (H2O) and forms a peptide bond between the carbon of one amino acid and the nitrogen of another. 

  
• hydrolosis reaction


  When a water molecule (H2O) is added to a dipeptide, the peptide bond is broken to release the two amino acids.

  
• Proteins have complex 3D structures

  Proteins are large, complex molecules with unique 3D structures. It's this unique structure that allows them to carry out their specific function.

  We can think of protein structure in four main levels:

  1. Primary
  2. Secondary
  3. Tertiary
  4. Quaternary

  Each level has specific bonds that hold it together and influence the overall shape.
• what is the primary structure Proteins have complex 3D structures

  Proteins are large, complex molecules with unique 3D structures. It's this unique structure that allows them to carry out their specific function.

  We can think of protein structure in four main levels:

  1. Primary
  2. Secondary
  3. Tertiary
  4. Quaternary

  Each level has specific bonds that hold it together and influence the overall shape.
• primary structure

  
• secondary structure: The secondary structure involves hydrogen bonds forming between the amino group of one amino acid and the carboxyl group of another amino acid further down the chain. This causes the polypeptide chain to coil into either an alpha-helix or a beta-pleated sheet structure.

  
• the tertiary strcuture: the tertiary structure forms when the polypeptide chain folds and twists further to create a complex 3D structure.

  This specific structure is held together by many bonds, including: 

  • Hydrogen bonds - These are individually weak but provide strength in large numbers.
  • Ionic bonds These form between positive and negative R groups.
  • Disulfide bridges - These form between R groups that contain sulphur (such as cysteine).
  • Hydrophobic and hydrophilic interactions - These are weak interactions between polar and non-polar R groups.

  
• Quaternary structure :The quaternary structure involves two or more polypeptide chains held together by the same bonds found in the tertiary structure of a protein (hydrogen bonds, ionic bonds, disulfide bridges, and hydrophobic and hydrophilic interactions).

  It can also involve the addition of non-protein groups known as prosthetic group

  
• Not all proteins have a quaternary structure

  It is important to understand that although all proteins have primary, secondary, and tertiary structures, only some proteins have a quaternary structure.

  This means that some proteins consist of a single polypeptide chain, but others are made up of multiple chains combined. 
• comparing the protein structure