Zusammenfassung der Ressource
Proteins
- Monomers are amino acids
- A dipeptide is when 2 amino acids are joined together
- Proteins are made up of one or more amino acid polypeptide chains
- Amino acids
- Structure is:
- The R represents a variable group, the
COOH is a carboxylic acid group, and the
NH2, the amino group
- Condensation reactions
- Amino acids are linked by condensation reactions to form a polypeptide chain, and a molecule of water
- The bonds formed are called PEPTIDE BONDS
- The reverse reactions are called HYDROLYSIS reactions, and
this is what happens in digestion
- Protein structure
- Primary structure: sequence of amino acids in the chain
- Secondary structure: the polypeptide chain doesn't remain flat and straight.
- Hydrogen bonds form between amino acids in a chain. These make it coil into and Alpha helix or a Beta pleated sheet
- Tertiary: The coiled or folded chain of amino acids is often
coiled or folded further. More bonds form between different
parts of the chain
- For protein made from a single polypeptide chain, the
tertiary structure forms their final 3-D structure
- Quaternary Structure: consists of proteins made of several different polypeptide chains held together by bonds.
- It is the way the chains are assembled together that make up the forth level of structure
- For proteins made of more than one polypeptide chain, this is their final structure
- Protein Function
- Enzymes are roughly spherical in shape due to the tight
folding of the polypeptide chains (tertiary structure)They're
soluble and often have roles in metabolism. Others help
synthesize large molecules
- Antibodies are involved in the immune response.
They're made of two light polypeptide chains and two
heavy polypeptide chains. They have variable regions-
the amino acid sequences in this region vary greatly
- Transport proteins are present in cell membranes. They
contain hydrophobic amino acids which cause the protein to
fold up and form a channel. They transport molecules and ions
across the cell membrane
- Structural proteins are physically strong. they consist
pf long polypeptide chains parallel to each other with
cross links between them. For example- keratin and
collagen