Proteins

• what are proteins made from?

  proteins are polymers made from long chains of amino acids.
• What is a polypeptide?

  more than 3 amino acids linked together

  
• structure of an amino acid.

  an amino group, a carboxylic acid, and a R group (varies for each amino acid)

  
• what is the purpose of the R group ( functional group)

  it varies in different amino acids and determines their proporties.
• what is the chemical composition of an amino acid.

  1)carbon

  2)hydrogen

  3)oxygen

  4)nitrogen

  5)sulfur (only in some)
• What is a condensation reaction in proteins?

  When the amine group and carboxyl group bond through the loss of a water molecule to form a di-peptide bond.

  
• What is a hydrolisis reaction?

  where a molecule breaks down in to two parts in the presence of water.

  
• covalent bond

  A chemical bond that involves sharing a pair of electrons between atoms in a molecule

  
• hydrogen bonds

  Very weak bonds; occurs when a hydrogen atom in one molecule is attracted to the electrostaticly negative atom in another molecule

  
• disulfide bonds

  Strong chemical bonds formed when the sulfur atoms in two adjacent protein chains are joined together.
• Hydrophobic and hydrophilic interactions

  When some groups clump together within the molecule and others are more likely to be pushed to the outside; which affects how the protein folds up into final structure.
• primary protein structure

  the sequence of amino acids in a polypeptide chain, held together by peptide bonds between amino acids.

  
• secondary protein structure

  where the polypeptide chain becomes twisted or coiled and forms in to an alpha helix of a beta sheet. this is caused by hydrogen bonds formin between the -NH and -CO groups.

  
• alpha helix

  A spiral shape resulting from the coiling of a polypeptide in a protein's secondary structure, arising from hydrogen bonding between atoms.

  
• beta pleated sheet

  A type of protein secondary structure; results from hydrogen bonding between polypeptide regions running antiparallel to each other. Connected by at least two or three backbone hydrogen bonds.

  
• tertiary protein structure

  the more specific 3D folding pattern of a protein due to side chain interactions

  bonds;

  ~ionic bonds

  ~hydrogen bonds

  ~disulfide bonds

  ~hydrophilic and hydrophilic interactions.

  
• quaternary protein structure

  An association of more than one polypeptide chain bonded together to form an intricate shape.

  Can sometimes have a prosthetic group.

  
• globular proteins

  they are round, compact, and water soluble. they are alos known as functional proteins.

  ( eg. enzymes. insulin, amylase)

  
• fibrous proteins

  they are strands, and tough they are insoluble and unreactive.They are also known as structural proteins.

  (collagen, keratin, elastin)

  
• Haemoglobin

  ~oxygen carrying pigment in red blood cells

  ~haem prosthetic group (iron)

  ~4 polypeptide chains- 2 β globin & 2 α globin

  ~soluble

  ~irregular structure

  ~metabolically reactive

  ~globular protein

  ~highly specific sequence

  ~chain length never varies

  
• Collagen

  ~quaternery structure

  ~no prosthetic group

  ~3 polypeptides make a fibril

  ~ insoluble

  ~repeating structure

  ~metabolically unreactive

  ~fibrous protein

  ~ length of chain can vary

  
• Insulin

  A protein hormone synthesized in the pancreas that regulates blood sugar levels by facilitating the uptake of glucose into tissues
• Amylase

  it is an enzyme that actallises the breakdown of starch in the digestie system
• Keratin

  a fibrous protein forming the main structural constituent of hair, feathers, hoofs, claws, horns, etc. it can be flexible of hard
• Elastin

  found in connective tissue, blood vessles, and skin. it allows tissues to strech and recoil.
• Gene

  sequence of DNA that codes for the primary structure of a protein
• Mutation

  A change in a gene or chromosome that may provide a change in the primary structure of a polypeptide