proteins Flashcards
what are the monomers of proteins
amino acids
what is a dipeptide
two amino acids joined together
what is a polypeptide
more than two amino acids joined together
what are proteins made up of
one or more polypeptides
what is in the basic structure of amino acids
- carboxyl group
- amine group
-R group (variable side group)
how many different amino acids do all living things share
20
what makes amino acids different
what makes up their R group
what reaction forms polypeptides
condensation reactions
what is the bond between two amino acids
peptide bond
primary structure of proteins
the sequence of amino acids in the polypeptide chain
secondary structure of proteins
polypeptide chain does not remain flat and straight
- hydrogen bonds form between amino acids in the chain
- makes it automatically coil into alpha helix or beta pleated sheets
tertiary structure of proteins
- chains of amino acids coiled and folded further
- more bonds form between different parts of the polypeptide chain including hydrogen and ionic bonds.
-disulfide bridges form whenever two molecules of the cysteine come close together (sulfur atoms in each cysteine) - for proteins made from a single polypeptide chain, tertiary structure forms their final 3d structure
quarternary structure of proteins
- some proteins are made of several different polypeptide chains held together by bonds
- the quarternary structure is the way these polypeptide chains are assembled together
- for proteins with more than 1 polypeptide chain, this forms the final 3d structure (haemoglobin, insulin, collagen)
structure of enzymes
roughly spherical in shape due to the tight folding of polypeptide chains
- soluble and often used in roles in metabolism
- some break down molecules and some help synthesise large molecules
structure of antibodies
- involved in immune response
- made up of two light (short) polypeptide chains and two long (heavy) polypeptide chains bonded together
- antibodies have variable regions, the amino acid sequences in these regions vary greatly
Transport proteins structure
- channel proteins in cell membranes (e.g.)
- channel proteins contain hydrophobic and hydrophillic amino acids which cause the protein to fold up and form a channel
- these proteins transport molecules and ions across membranes
structural proteins structure
- physically strong
- consist of long polypeptide chains lying parallel to eachother with cross links between them
- structural proteins include keratin (found in hair and nails)
where is collagen found
connective tissue
where is keratin found
nails and hair
buiret test for proteins
- add a few drops of sodium hydroxide solution to make the solution alkaline
- add copper sulphate solution
- if protein is present the solution will turn purple
- if there is no protein the solution will stay blue
