proteins Flashcards
what are the monomers for protein
amino acids
all proteins contain which elements
-nitrogen
-carbon
-hydrogen
-oxygen
some contain sulfur
why do proteins have a specific role
because each protein has a specific shape
amino acids can link together in a chain of peptide bonds to form…
a polypeptide
what bond links/binds together amino acids
peptide bond
how many different types of amino acids are there
20, and they all have the same general formula
what is the general formula for an amino acid
R-CH(NH2)-COOH
H R O
I I II
N - C - C
I I I
H H OH
give the structure of an amino acid
-each amino acid contains a central alpha carbon to which a nitrogen containing amine group (H2N) and a carboxyl group (COOH) are attached
-the R group indicates the variable group (20 different options)
R groups can be….
-positively charged
-negatively charged
-hydrophilic attracted to water
-hydrophobic repelled by water
how is a peptide bond formed
the hydroxyl group from one amino acid combines with a hydrogen atom from the amino group in the second amino acid to form a water molecule which is removes and a bond is formed
what is formed when two amino acids join together
dipeptide
if there is 10 amino acids present how many peptide bonds are there
9, always one less than number of amino acids
what is a protein
a polymer made up of the monomers amino acids- chain of amino acids
what is the primary structure
-number and sequence and order of amino acids in a polypeptide chain
-proteins are different from each other because their primary structures, amino acids sequence and numbers are different.
what is the secondary structure
-it is a 2D shape
- polypeptide folds into alpha helixes or/and beta pleated sheets
- held together by many weak hydrogen bonds between the C=O groups of the carboxyl group of one amino acid and H in the amine group of another
what is the tertiary structure
-further folding of secondary structure/polypeptide chain into a specific unique 3D shape
-the R groups on the amino acids in polypeptide chain determine how the chain folds into it’s specific 3D shape
why is the tertiary structure essential to a protein’s function
- the shape of protein determines how it interacts with other molecules which is necessary for it to carry out its specific function
what is the quaternary structure
-protein is made up of two or more polypeptide chains joined together
-sometimes there may be a prosthetic group (non-protein component) in a protein
-haemoglobin is an example and its a globular protein
what are globular proteins
-they are functional proteins
-approx spherical shape
-soluble in water because globular proteins have got hydrophilic amino acids on their surface so that the hydrophilic R groups can interact with water molecules
-they are transport proteins such as haemoglobin, lipase,DNA polymerase and insulin
give examples of globular proteins
-they are transport proteins such as haemoglobin, lipase,DNA polymerase and insulin
what are fibrous proteins
-are structural proteins
-often play a structural role for example in bones or tendons or in the walls of blood vessels such as arteries
-fibrous proteins tend to form long rope-like molecules and 3 alpha helixes
-they have a large proportion of amino acids with hydrophobic R groups therefore they are insoluble in water
-they are tough and strong
give 3 examples of fibrous proteins
collagen
keratin
elastin
why are antibodies only effective against a specific pathogen
-antigens on pathogens have a specific shape/3D structure
-antibodies are complementary to the antigen so they bind to it and form antibody-antigen complex
when do proteins denature
only at high temps and large changes to pH
