1.6 Proteins Flashcards
monomer of proteins:
amino acids
structure of amino acids;
C +
- amino group (basic)
- carboxyl group (acidic)
- r-group (unique to each a/a)
bonds between amino acids:
peptide bond
primary structure of proteins:
is the sequence of a/a in a polypeptide chain
- determined by the sequence of bases in gene
- determines the shape of the protein, therefore also its function
protein shapes specificity:
are very specific, any changes to the primary structure can change the proteins shape/function
secondary structure of proteins:
+ bond
when the polypeptide chain twist/coils into a alpha helix
or
when it folds into beta pleated sheets
held together by hydrogen bonds between the amino group of one a/a and the carboxyl group of another
tertiary structure of proteins:
+ bonds
when the alpha helix and the beta pleated sheets further coil and form a 3D specific shape held by ;
- hydrogen bonds (weak)
- ionic bonds
- disulfide bonds (strong)
how are the hydrogen bonds in the tertiary structure of proteins made?
formed between +ve H on amino group and -ve O on the carboxyl group
how are the ionic bonds in the tertiary structure of proteins made?
between +ve and -ve charges on amino/carboxyl groups in R-groups
how are the disulfide bonds in the tertiary structure of proteins made?
form between 2 cysteine a/a
quaternary structure of proteins:
+ examples
formed from multiple polypeptide chains joined together
can have non-protein groups associated with the protein
e.g/ antibodies, haemoglobin, insulin
e.g/ haemoglobin is linked to an iron group
Test for proteins:
- add equal volumes of sample and NaOH solution at room temp
- add a few drops of very dilute copper (II) sulfate solution and mix gently
+ve result: purple (peptide bonds present)
-ve result: blue (no proteins present)
