PROTEINS Flashcards
amino acids contain
amino group
acid group
General structure of an amino acid
hydrogen
amino central carboxyl acid carbon group
group
R group
How many R groups and amino acids
20
What reaction / bond joins amino acids
peptide bond
condensation reaction
What does a peptide bond look like
O=C-N-H
2 amino acids
Dipeptide
Many amino acids
polypeptide
the beginning and end of a polypeptide chain is called
N terminus - H2N
C terminus - COOH
A sequence of amino acids is based of
The sequence of bases in DNA
Primary structure
The sequence of amino acids in the polypeptide chains which determine the structure
sequence
number and
type
NOT number oreder type
Secondary structure
The structure held together by hydrogen bonds between carboxyl groups and amino acid groups in the polypeptide backbone
These are Alpha helix spirals and Beta [pleated] sheets
Alpha helix
H bonds are formed between non-adjacent amino acids forming into a helix spiral
Alpha helix is very strong and stable structure
What elements in which groups have H bonds between them
The O in the carboxyl group and one of the H in the amino group
Beta [pleated] sheet
polypeptide chains are zigzagged forming a sheet of antiparallel strands held together by hydrogen bonds
Tertiary structure
The compact globular structure is formed by folding a polypeptide chain
They are responsible for the functions and properties of the proteins eg. active sit of the enzyme
How is the tertiary structure held together
By bonds between the R groups of amino acids, so the shape of the protein is dependant on the order of the amino acids and the type of amino acid
What are the 3 bonds that make the globular structure
Weak H bonds
Ionic bonds
Strong Sulphur bridges (covalent S-S bonds between two cysteine amino acids)
What causes inwards and outwards protein folding
Hydrophobic interactions (inward)
Hydrophilic interactions (outward)
Quaternary structure
the interactions and numbers of polypeptide chains in a protein
Examples of quaternary structure
ATP
Hemoglobin
Collagen
Globular and Fibrous proteins
The final 3D shape of a protein
globular protein examples
Most proteins
-enzymes
-membrane proteins
-receptors
-storage proteins
fibrous proteins roles
long and thin usually with structural roles
fibrous proteins examples
-collagen
-keratin
-cytoskeleton
What bonds and structures are broken when an enzyme denatures and what remains
-Secondary,tertiary and quaternary structures are broken due to the breaking of Hydrogen bonds
-Primary structure remains intact along with the covalent bonds and disulphide bridges
What is the biochemical test for proteins
1-Add equal volumes of sodium hydroxide to an aqueous protein sample
2-Add a few drops of aqueous copper sulfate
3-When mixed the solution turns purple when the proteins present
-NaH + H2O
-add CuSO4 + H2O
-purple
