Proteins Flashcards
What is the monomer of proteins?
amino acids
What elements do proteins contain?
carbon, hydrogen, oxygen, nitrogen
What 2 elements could possibly be found in a protein?
sulphur, phosphorous.
What is the polymer of proteins?
Polypeptide - chain of amino acids
What element is always in a protein?
Nitrogen
What is this group called?
(-NH2)
Amine group
What is this group called?
(-COOH)
Carboxyl group
What is the group that changes in the amino acids called?
Variable R group
What is being defined here?
(A reaction takes place between the amino group of one amino acid and the carboxyl group of another)
Peptide bond
Describe a peptide bond
A reaction takes place between the amino group of one amino acid and the carboxyl group of another
What’s the term for two amino acids bonding?
Dipeptide
What reaction takes place during the bonding of amino acids?
Condensation reaction - a molecule of water is formed
If a condensation reaction occurs in amino acids, what bond is formed?
Peptide bond
Describe the formation of a dipeptide.
Carboxyl group + Amine group –> peptide bond + water molecule
How many protein structures are there, list them.
4 - primary, secondary, tertiary and quaternary
How many types of secondary protein structures are there?
alpha helix,
beta-pleated sheet
Where are the hydrogen bonding in a secondary protein structure?
=O on -CO groups and the -H on -NH groups
Long __________ chain twists into ____ shape
polypeptide, 3D
What is a protein primary structure?
singular peptide chain
What bonds are present in a tertiary protein structure?
Ionic bonds, hydrogen bonds, disulfide bond
A tertiary protein structure: the shape is held in place by hydrogen, ionic and disulfide bonds together with ________________.
hydrophobic interactions
What does a quaternary protein structure consist of?
2 or more tertiary bonded together
Give one example of a quaternary protein structure in the human body
haemoglobin
How many polypeptide chains does haemoglobin consist of?
4
What is the iron-containing group called in the centre of each polypeptide chain in haemoglobin?
Haem
Describe why the maximum number of oxygen molecules each haemoglobin molecule can pick up is four.
Each haem group contains an iron ion (Fe2+). Since each iron ion can bond with one molecule of oxygen, each haemoglobin can pick up four oxygen molecules.
What is the fibrous proteins we must learn?
Collagen
What’s the formation of parallel chain in collagen?
Polypeptides laid down in parallel chains
Describe 3 properties of fibrous proteins.
very stable, insoluble and strong
Describe a collagen fibre - the polypeptide chains and bonds
Three polypeptide chains and each is twisted in the form of alpha-helix. Hydrogen bonds hold three strands in place.
Pair globular proteins/Fibrous proteins with soluble in water/insoluble in water
Globular are soluble in water.
Fibrous are insoluble in water.
globular proteins/Fibrous proteins
stable/not stable
Globular proteins are easily changed chemically therefore not stable.
Fibrous are stable and tough
globular proteins/Fibrous proteins
metabolic functions/structural functions
Globular - metabolic functions.
Fibrous - structural functions
What solution is used to test for the presence of protein and what are the colour change?
Biuret reagent
pale blue to lilac/purple
Describe what is meant by QUALITATIVE
results indicates whether food group is present or not
Describe what is meant by SEMI-QUSNTITATIVE
different colour changes can indicate different concentrations
Describe what is meant by QUANTITATIVE.
actual value for the concentration of food group present
Primary protein structure - what determines the sequence of amino acids?
Base sequence on a strand if the DNA molecule
