Proteins Flashcards
(24 cards)
How do monomers form the primary structure of a protein?
Condensation reaction between amino acids; forming peptide bonds; creating a specific sequence/order of amino acids.
What reaction joins amino acids to form a dipeptide?
Condensation (reaction) / loss of water.
What groups form the peptide bond in a dipeptide?
Between amine / NH₂ and carboxyl / COOH.
What determines the structure of a protein?
The (relative) position of amino acid/R group/interactions.
What interactions determine tertiary protein structure?
Hydrogen bonds / disulfide bridges / ionic bonds / hydrophobic-hydrophilic interactions.
What is the primary structure of a protein?
Sequence/order of amino acids.
What forms the secondary structure in a protein?
Hydrogen bonding between amino acids.
What shapes are part of the secondary protein structure?
Alpha helix / β-pleated sheet.
How is tertiary structure formed?
By interactions (between R groups): hydrogen bonds, disulfide bridges, ionic bonds, hydrophobic-hydrophilic interactions.
What does tertiary structure create in enzymes and other proteins?
Active site in enzymes OR complementary/specific shapes in antibodies/carrier proteins/receptors.
What is quaternary protein structure?
More than one polypeptide chain joined by interactions/bonds; may include a prosthetic group.
What are proteins made of?
Polymer of amino acids joined by peptide bonds, formed by condensation reactions.
What is the primary protein structure?
Number AND order of amino acids.
What is the secondary protein structure?
Folding of the polypeptide chain into Alpha-helix and Beta-pleated sheets due to hydrogen bonding.
What is the tertiary protein structure?
3-D folding due to hydrogen bonding, ionic bonding, and disulfide bridges.
What is the quaternary structure of proteins?
Two or more polypeptide chains joined together.
How do you test for proteins in a solution?
Add Biuret solution; purple/lilac result indicates protein is present.
What test confirms the presence of lipid?
Add ethanol/alcohol, then water and shake; white/milky emulsion confirms presence.
How do you confirm a non-reducing sugar is present?
Do Benedict’s test and it stays blue; then boil with acid, neutralise with alkali; heat with Benedict’s → red/orange precipitate forms.
How do you test for amylase in a sample?
Add Biuret reagent → purple/lilac; OR add starch, leave, and test for reducing sugar or starch absence.
How do you distinguish lactase from lactose using the Biuret test?
Add Biuret reagent to both; lactase/enzyme = purple/lilac; lactose = stays blue.
Because: Lactase is a protein.
Why doesn’t sucrase hydrolyse lactose?
Lactose has a different shape/structure; doesn’t fit/bind to sucrase’s active site; no enzyme-substrate complexes formed.
Why doesn’t lactose bind to sucrase?
Active site of sucrase has a specific shape/structure; lactose doesn’t fit = no binding = no reaction.
Draw the general structure of an amino acid
