Mock Revision Topic 1 Flashcards
Biological Molecules + Enzymes
What is a monomer?
Smaller units from which larger molecules are made.
What is a polymer?
Molecules made from a large number of monomers joined together.
Name 3 examples of monomers and their
polymer.
- Monosaccharides e.g. alpha glucose – polymer
glycogen and starch, beta glucose – polymer cellulose - Amino acids – polypeptide/protein
- Nucleotides - DNA/RNA
What is a condensation reaction?
Joins two molecules together with the formation of a chemical bond and involves the elimination of a molecule of water.
What is a hydrolysis reaction?
Breaks a chemical bond between two molecules and involves the use of a water molecule.
When 2 monosaccharides join, name the
reaction and the type of bond formed.
Condensation and glycosidic bond.
Name 3 disaccharides and their constituent
monomers. For all state which are reducing
and which are non-reducing sugars.
Maltose (reducing sugar) = Glucose and Glucose
Lactose (reducing sugar) = Glucose and Galactose
Sucrose (non-reducing sugar) = Glucose and Fructose
Draw α and β glucose.
a - H O H
HO OH
b - H O OH
HO O H
Name 3 polysaccharides; for each which type
of organism are they found in and name the
monomer.
Plants: Starch – alpha glucose
Cellulose – beta glucose
Animals: Glycogen – alpha glucose
Describe the biochemical test for:
a) Reducing sugar
b) Non-reducing sugar
c) Starch
for each name the reagent and make clear
what a positive and negative result is.
Reducing sugar:
1. Heat with Benedict’s solution
2. Brick red precipitate = reducing sugar present
3. Blue = no reducing sugar
Non-Reducing sugar:
1. Heat with Benedict’s solution to confirm a negative result (Blue)
2. Heat a new sample with acid
3. Cool and neutralise with alkali
4. Heat with Benedict’s solution
5. Brick red precipitate = Non-reducing sugar present
6. Blue – No non-reducing sugar present
Starch:
1. Add iodine solution to a sample
2. Blue/Black = Starch present
3. Yellow = No starch present
What reaction forms a triglyceride, what is it
made up of and name the type of bond
formed.
Glycerol and 3 fatty acids
Condensation reaction
Ester bond
What is the difference between a
saturated/unsaturated fatty acid?
Saturated fatty acid – no double bonds between carbon atoms in the hydrocarbon chain.
Unsaturated fatty acid – one or more double bonds between carbon atoms in the hydrocarbon chain
How does a phospholipid differ from a
triglyceride?
Phospholipid has a phosphate group and two fatty acids
attached to glycerol whereas a triglyceride has three
fatty acids attached to glycerol
Describe the emulsion test for lipids and the
positive and negative result (3)
Add ethanol, shake/mix to dissolve any lipids then add
water
White emulsion = lipid present
Colourless = no lipid present
Draw an amino acid
R
H2N C COOH
H
How is a dipeptide formed? - name the bond,
exactly which groups the bond forms between
and the type of reaction.
Two amino acids join by a condensation reaction and a
peptide bond is formed.
Describe each level of structure in a protein -
name the bonds involved at each level
Primary structure – sequence of amino acids joined by
peptide bonds in a polypeptide
Secondary structure - polypeptide chain can coil/fold to
form a beta pleated sheet or an alpha helix. Hydrogen
bonds are present
Tertiary structure – further folding and coiling of the
secondary structure. Hydrogen, ionic and
(maybe) disulphide bonds
Quaternary protein – made from more than one
polypeptide chain. Hydrogen, ionic, disulphide bonds,
hydrophobic interactions
Describe the test for a protein - include the
name of the reagent and what a positive and
negative result look like.
Add Biuret reagent to the sample
Purple = Protein is present
Blue = No protein present
Which type of energy does an enzyme lower?
Activation energy
What is the induced fit model? (2)
- This suggests that the active site of an enzyme is
flexible and can slightly change its shape - When the substrate binds to the active site, this
causes the active site to change in shape and become
complementary to the shape of the substrate
What is a non-competitive inhibitor? (5)
- Not similar in shape to the substrate
- Binds at a position on the enzyme away from the active
site (allosteric site) - Changes the shape (tertiary structure) of the active site
- Active site is no longer complementary to the substrate
- Substrate unable to bind to the enzyme to form and
enzyme-substrate complex
What is a competitive inhibitor? (4)
- Similar shape to the substrate
- Binds to the active site
- Prevents the substrate binding to the active site
- Fewer enzyme-substrate complexes are formed
In an experiment how would you show
whether an inhibitor is competitive or non-
competitive? (4)
- Add more substrate
- If the rate of reaction increases to the maximum = competitive inhibitor.
- If it remains below the maximum = non-competitive inhibitor
- The effects of a competitive inhibitor can be overcome
by the addition of more substrate
What does DNA stand for?
Deoxyribonucleic acid
