WHICH OF THESE LISTS CONTAINS ONLY MONOSACCHARIDES?
Glucose, galactose, fructose
Sucrose, lactose, mannose
Glucose, galactose, lactose
Glucose, galactose, sucrose
STARCH IS SYNTHESISED BY:
Plants
Insects
Cancer cells
All of the above
WHICH FUNCTIONAL GROUPS ARE PRESENT IN THE STRAIGHT CHAIN FORM OF FRUCTOSE?
Aldehyde and amine
Amine and ketone
Ketone and alcohol
Amine and alcohol
FOR EACH MOLECULE OF GLUCOSE, WHAT IS THE NET GAIN OF ATP IN GLYCOLYSIS?
No molecules
2 molecules
4 molecules
8 molecules
A DISEASE IS CAUSED BY MUTATIONS IN THE GENES ENCODING ENZYMES IN THE LELOIR PATHWAY. WHICH SUGAR WILL PATIENTS BE UNABLE TO METABOLISE?
Glucose
Galactose
Fructose
Mannose
PERIPHERAL MEMBRANE PROTEINS ARE:
Associated with integral membrane proteins
Covalently linked to lipid molecules
Always glycosylated
Inserted into the membrane such that they have residues exposed on both sides
THE STRUCTURE AND FUNCTION OF A METABOLIC ENZYME IS LIKELY TO BE:
Very different, even in closely related organisms
Similar in different mammals, but different between mammals and the bacteria living in their guts
Similar in all animals, but different in plants
Highly conserved through evolution by natural selection
THE CALVIN CYCLE (“DARK” REACTIONS OF PHOTOSYNTHESIS):
Uses sucrose and NADPH
Generates sucrose and NADPH
Uses sucrose and generates NADPH
Generates sucrose and uses NADPH
A SATURATED FATTY ACID WITH 18 CARBONS WILL BE OXIDISED BY β-OXIDATION TO GIVE:
18 molecules of CoA
18 molecules of acetyl-CoA
9 molecules of CoA
9 molecules of acetyl-CoA
WHICH OF THESE FATTY ACIDS IS LIKELY TO HAVE THE LOWEST MELTING TEMPERATURE?
An 18 carbon saturated fatty acid
An 18 carbon fatty acid with one double bond
A 16 carbon saturated fatty acid
A 16 carbon fatty acid with two double bonds
THE SUGAR RESIDUE IN ATP IS:
Ribose
Deoxyribose
Ribulose
Raffinose
THE CONVERSION OF GLYCERALDEHYDE 3-PHOSPHATE TO 1,3-BISPHOSPHOGLYCERATE IN GLYCOLYSIS REQUIRES:
ATP and NAD+
Inorganic phosphate ions (Pi) and NADH
Inorganic phosphate ions (Pi) and NAD+
ATP and NADH
IN MAMMALIAN CELLS UNDER ANAEROBIC CONDITIONS, THE CONVERSION OF PYRUVATE TO LACTATE REGENERATES WHICH MOLECULE?
NADH
NAD+
FAD
ATP
CONSIDER GLYCOLYSIS AND THE KREBS’ TRICARBOXYLIC ACID CYCLE TOGETHER. WHICH IS THE FIRST STEP WHICH RELEASES CARBON DIOXIDE?
Fructose 1,6-bisphosphate → Glyceraldehyde 3-phosphate + dihydroxyacetone phosphate
Pyruvate → Acetyl Coenzyme A
Citrate → Isocitrate
Isocitrate → α-ketoglutarate
THE DECARBOXYLATION OF ISOCITRATE TO PRODUCE α-KETOGLUTARATE IN THE KREBS’ TRICARBOXYLIC ACID CYCLE REQUIRES:
NADP+
NADPH
THE SEQUENCE OF REACTIONS OXIDATION-HYDRATION-OXIDATION OCCURS IN WHICH TWO METABOLIC PATHWAYS?
Glycolysis and the Krebs’ tricarboxylic acid cycle
Fatty acid oxidation and glycolysis
Fatty acid oxidation and the Krebs’ tricarboxylic acid cycle
Fatty acid oxidation and the Leloir pathway
THE REACTION: PYRUVATE + CARBON DIOXIDE + ATP → OXALOACETATE + ADP + PI, WHICH IS CATALYSED BY THE ENZYME PYRUVATE CARBOXYLASE IS IMPORTANT IN WHICH TWO PROCESSES?
Replenishing the Krebs tricarboxylic acid cycle intermediates and gluconeogenesis
Glycolysis and gluconeogenesis
Gluconeogenesis and glycogen synthesis
Replenishing the Krebs tricarboxylic acid cycle intermediates and glycolysis
IN BIOCHEMICAL PATHWAYS THE PRECURSORS ARE:
Compounds which occur at cross-over or branching points in metabolic pathways
Initial substrates which feed into metabolic pathways
Compounds which catalyse the individual steps in a metabolic pathway
Metabolic hubs which allow the use and re-use of relatively small numbers of molecules
PROTEIN BIOSYNTHESIS CYCLE IS AN EXAMPLE OF WHICH TYPE OF BIOCHEMICAL PATHWAY?
Anabolic
Catabolic
Amphibolic
Hyperbolic
WHICH OF THE FOLLOWING IS TRUE OF ENDOTHERMS?
They generate most of their heat through internal processes
They get most of their heat from the environment
They generate most of their heat from external processes
They cannot regulate their body temperature
PARATHYROID HORMONE HELPS REGULATE:
Body fluids
Blood calcium
Body temperature
Breathing
A COMMON MECHANISM FOR INHIBITING METABOLIC PATHWAYS IS:
A build up of substrates
A build up of end-products
Over-activation of enzymes
Synthesis of new enzymes
FRUCTOSE 2,6-BISPHOSPHATE:
Activates fructose bisphosphatase-1
Activates phosphofructokinase-1
Inhibits phosphofructokinase-2
Activates phosphofructokinase-2
ANAEROBIC MUSCLE CELLS PRODUCE LACTIC ACID TO RECYCLE:
NADH to NAD+ via the action of lactate dehydrogenase
NADH to NAD+ via the action of alcohol dehydrogenase
NAD+ to NADH via the action of lactate dehydrogenase
NAD+ to NADH via the action of alcohol dehydrogenase
OXYGENATION OF ANAEROBIC YEAST CULTURE INDUCES THE "PASTEUR EFFECT", WHICH IS CAUSED BY:
Allosteric inhibition of phosphofructokinase-1 by increased AMP levels
Allosteric inhibition of fructose 1,6-bisphosphatase by increased ATP levels
Allosteric inhibition of phosphofructokinase-1 by increased ATP levels
Allosteric stimulation of phosphofructokinase-1 by increased AMP levels
CYCLIC AMP IS:
An activator of pyruvate kinase
An activator of protein kinase A
The product of adenylate kinase
An activator of phosphofructokinase-1
CANCER CELLS PRODUCE LARGE AMOUNTS OF LACTATE EVEN IN THE PRESENCE OF OXYGEN BECAUSE THEY:
Lack mitochondria
Lack the gene for citrate synthase
Possess an over-active glycerol phosphate shuttle
Have a defective glycerol phosphate shuttle
WHEN CONSIDERING ENZYME CATALYTIC MECHANISMS, ACID-BASE CATALYSIS IS USUALLY DEPENDANT UPON:
Hydrogen bonding with at least one amino acid side chain at the active site to facilitate formation of the transition state.
Hydrogen bonding between the carbonyl and amide groups of peptide bonds to facilitate formation of the transition state.
Hydrogen bonding between a water molecule and the substrate to facilitate formation of the transition state.
Hydrogen bonding with an oxidised metal ion prosthetic group in the active site to facilitate formation of the transition state.
MULTIPLICATION OF UBIQUITIN TAGGING:
Inhibits proteosome-mediated protein degradation
Is essential for proteosome-mediated protein degradation
Enhances proteosome-mediated protein degradation
Has nothing to do with proteosome-mediated protein degradation
ENZYMES REDUCE THE:
Entropy associated with chemical reactions
Enthalpy associated with chemical reactions
Gibb’s free energy associated with chemical reactions
Activation energy associated with chemical reactions
THE TRANSITION STATE IN AN ENZYME-CATALYSED REACTION:
Is always covalently associated with the enzyme.
Is never covalently associated with the enzyme.
Can never be observed experimentally.
Can often be similar in structure to potent enzyme inhibitors.
THE ALANINE CYCLE:
Is completely located in the mitochondrial matrix.
Facilitates transport of ammonia produced in the liver to the muscles where it can be used in anabolic processes - preventing the exposure of free ammonium to other components of eukaryote tissues.
Facilitates transport of ammonia produced in the muscles to the liver where it can be effectively removed from the body - preventing the exposure of free ammonium to other components of eukaryote tissues.
Is completely located in the cytoplasm of the cell – preventing the exposure of free ammonium to other components of eukaryote tissues.
KOSHLAND’S INDUCED FIT MODEL FOR ENZYME-SUBSTRATE COMPLEX FORMATION MAY EXPLAIN WHY:
Enzymes have particular substrate specificity.
Enzymes are able to catalyse chemical reactions that cannot be facilitated in any other way
Enzymes increase the rate of a reaction by reduction of the activation energy change for the reaction
Enzymes can effectively reduce the loss of energy from a chemical reaction as heat
IN ENZYME CATALYSIS THE TERM “APPROXIMATION” REFERS TO:
A catalytic strategy that facilitates transition state stabilisation through formation of covalent bonds between a substrate and amino acid groups in the active site
A catalytic strategy that facilitates transition state stabilisation through formation of hydrogen bonds and electrostatic interactions between a substrate and amino acid groups in the active site
A catalytic strategy that facilitates transition state stabilisation through interaction with metal ions in the active site
A catalytic strategy that facilitates transition state stabilisation through direct transfer of a proton to the substrate from an acidic amino acid group in the active site
AN OXYANION HOLE IS:
A region of the enzyme active site that facilitates binding of positively charged substrates through their association with oxygen-containing amino-acid side chains in the enzyme.
A region of the enzyme active site that facilitates binding of negatively charged substrates through their association with oxygen-containing amino-acid side chains in the enzyme.
A region of the active site that facilitates binding of positively charged oxygen-containing groups present in a substrate.
A region of the active site that facilitates binding of negatively charged oxygen-containing groups present in a substrate.
IF THE ΔG°' OF THE REACTION A → B is –20 kJ/mol, WHAT WILL HAPPEN IN THE PRESENCE OF A SPECIFIC ENZYME UNDER STANDARD CONDITIONS?
The reaction will stop
The reaction will proceed spontaneously from B to A
The reaction will proceed spontaneously from A to B
The reaction will not occur spontaneously
WHICH OF THE FOLLOWING IS AN EXERGONIC PROCESS?
Biosynthesis of DNA
Glycolysis
Transport of protons by respiratory chain
Brain activity due to the thinking about this question
FOR THE FOLLOWING REACTION: L-Malate + NAD+ → Oxaloacetate + NADH + H+ ΔG°' = +29.7 kJ/mol. WHICH OF THE FOLLOWING STATEMENTS IS CORRECT?
This reaction can only occur in a cell in which NADH is converted to NAD+ by the respiratory chain
This reaction can only occur in a cell if it is coupled to another reaction for which ΔG°' is large and negative
This reaction may occur in cells at some concentrations of substrate and product
This reaction is energy-releasing
WHICH OF THE FOLLOWING STATEMENTS ABOUT MIDPOINT REDOX POTENTIALS IS INCORRECT?
Redox potentials can be used to calculate free energy changes
Redox potential is measured in volts
Oxygen reduction has the highest potential
The strongest oxidants have the most negative potential
WHICH OF THE FOLLOWING REDOX COUPLE HAVE THE HIGHEST MIDPOINT REDOX POTENTIAL?
Plastoquinol/plastoquinone
NADH/NAD+
H2O/½O2
Ferrocytochrome c/ferricytochrome c
