IF WE WERE ABLE TO DETERMINE THE REACTIONS OF THE KREBS’ (TRICARBOXYLIC ACID) CYCLE FROM A WOOLLY MAMMOTH, WOULD YOU EXPECT THEM TO BE:
Totally different from the ones found in humans, but similar to those in elephants
Essentially the same as the ones found in both humans and elephants
Totally different to the ones found in humans and elephants
Similar to those in other extinct mammals, but very different from anything alive today
AN END-PRODUCT CAN ACT TO INHIBIT AN ENZYME BY BINDING AT THE:
Transitional site
Active site
Activation site
Allosteric site
THE SINGLE BIGGEST SIDE-EFFECT OF INSULIN THERAPY IS:
A fear of needles
Hyperactivity
Hypoglycaemia
Hyperglycaemia
WHICH OF THE FOLLOWING IS A COMMON PHYSIOLOGICAL METHOD OF LOWERING BODY TEMPERATURE?
Stimulation of the mitochondria in brown fat cells
Rhythmic Stimulation of skeletal muscle
Increased thyroid gland activity
Accelerated respiration
WHICH OF THE FOLLOWING STATEMENTS CONCERNING ENZYME CASCADES IS FALSE?
They amplify and diversify signals of hormones such as cyclic AMP
They are usually found in the extracellular space
They often involve second messengers
Multiple enzymes undergo conformational change and become activated
WHICH OF THE FOLLOWING STATEMENTS CONCERNING STEROID HORMONES IS TRUE?
They bind to cytoplasmic and/or nuclear proteins to form a hormone receptor complex
They are transcription factors
They bind and activate membrane-bound receptors
They are hydrophilic compounds
THE ENZYME-SUBSTRATE COMPLEX:
Is a key concept that helps to explain how enzymes reduce activation energy for chemical reactions.
Is a key concept that helps to explain how enzymes can reduce the Gibb’s free energy for a chemical reaction.
Is a key concept that helps to explain how enzymes can exhibit diverse substrate specificity.
Is a key concept that helps to explain how enzymes may exhibit Michaelis-Menton kinetics.
CONSIDER AN ENZYME THAT SHOWS MICHAELIS-MENTON ENZYME KINETICS, WHERE: Vo = Vmax . [S] / Km + [S] If a substrate, S, is present at a concentration of 6 mM, and Km is 2 mM, the rate of reaction (Vo) measured will be:
One third of Vmax
Three times Vmax
Three quarters of Vmax
Six times Vmax
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.
THE ENTHALPY CHANGE ASSOCIATED WITH A BIOCHEMICAL REACTION:
Is a term used to describe the amount of randomness or disorder that results as the reaction proceeds
Is a term used to describe the amount of ‘free energy’ change that results as the reaction proceeds
Is a term used to describe the amount of heat that is produced or consumed as the reaction proceeds
Is always determined at room temperature (25oC)
ENZYMES USUALLY UTILISE ONE OR MORE TRANSITION METAL ATOMS AT THE ACTIVE SITE TO:
Facilitate substrate binding
Facilitate transition state formation
Facilitate stabilisation of the tertiary structure
Facilitate conformational changes in the protein during the catalytic cycle
ENZYMES:
Reduce the entropy associated with chemical reactions
Reduce the enthalpy associated with chemical reactions
Reduce the Gibb’s free energy associated with chemical reactions
Reduce the activation energy associated with chemical reactions
THE TRANSITION STATE IN AN ENZYME-CATALYSED REACTION:
Is always covalently associated to the enzyme.
Is never covalently associated to the enzyme.
Can never be observed experimentally.
Can often be similar in structure to potent enzyme inhibitors.
SERINE PROTEASES:
Are proteases that hydrolyse polypeptides with serine in the F1 position
Are proteases that are found in the cytoplasm of all cells
Utilise a serine residue at the active site to facilitate substrate binding
Utilise a serine residue at the active site to facilitate cleavage of peptide bonds
THE UBIQUITIN PROTEIN:
Is only found in eukaryotic cells
Is only found in bacterial cells
Is a key component of the Urea cycle
Is a key component of the Ubiquitin cycle
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.
THE MOST COMMON FORM OF FRUCTOSE IN SOLUTION IS:
A pyranose (six-membered) ring form
A furanose (five-membered) ring form
A straight chain, ketone form
A straight chain, aldehyde form
FATTY ACIDS:
Have a hydrophobic aliphatic carbon chain and a hydrophilic carboxylic acid group
Have a hydrophilic aliphatic carbon chain and a hydrophobic carboxylic acid group
Have a hydrophobic aliphatic carbon chain and a hydrophobic carboxylic acid group
Have a hydrophilic aliphatic carbon chain and a hydrophilic carboxylic acid group
TESTOSTERONE IS:
A sterol
A ketose monosaccharide
A fatty acid
A cofactor
WHICH IF THESE MOLECULES IS COMMONLY INVOLVED IN CELL SIGNALLING AND RIBOSOMAL TRANSLOCATION?
TTP
CTP
UTP
GTP
THE PRECURSORS FOR THE BIOSYNTHESIS OF SUCROSE ARE:
UDP-glucose and fructose 6-phosphate
UDP-fructose and glucose 6-phosphate
UDP-glucose and fructose
UDP-fructose and glucose
TO DETERMINE THE IDENTITIES OF THE COMPOUNDS IN THE CALVIN CYCLE, MELVIN CALVIN USED:
Nuclear magnetic resonance spectroscopy and chemical analysis
Paper chromatography and mass spectrometry
Paper chromatography and chemical analysis
Chemical analysis and mass spectrometry
TRIOSE PHOSPHATE ISOMERASE CATALYSES THE ATTAINMENT OF EQUILIBRIUM BETWEEN THE GLYCOLYTIC INTERMEDIATES GLYCERALDEHYDE 3-PHOSPHATE AND DIHYDROXYACETONE PHOSPHATE. UNDER THE CONDITIONS PREVAILING IN A HUMAN CELL, ON WHICH SIDE DOES THE EQUILIBRIUM LIE?
It is not possible to know this from the information provided
Dihydroxyacetone phosphate
The equilibrium is approximately equally balanced
Glyceraldehyde 3-phosphate
CONSIDER TWO REACTIONS. REACTION 1 HAS A ΔG°′ VALUE OF -20 kJ.mol-1 AND REACTION 2 HAS A ΔG°′ VALUE OF -50 kJ.mol-1. WHICH REACTION PROCEEDS AT THE FASTEST RATE AT ROOM TEMPERATURE AND PRESSURE AND pH 7?
Reaction 1
Reaction 2
They both occur at much the same rate
It is not possible to know this from the data provided
IN GLYCOLYSIS, THE CONVERSION OF PHOSPHOENOLPYRUVATE TO PYRUVATE IS COUPLED TO:
The phosphorylation of ADP to make ATP
The phosphorylation of GDP to make GTP
The reduction of NAD+ to make NADH
The oxidation of NADPH to make NADP+
IN YEAST UNDER ANAEROBIC CONDITIONS, ETHANOL IS PRODUCED AT THE END OF THE GLYCOLYTIC PATHWAY. WHY IS THIS ADVANTAGEOUS TO THE YEAST?
It enables the regeneration of NAD+
It enables it to produce more NADH
A molecule of ATP can be produced from the reaction
It helps the brewing industry
UNDER ANAEROBIC CONDITIONS IN HUMANS, HOW MANY MOLECULES OF CARBON DIOXIDE (CO2) ARE PRODUCED BY THE METABOLISM OF ONE MOLECULE OF GLUCOSE BY GLYCOLYSIS AND SUBSEQUENT PATHWAYS?
6
4
2
0
LACTOSE IS A DISACCHARIDE OF:
Glucose and mannose
Mannose and fructose
Galactose and fructose
Glucose and galactose
THE COFACTOR FAD (FLAVIN ADENINE DINUCLEOTIDE) IS COMPOSED OF WHICH SUBUNITS?
Flavin, ribose, adenine and three phosphates
Flavin, two riboses, two adenines and a phosphate
Flavin, two riboses, two adenines and two phosphates
Flavin, ribose, adenine and two phosphates
NADPH IS USED IN THE CALVIN CYCLE TO:
Oxidise 1,3-bisphosphoglycerate
Reduce 1,3-bisphosphoglycerate
Oxidise ribulose 1,5-bisphosphate
Reduce ribulose 1,5-bisphosphate
IN GLUCONEOGENESIS, THE CORRECT SEQUENCE OF COMPOUNDS IN THE CONVERSION OF PYRUVATE TO PHOSPHOENOLPYRUVATE IS:
Pyruvate → Oxaloacetate → Phosphoenolpyruvate
Pyruvate → Lactate → Phosphoenolpyruvate
Pyruvate → Succinate → Phosphoenolpyruvate
Pyruvate → 1,3-bisphosphoglycerate → Phosphoenolpyruvate
THE INCREASE IN ATP LEVELS THAT ACCOMPANIES THE "PASTEUR EFFECT" CAUSES:
decreased glycolytic flux by allosteric stimulation of lactate dehydrogenase
allosteric inhibition of fructose 1,6-bisphosphatase
allosteric inhibition of phosphofructokinase-1
increased glycolytic flux by allosteric activation of phosphofructokinase-2
GLYCOGEN PHOSPHORYLASE IS:
inhibited by phosphorylation
activated by phosphorylation
activated by glucose
inhibited by AMP
PROTEIN KINASE A:
is an allosteric enzyme
phosphorylates phosphorylase kinase
phosphorylates glycogen phosphorylase
is activated by ADP
ADRENALINE:
induces glycogen synthesis in the liver
induces gluconeogenesis in the liver
accelerates glyconeogenesis in the heart
inhibits glycolysis in the heart
GLYCOGEN PHOSPHORYLASE KINASE
is activated by cAMP
is activated by dephosphorylation
is activated by autophosphorylation
is activated by protein kinase A
WHAT IS THE SOURCE OF ENERGY FOR ATP SYNTHESIS IN MITOCHONDRIA?
ADP and inorganic phosphate
Gradient of NADH across the inner mitochondrial membrane
Matrix aconitase
None of the above
WHAT IS THE OVERALL EQUATION FOR PHOTOSYNTHESIS?
18 CO2+ 2 NADPH + 3 ATP + light → 2 NADPH + 3 Glucose-1-phosphate + 3 ADP + 18 O2
2 H2O + 2 NADP+ + 3 ADP + 3 Pi + light → 2 NADPH + 2 H+ + 3 ATP + O2
2 H2O + 2 NAD+ 2 Pi → 2 NADPH + 2 H+ + O2 + light
CO2 + light + H2O → Glucose + O2
WHICH OF THE FOLLOWING IS NOT A REDOX CENTRE FOR RESPIRATORY CHAIN?
NADH
Cytochrome c
Oxygen
FADH2
THE OXYGEN MOLECULES RELEASED INTO THE AIR AS A PRODUCT OF PHOTOSYNTHESIS COMES FROM:
Light quanta
Cytochome c oxidase
Water
Carbon dioxide
