Aerobic Respiration Flashcards
1) SCENARIO:
Trevor is a diabetic and has checked his blood glucose levels which have indicated he is hyperglycaemic. Which glucose transporter will detect this?
A- GLUT 1 B- GLUT 2 C- GLUT 3 D- GLUT 4 E- GLUT 5
B
EXPLANATION:
GLUT 2 – glucose sensor which would stimulate insulin secretion to reduce Trevor’s glucose levels
1) SCENARIO:
Andrew is revising the steps of glycolysis but cannot remember which key regulatory enzyme is inhibited by alanine. Can you help him?
A- Glucokinase B- Hexokinase C- Phosphofructokinase-1 D- Phosphofructokinase-2 E- Pyruvate kinase
E
EXPLANATION:
Pyruvate kinase is inhibited by alanine
- also inhibited ATP, but is upregulated by fructose 2,6 – bisphosphate
WHY NOT?
Option B – inhibited by its product
Option C – inhibited by ATP, citrate and pH
Option D – involved in substrate cycle
1) SCENARIO:
Unfortunately, Jeff has a rare mitochondrial condition known as lipoic acid synthetase deficiency. Which stage of aerobic respiration would this condition have the most effect on?
A- Citric acid cycle B- Fermentation C- Glycolysis D- Link Reaction E- Oxidative phosphorylation
D
EXPLANATION: Link reaction – lipoic acid is a cofactor of pyruvate dehydrogenase
other co-factors: TPP, NAD, FAD, CoA
SCENARIO:
John was studying for his F1 exam and came across Rate limiting step, he wanted to know what step in Glycolysis Is the rate limiting step?
Which answer is correct?
A –Phosphophenyl Pyruvate to Pyruvate
B- F1,6bisphosphate to GAP & DHAP
C- Fructose 6 phosphate to Fructose 1,6 bisphosphate
D- GAP to 1,3bisphosphoglycerate
C
EXPLANATION: Addition of the phosphate group and allosteric inhibition
SCENARIO: What is Na/K+ transporter an example of?
A –Antiport
B- Symport
C- Uniport
A
EXPLANATION: Both molecules moving in the opposite direction.
SCENARIO: Tim wanted to know what enzyme group is responsible for causing the splitting of 2 molecules into 1.
A –Transferase B- Isomerase C- Hydrolase D- Lyase E- Ligase
D
EXPLANATION:
Break molecules without the addition of water.
If question mentioned water then would be hydrolase
1.)Which of the following chemical reaction is amphibolic (both catabolic and anabolic)?
A- Glycolysis
B- Link reaction
C- Kreb cycle
D- Oxidative phosphorylation
C
Respiration is mainly composed of catabolic pathway , where the substrates molecules are undergoes a series redox and degradation into smaller molecules
Kreb cycle is only catabolic and anabolic.
2.) Uncouplers protein ,UCP ,are weak acids, which prevent mitochondria from establishing a proton gradient across its inner membrane. In the 19th century some European women (and possibly men!) used UCP as a weight-loss treatment. Which single effect is most likely to be caused by long-term treatment with an UCP ?
A- Accumulation of reduced coenzymes (NADH, FADH 2 )
B- Destruction of the inner mitochondrial membrane
C- Excessive heat production (thermogenesis)
D- Increased mitochondrial ATP synthesis
E- Inhibition of the mitochondrial electron transport chain
C- Excessive Heat Production
This production of ATP is called oxidative phosphorylation. Weak acids, like uncouplers, transfer protons through the lipid bilayer of
the inner membrane, thereby abolishing the proton gradient and making ATP synthesis impossible. The energy of oxidative
metabolism is thus lost as heat, and in the process weight gain is minimized. Uncouplers do not interfere directly with the accumulation of
reduced coenzymes (A) and do not affect the structural integrity of mitochondrial membranes (B). Uncouplers reduce, and do not
increase, ATP synthesis (D) and uncouplers do not inhibit the electron transport chain (E), responsible for pumping protons out of
the mitochondrion. Physiologically, the controlled uncoupling of mitochondria occurs in the cells of brown adipose tissue in neonates, in order to generate
heat for the maintenance of body temperature.
3.)Many metabolically important coenzymes are derivatives of vitamins of the B group. Dietary deficiency of such vitamins causes metabolic disease. Which single coenzyme, derived from Vitamin B6, is essential in most metabolic reactions of amino acids?
A- Biotin
B- Flavin adenine dinucleotide (FAD)
C- Nicotinamide adenine dinucleotide (NAD)
D- Pyridoxal phosphate
E- Thiamine pyrophosphate
D- Pyridoxal phosphate
Many reactions of amino acids entail the transfer of their α –amino group, leaving behind their carbon skeleton. Such amino group
transfer requires the coenzyme pyridoxal phosphate, derived from dietary vitamin B 6 (mixture of pyridoxine –alcohol + pyridoxal –aldehyde.) Hence the VitaB6 dietary requirement increase with protein intake. This enzyme is also involved in neurotransmitter 5HT / noadrenline . Sphingosine .
Biotin (A) – ‘VitaB7 ‘ is essential for carboxylation reactions, synthesised in intestinal flora (storage) lipogenesis , gluconeogenesis and catabolism of branched –chain amino acid. Riboflavin and niacin give rise to redox coenzymes such as FAD (B) and NAD (C), respectively. Thiamine (E) in its pyrophosphate form is an important
coenzyme in reactions involving acyl group transfer – carbohydrate metabolism e.g. PDH ,oxidative decarboxylation of a-ketoglutarate & pentose pathway & HCl production. = deficiency = beri beri syndrome .
VitaB5 panthotentic acid = CoA
A subject performs a moderate exercise test on a treadmill for 10 minutes. Their resting RER was 0.8 and increased to 0.95 at the end of the test. Calculate the the ratio of glucose:fat used as fuel before and after.
Rg + Rf = 1
RER = Rg + (0.7 x Rf)
Hint make in terms of Rf (so Rg = 1-Rf)
Before:
RER = Rg + (0.7 x Rf) 0.8= Rg + (0.7xRf) Using Rg = 1- Rf 0.8 = 1-Rf +0.7Rf Rf-0.7Rf = 1-0.8 0.3Rf = 0.2 Rf = 2/3 Thus Rg =1/3 (Using Rg + Rf = 1 )
Ratio is 1:2
After:
RER = Rg + (0.7 x Rf) 0.95= Rg + (0.7xRf) Using Rg = 1- Rf 0.95 = 1-Rf +0.7Rf Rf-0.7Rf = 1-0.95 0.3Rf = 0.05 Rf = 1/6 Thus Rg =5/6 (Using Rg + Rf = 1)
Ratio is 5:1
Which steps of the Glycolysis are reversible (regulatory) and what are the enzymes involved?
a) Step 1 (Hexokinase), Step 3 (PFK1) and Step 10 (Pyruvate Kinase)
b) Step 1 (Hexokinase), Step 2 (PFK2) and Step 10 (PFK1)
c) Step 1 (Hexokinase), Step 3 (PFK2) and Step 10 (Glucokinase)
d) Step 2 (Hexokinase), Step 3 (PFK1) and Step 10 (PFK2)
e) Step 2 (Glucokinase), Step 2 (Pyruvate kinase) and Step 10 (PFK1)
A
Some cells that do not have mitochondria (red blood cells) or they do anaerobic respiration (oxygen debt), they produce lactate. Through which cycle is lactate recycled into pyruvate.
a) Kreb cycle
b) Cori cycle
c) Calvin cycle
d) Alanine cycle
e) TCA cycle
B- Cori Cycle
Gluconeogenesis happens primarily in which organs?
a) Liver and Pancreas
b) Liver and Heart
c) Pancreas and Cortex of Kidney
d) Muscle and Intestines
e) Liver and Cortex of Kidney
E- Liver and cortex of Kidney
In skeletal muscle cells (need quick supply of energy) , the NADH molecules produced in glycolysis must be transported onto the electron transport chain (inner membrane of mitochondria) under aerobic conditions. To do this, these cells utilize which shuttle?
a) Malate Aspartate
b) Glycerate-3-phosphate
c) ATP-ADP Trasnlocase
d) Ornithine
e) Citrate
B- Glycerate-3-phosphate
Which of the following complexes of the electron transport chain do the electrons from FADH2 miss?
a) Complex 1
b) Complex 2
c) Complex 3
d) Complex 4
e) Complex 5
A- Complex 1
