LM10 Flashcards
Which molecules act as stores of energy and reducing power during catabolism?
Enzyme inhibitors
Protein kinases
Coenzymes such as NADH
Enzymes such as glyceraldehyde 3-phosphate dehydrogenase
c
When oxygen is present, which of the following metabolic reactions occurs first after glycolysis?
Conversion of pyruvate into lactate
Synthesis of Acetyl-CoA
Synthesis of glucose from pyruvate
Synthesis of ATP by oxidative phosphorylation
b
Glucagon binds to the glucagon recepton on the cell surface. The resulting downstream signalling ultimately inhibits glycolysis by
preventing the phosphorylation of glucose
blocking the GLUT4 transporter
stimulating the formation of fructose 2,6 bisphosphate
phosphorylation of phosphofructokinase 2
d
Which of the following statements is false?
More ATP is produced following the citric acid cycle than during glycolysis
NADH and QH2 are directly converted to ATP in the mitochondrion
The citric acid cycle produces reduced coenzymes for the electron transport chain
The pyruvate dehydrogenase complex is regulated by phosphorylation
b
Which statement about glucose metabolism is incorrect?
In animals, triglycerides can be converted to glucose after formation of acetyl coA
Blood glucose levels can be maintained by formation of glucose from pyruvate
Glucose can be converted into triglycerides to be stored in adipose tissue
Amino acids can be utilised to maintain the levels of blood glucose
a
Following a meal and fasting, in which order are the different sources of glucose used to maintain blood glucose levels?
Dietary glucose first, then fats, then glycogen
Dietary glucose first, then glycogen, then proteins
Glycogen first, then proteins, then fats
Fats first, then glycogen, then proteins
b
Which metabolite represents the convergence of carbohydrate, fat and protein catabolisms and directly enters the citric acid cycle?
Pyruvate
Citrate
Acetyl CoA
α-Ketoglutarate
c
Which of the following metabolic pathways both take place within the mitochondrial matrix?
Citric acid cycle, β-oxidation of fatty acids
Citric acid cycle, fatty acid synthesis
Gluconeogenesis, glycolysis
Glycolysis, β-oxidation of fatty acids
a
The conversion from fumarate to malate generates no ATP, GTP nor NADH, nor any redox potential. It is energetically neutral. Why is it present in the TCA cycle?
It allows the cycle to turn in the opposite direction.
It removes a toxic double bond from the cycle.
It has not yet been eliminated by selective pressure (evolution).
It is useful when no energy is required during resting.
It reorganises atoms so that the oxidation of malate to oxaloacetate can occur in the next step.
b
In the electron transport chain, the cofactor that transfers electrons between complexes III and IV is
Coenzyme Q
Cytochrome C
FADH2
NADH
b
The chemiosmotic theory of energy conversions suggests that
osmosis of water across a membrane provides the driving force for ATP formation.
a proton concentration gradient causes a flow of electrons to ATP.
a proton concentration gradient causes the protonation of ATP.
a proton concentration gradient and electrical potential across a membrane provides the driving force for ATP formation.
oxygen consumption is coupled to ADP phosphorylation to make ATP.
an electrical potential across the membrane attracts phosphate ions to the surface and drives ATP formation.
4
The so-called dark reactions of photosynthesis occur in which region of the chloroplast?
Thylakoid membrane
Lumen
Stroma
Intermembrane space
c
Photosystem II complexes that oxidise water using light energy are found whereabouts in the chloroplast?
Stroma
Granal lamellae
Inner membrane
Outer membrane
Stromal lamellae
Lumen
b
During illumination, the pH of the stroma is
alkaline
acidic
neutral
a
During ATP generation,
protons accumulated in the lumen pass into the stroma through the H+-ATPase complexes in the stromal lamellae.
protons accumulated in the intermembrane space pass into the stroma through the H+-ATPase complexes in the stromal lamellae.
protons accumulated in the lumen pass into the intermembrane space through the H+-ATPase complexes in the stromal lamellae.
protons accumulated in the stroma pass into the lumen through the H+-ATPase complexes in the stromal lamellae.
a
