K101 Exam 2

What organelle is the primary site of ATP synthesis in eukaryotic cells?

Mitochondrion

Which cell is most efficient in eliminating waste based on surface area to volume ratio?

A cell with the highest surface area to volume ratio.

Which plant cell organelle does NOT contain its own DNA and ribosomes?

Lysosome

What structures are found in both Elodea (plant) cells and liver cells but not in bacterial cells?

Mitochondria

What limits the maximum size of a cell?

The surface area to volume ratio of cytoplasm

Which structures are common to both plant and animal cells?

Plasma membrane and mitochondrion

What are desmosomes, gap junctions, plasmodesmata, and tight junctions examples of?

Intercellular junctions

Microtubules

Spiral strands of protein molecules that form a tubelike structure

Microfilaments

Long, thin fibers that function in the movement and support of the cell

Intermediate filaments

Threadlike proteins in the cell's cytoskeleton that are roughly twice as thick as microfilaments

What organelle is involved in Tay-Sachs disease due to the lack of Hexaminidase A?

Lysosome

Which disease is NOT associated with alterations in the ECM?

Sickle Cell Disease

What organelle is malfunctioning in Adrenoleukodystrophy (ALD)?

Peroxisome

How is cholesterol brought into cells from the bloodstream?

Receptor-mediated endocytosis

What process do white blood cells use to engulf bacteria?

Phagocytosis

Which molecule is most likely to move through the plasma membrane by passive diffusion?

Carbon dioxide

How do antibodies from breastmilk enter the cells lining a baby's digestive tract?

Endocytosis

Why does water pass quickly through cell membranes?

It moves through aquaporins in the membrane.

What type of reaction is ATP hydrolysis?

An exergonic reaction

Which reaction could be coupled to ATP hydrolysis to create a phosphorylated intermediate?

Glucose --> Glucose-6-Phosphate; G = +5.2 kcal/mole

What is a noncompetitive inhibitor?

A substance that reduces the activity of an enzyme regardless of the concentration of the substrate.

What is an allosteric activator?

A molecule that binds to an enzyme at a site other than the active site, enhancing the enzyme's activity.

What characterizes anabolic pathways?

Anabolic pathways involve the synthesis of larger molecules from smaller ones and are typically endergonic.

What is the ΔG of an exergonic reaction that uses pancreatic lipase to break down fatty acids?

-282 kcal/mole

How does temperature affect enzyme activity in the human stomach?

A fever of 41°C (106°F) would likely denature the enzymes, slowing or stopping their function.

How do enzymes affect the activation energy of reactions?

Enzymes lower the activation energy, increasing the reaction rate.

What is feedback inhibition in enzyme regulation?

A process where the accumulation of a product inhibits an earlier step in the pathway, regulating enzyme activity.

What is the main product of glycolysis?

Glycolysis produces a net of 2 ATP, 2 NADH, and 2 pyruvate.

What occurs during the Krebs cycle?

Acetyl-CoA combines with oxaloacetate to form citric acid, and NAD+ is reduced to form NADH.

What process is likely causing muscle soreness during intense exercise?

Lactic acid fermentation occurs when muscles run out of oxygen.

What is produced during alcoholic fermentation by yeast?

Ethanol and carbon dioxide are produced when yeast ferment grape juice in the absence of oxygen.

What enters the Krebs cycle after pyruvate oxidation?

Acetyl-CoA enters the Krebs cycle.

Which enzymes are involved in the first three steps of glycolysis?

Hexokinase, phosphofructokinase (PFK), and pyruvate kinase.

What is the effect of high ATP concentration on enzyme C in glycolysis?

High ATP concentration binds to enzyme C, inhibiting its activity through feedback inhibition.

What happens to FADH during the Krebs cycle?

FADH accepts two electrons to form FAD+.

What is the significance of pressure-release valves in wine fermentation?

They relieve pressure caused by the production of CO2 during fermentation.

What is the role of enzymes in biochemical reactions?

Enzymes act as catalysts to speed up reactions by lowering activation energy.

What is the difference between catabolic and anabolic reactions?

Catabolic reactions break down molecules to release energy, while anabolic reactions build larger molecules and consume energy.

What is the outcome of glycolysis in terms of energy carriers?

Glycolysis produces 2 NADH, which are energy carriers used in cellular respiration.

What is the primary function of amylase?

Amylase breaks down starch into sugars in the mouth.

What is the optimum temperature for pepsin activity?

Pepsin functions optimally at 37°C in the stomach.

What is the role of trypsin in digestion?

Trypsin breaks down proteins in the small intestine at an optimal temperature of 37°C.

What is the role of malate dehydrogenase?

Malate dehydrogenase catalyzes the conversion of malate to oxaloacetate in the citric acid cycle.

What is the function of α-ketoglutarate dehydrogenase?

α-ketoglutarate dehydrogenase catalyzes the conversion of α-ketoglutarate to succinyl-CoA in the citric acid cycle.

What does isocitrate dehydrogenase do?

Isocitrate dehydrogenase catalyzes the conversion of isocitrate to α-ketoglutarate, producing NADH.

What is the role of succinate dehydrogenase?

Succinate dehydrogenase catalyzes the conversion of succinate to fumarate in the citric acid cycle, also participating in the electron transport chain.

What is the function of hexokinase?

Hexokinase catalyzes the phosphorylation of glucose to glucose-6-phosphate in glycolysis.

What does phosphofructokinase do?

Phosphofructokinase catalyzes the phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate, a key regulatory step in glycolysis.

What is the role of pyruvate kinase?

Pyruvate kinase catalyzes the conversion of phosphoenolpyruvate to pyruvate, producing ATP in glycolysis.

What does phosphoglycerokinase do?

Phosphoglycerokinase catalyzes the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate, generating ATP.

What is the function of PEP carboxylase in photosynthesis?

PEP carboxylase catalyzes the fixation of carbon dioxide to phosphoenolpyruvate, forming oxaloacetate in C4 photosynthesis.

What is the role of Rubisco?

Rubisco catalyzes the reaction of carbon dioxide with ribulose bisphosphate (RuBP) in the Calvin cycle.

What does NADP+ reductase do?

NADP+ reductase catalyzes the reduction of NADP+ to NADPH during the light reactions of photosynthesis.

What is the function of ATP synthase?

ATP synthase synthesizes ATP from ADP and inorganic phosphate using the proton gradient generated during the light reactions.

What molecule is oxidized in photosynthesis?

Water (H2O) is oxidized to produce oxygen (O2) during the light reactions.

What molecule is reduced in photosynthesis?

Carbon dioxide (CO2) is reduced to form glucose (C6H12O6) during the Calvin cycle.

What are the products of the light reactions of photosynthesis?

The light reactions produce ATP, NADPH, and oxygen (O2).

What is the primary function of the Calvin cycle?

The Calvin cycle converts carbon dioxide into glucose using ATP and NADPH produced in the light reactions.

What happens during the regeneration phase of the Calvin cycle?

RuBP is regenerated from G3P, allowing the cycle to continue.

Why do C4 plants photosynthesize more efficiently than C3 plants?

C4 plants use PEP carboxylase to initially fix CO2, minimizing photorespiration.

What is the effect of replacing blood plasma with distilled water?

Red blood cells will swell and likely lyse because the plasma becomes hypotonic compared to the cells.

What occurs in a dialysis experiment with a starch solution?

If amylase is added, glucose will diffuse from the area of higher concentration to lower concentration through the membrane.

What does the Rf value represent in chromatography?

The Rf value is the ratio of the distance traveled by the pigment to the distance traveled by the solvent front.

What is the purpose of a negative control in an enzyme assay?

A negative control serves to demonstrate that no color change occurs without the enzyme's activity.

What is the significance of color change in a peroxidase assay?

Color change indicates the reduction of guaiacol by peroxidase, producing a reddish-brown product.

What happens to a green pigment in thin-layer chromatography?

A non-polar solvent allows the green pigment to travel with the solvent front, indicating its polarity.

What is the difference between absorption and action spectra for chlorophyll?

Absorption spectra show light absorption by chlorophyll, while action spectra show the effectiveness of different wavelengths in driving photosynthesis.