Chapter 6: How Cells Harvest Chemical Energy - Practice Flashcards

Comprehensive practice flashcards covering cellular respiration stages, redox reactions, fermentation, and metabolic pathways based on BIO 110 lecture notes.

What is the primary function of cellular respiration in cells?

It oxidizes fuel molecules and generates ATP for cellular work.

What are the four main stages of cellular respiration?

Glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation.

What process allows glycolysis and ATP production to continue in the absence of oxygen?

Fermentation.

In an ecosystem, where does the energy for life ultimately come from?

The Sun.

During photosynthesis, atoms of which two substances are rearranged using solar energy?

$CO_{2}$ and $H_{2}O$.

What gas is consumed during cellular respiration and released during photosynthesis?

Oxygen ($O_{2}$).

In which organelle does cellular respiration take place in eukaryotic cells?

Mitochondria.

How is respiration defined in the context of gas exchange (breathing)?

The exchange of gases where organisms obtain $O_{2}$ from the environment and release $CO_{2}$ as a waste product.

Is cellular respiration an endergonic or exergonic process?

Exergonic (energy-releasing).

Approximately what percentage of the energy stored in glucose is captured as ATP during cellular respiration?

$34\%$.

What happens to the energy from glucose that is not captured as ATP?

It is lost as heat.

According to Fig. 6.4, how many kcal per hour are consumed by a 67.5-kg person running at 8-9 mph?

$979$.

In a redox reaction, what is the term for the loss of electrons from a substance?

Oxidation.

In a redox reaction, what is the term for the addition of electrons to a substance?

Reduction.

What is the general chemical equation for the oxidation of glucose in cellular respiration?

$C_{6}H_{12}O_{6} + 6O_{2} \rightarrow 6CO_{2} + 6H_{2}O + \text{ATP} + \text{Heat}$.

Which coenzyme assists in oxidizing glucose by accepting electrons?

$NAD^{+}$.

What enzyme removes two hydrogen atoms from glucose and transfers them to $NAD^{+}$?

Dehydrogenase.

When $NAD^{+}$ is reduced, what molecule does it become?

$NADH$.

Where is the electron transport chain located in the cell?

The inner mitochondrial membrane.

What is the final electron acceptor at the end of the electron transport chain?

Oxygen.

Where in the cell does glycolysis occur?

The cytosol.

How many carbons does one molecule of glucose have compared to one molecule of pyruvate?

Glucose has 6 carbons; each pyruvate has 3 carbons.

What is the net gain of ATP molecules per glucose molecule in glycolysis?

$2$.

What occurs during steps 1-4, the Energy Investment Phase of glycolysis?

Two ATP molecules are used to add phosphate groups to glucose, energizing it and eventually splitting it into two G3P molecules.

What occurs during the Energy Payoff Phase (steps 5-9) of glycolysis?

G3P molecules are oxidized, $NAD^{+}$ is reduced to $NADH$, and ATP is formed.

What are the net products of glycolysis from one molecule of glucose?

Two ATP molecules and two $NADH$ molecules.

Where does pyruvate oxidation occur?

The mitochondria.

In pyruvate oxidation, what three-carbon molecule is converted into a two-carbon molecule?

Pyruvate.

What carbon-containing waste product is released during pyruvate oxidation and the citric acid cycle?

$CO_{2}$.

What molecule is formed when the two-carbon group from pyruvate joins with coenzyme A?

Acetyl coenzyme A (acetyl CoA).

What four-carbon molecule does the acetyl group combine with at the beginning of the citric acid cycle?

Oxaloacetate.

What is the first six-carbon molecule produced in the citric acid cycle?

Citrate.

For each turn of the citric acid cycle, how many $NADH$ and $FADH_{2}$ molecules are produced?

Three $NADH$ and one $FADH_{2}$.

How many molecules of ATP are formed per turn of the citric acid cycle?

$1$.

Which two molecules shuttle electrons to the electron transport chain in Stage 3?

$NADH$ and $FADH_{2}$.

What percentage of the ATP produced by cellular respiration is generated by oxidative phosphorylation?

Approximately $90\%$.

What is the process called where ATP synthase uses the $H^{+}$ gradient to phosphorylate ADP?

Chemiosmosis.

What component acts as a "rotor" and uses the flow of $H^{+}$ to drive ATP synthesis?

ATP synthase.

How does brown fat differ from white fat regarding mitochondrial activity?

Brown fat contains mitochondria that burn fuel to produce heat instead of making ATP.

Under what conditions is brown fat typically found in adults?

In adults who are thinner or during cold weather.

According to the summary (Page 35), what is the total maximum yield of ATP per glucose molecule?

About $32\,ATP$.

How many $NADH$ molecules are produced in total from the citric acid cycle per glucose molecule?

$6\,NADH$.

What happens to pyruvate during lactic acid fermentation?

It is reduced to lactate.

In which human cells does lactic acid fermentation occur when oxygen is scarce?

Muscle cells.

Where is lactate converted back into pyruvate after exercising?

The liver.

What are the products of alcohol fermentation?

Ethanol and $CO_{2}$.

What type of organism is yeast, which can survive in both aerobic and anaerobic conditions?

Facultative anaerobes.

Why is ethanol released by yeast during fermentation considered a waste product?

It is toxic to the yeast.

What does a cell do to $NADH$ during fermentation to keep glycolysis running?

It recycles $NADH$ back to $NAD^{+}$.

Why was glycolysis likely the first metabolic pathway to evolve in ancient prokaryotes?

It occurs in the cytoplasm, does not require membrane-bound organelles, and works without oxygen, which was scarce in Earth's original atmosphere.

What is the stored form of glucose in the human liver called?

Glycogen.

What are the three main types of food molecules used as fuel for cellular respiration?

Carbohydrates, fats, and proteins.

Into what two components are fats broken down before entering metabolic pathways?

Glycerol and fatty acids.

Which part of a fat molecule enters the glycolysis pathway as G3P?

Glycerol.

What must be removed from amino acids before they can be used for fuel in cellular respiration?

Amino groups.

What is the term for the process of using food molecules to build structures and perform functions?

Biosynthesis.

Which activities from Figure 6.4 consume the same amount of kcal per hour (490)?

Walking (4 mph) and Dancing (fast).

What is the net ATP production specifically from the citric acid cycle per glucose molecule?

$2\,ATP$.

What enzyme is responsible for synthesizing ATP during the final stage of respiration?

ATP synthase.

What are all the chemical processes in your body collectively called?

Metabolism.