Biochemistry & Cell Biology: How Cells Harvest Energy

Comprehensive practice flashcards covering the harvesting of energy, aerobic and anaerobic respiration, glycolysis, the Krebs cycle, electron transport, and catabolism of proteins and fats.

__________ are organisms that obtain energy by absorbing radiant energy of sunlight and using it to form organic compounds through photosynthesis.

Autotrophs

The process where cells utilize enzyme-facilitated redox reactions to take energy from food sources and convert it to ATP is known as __________.

cellular respiration

An atom or a molecule that loses an electron is said to be __________, while one that gains an electron is said to be reduced.

oxidized

In aerobic respiration, the final electron acceptor is __________.

oxygen

The structure of $NAD^+$ is composed of two nucleotides: Nicotinamide monophosphate (NMP) and __________ (AMP).

Adenosine monophosphate

__________ phosphorylation involves forming ATP by transferring a phosphate group directly to ADP from a phosphate-bearing molecule like phosphoenolpyruvate (PEP).

Substrate-level

Oxidative phosphorylation synthesizes ATP using the enzyme __________ and energy from a proton ($H^+$) gradient during chemiosmosis.

ATP synthase

The first stage of aerobic respiration, __________, occurs in the cytoplasm and converts glucose into two 3-carbon pyruvates.

glycolysis

The reactions 1-3 of glycolysis are known as __________ reactions, which convert glucose to fructose 1,6-bisphosphate and require 2 ATP.

priming

Pyruvate oxidation is catalyzed by a multienzyme complex called __________.

pyruvate dehydrogenase

The 2-carbon acetyl unit from pyruvate enters the Krebs cycle by being attached to __________, which is recycled for further oxidations.

coenzyme A (CoA)

In the first reaction of the Krebs cycle, the 4-carbon oxaloacetate combines with an acetyl group to produce the 6-carbon molecule __________.

citrate

At the end of the Krebs cycle, the oxidation of one glucose molecule yields exactly __________ molecules of $FADH_2$.

$$2$$

In the Electron Transport Chain, the mobile electron carrier __________ transfers electrons from the $bc_1$ complex to the cytochrome oxidase complex.

Cytochrome c

According to the transcript, one molecule of NADH provides enough energy to transport __________ protons across the inner mitochondrial membrane.

$$10\,H^+$$

Synthesizing 1 ATP molecule requires __________ protons to pass through the ATP synthase.

$$4\,H^+$$

In eukaryotes, the theoretical yield of 32 ATP is reduced to __________ because it takes 1 ATP to transport each cytoplasmic NADH into the mitochondria.

$$30$$

The enzyme phosphofructokinase is allosterically inhibited by __________ and citrate.

ATP

Increased levels of __________ will activate phosphofructokinase, leading to an increase in pyruvate production.

ADP

The process of __________ respiration uses inorganic molecules other than oxygen, such as sulfate ($SO_4$), as the final electron acceptor.

anaerobic

In __________ fermentation by muscle cells, electrons are transferred from NADH directly to pyruvate.

lactic acid

Before entering glycolysis or the Krebs cycle, amino acids must undergo __________ to remove their amino groups.

deamination

Fatty acids are converted to acetyl-CoA through a series of reactions known as __________.

$$\beta\text{ oxidation}$$