Chapter 8
Which reaction releases free energy?
Exergonic reactions (apparently)
Oh Jesus it's cellular respiration okay here we go.
What is the summary equation of cellular respiration?
Glucose + Oxygen produces Carbon dioxide, water, and energy
Purpose is to convert chemical energy stored in glucose into stable cellular energy (ATP)
Where exactly does the Krebs cycle take place in eukaryotic cells?
The mitochondrial matrix.
What are the three laws of thermodynamics?
1. Conservation of energy
2. Entropy increases in a closed system
3. Entropy approaches a constant value at absolute zero
(I feel like I used to know these but definitely don't now)
Endergonic Reactions
What is the difference between fermentation and cellular respiration?
Cellular respiration is an oxygen-dependent (aerobic) process that efficiently generates a lot of ATP.
Fermentation is an anaerobic process occurring in the cytoplasm, yielding only 2 ATP, used when oxygen is scarce. Respiration produces CO2 and water, fermentation produces lactic acid or ethanol.
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How many times does the Krebs cycle turn per molecule of glucose?
Two times, because glycolysis produces two pyruvates, which are converted into two Acetyl-CoA molecules.
How is feedback inhibition used to maintain appropriate levels of enzymes and enzyme products in a pathway?
Feedback inhibition maintains appropriate metabolite levels by using the end product of a metabolic pathway to bind to and inhibit an early enzyme in that same pathway. As the end product accumulates, it acts as an inhibitor to "turn off" the pathway, conserving energy and preventing overproduction, resuming once levels decrease
What is metabolism?
The totality of an organism’s chemical reactions. Manages the materials and energy resources of a cell
What is Glycolysis?
Glycolysis is a fundamental metabolic pathway occurring in the cell's cytosol that breaks down one 6-carbon glucose molecule into two 3-carbon pyruvate molecules, generating a net gain of 2 ATP and 2 NADH molecules
What is the purpose of the proton gradient in the electron transport chain?
The gradient stores potential energy. Protons flow back across the membrane through ATP synthase, which catalyzes the phosphorylation of ADP to ATP.
What is the correct order of metabolic reactions in the oxidation of glucose?
Glycolysis
Pyruvate Oxidation
Citric Acid Cycle
Electron Transport Chain
What are catabolic and anabolic pathways?
Catabolic pathways release energy by breaking down complex molecules into simpler compounds
Eg. digestive enzymes break down food 🡪 release energy
Anabolic pathways consume energy to build complex molecules from simpler ones
Eg. amino acids link to form muscle protein
What is the process that brings pyruvate from the cytosol into the mitochondria and introduces it into the citric acid cycle?
Pyruvate oxidation
Which of the following best describes the role of water in the light-dependent reactions of photosynthesis?
A) It is the final electron acceptor.
B) It provides the electrons to replace those lost by Photosystem II.
C) It absorbs light energy.
D) It fixes carbon dioxide.
B
What is the primary role of oxygen in cellular respiration?
Oxygen acts as the final electron acceptor at the end of the electron transport chain, combining with electrons and hydrogen to form water.
What are some factors that change the shape of the active site of enzymes and how they influence enzyme activity?
Extreme temperatures, pH changes, and inhibitors. These factors break the bonds (hydrogen, ionic) maintaining the enzyme's three-dimensional structure, preventing substrate binding and decreasing or stopping catalytic activity
What is the function of the enzyme phosphofructokinase?
Phosphofructokinase (PFK) is a critical rate-limiting enzyme in glycolysis that catalyzes the phosphorylation of fructose 6-phosphate into fructose 1,6-bisphosphate using ATP. It acts as a primary control point for glucose metabolism, determining the rate of energy production, and is heavily regulated by cellular energy levels
What is Pyruvate Oxidation?
The critical metabolic step connecting glycolysis to the citric acid cycle. It takes place in the mitochondrial matrix of eukaryotes, transforming 3-carbon pyruvate into 2-carbon acetyl-CoA, releasing CO2 and generating NADH, preparing the fuel for the Krebs cycle.
Where do the different stages of aerobic respiration occur in a eukaryote?
Glycolysis occurs in the cytosol, while the Citric Acid Cycle and electron transport chain occur in the mitochondria