Biochemistry: Redox Reactions and Metabolism

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Questions and Answers

What occurs during gluconeogenesis in the liver?

Production of urea from ammonia

Storage of triglycerides in adipose tissue

Conversion of lactic acid into glucose (correct)

Breakdown of glycogen into glucose

In which location does the citric acid cycle take place?

Nucleus of the cell

Liver cell membrane

Mitochondrial matrix (correct)

Cytoplasm of the cell

Which process is responsible for creating a proton gradient during ATP synthesis?

Glycolysis

Lactic Acid Fermentation

Krebs Cycle

Electron Transport Chain (correct)

What happens to electrons at the end of the electron transport chain?

They combine with oxygen to form water (C) Signup and view all the answers

What is the energy yield of ATP during oxidative phosphorylation?

28 ATP per glucose molecule (B) Signup and view all the answers

During which state is glycogen primarily broken down to release glucose?

Postabsorptive state (D) Signup and view all the answers

What role does heat play in cellular respiration?

It helps maintain body temperature (A) Signup and view all the answers

What happens to ADP during cellular respiration?

It is recycled back into ATP (C) Signup and view all the answers

What happens during oxidation in a redox reaction?

Loss of electrons (D) Signup and view all the answers

Which molecule is reduced during cellular respiration?

NAD⁺ (B) Signup and view all the answers

What best describes the process of catabolism?

Breaking down larger molecules into smaller ones (A) Signup and view all the answers

What is the overall equation for cellular respiration?

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ~32 ATP (B) Signup and view all the answers

During glycolysis, how many ATP are required to start the process?

2 ATP (C) Signup and view all the answers

What is the fate of pyruvate under low oxygen conditions?

Converted to lactic acid (B) Signup and view all the answers

Which of the following statements about triglycerides is correct?

They store excess calories for long-term energy. (C) Signup and view all the answers

What condition leads to the formation of lactic acid?

Low oxygen availability (D) Signup and view all the answers

Study Notes

Redox Reactions

Redox reactions involve electron transfer.
Oxidation is the loss of electrons (or hydrogen).
Reduction is the gain of electrons (or hydrogen).
Reduced molecules have more potential energy.

Cellular Respiration

Glucose is oxidized to CO₂ during cellular respiration.
NAD+ is reduced to NADH, acting as an electron carrier.

Anabolism vs. Catabolism

Anabolism builds larger molecules from smaller ones, requiring energy.
Catabolism breaks down larger molecules into smaller ones, releasing energy.

Carbohydrate Metabolism

Cellular respiration equation: CH₂O + 6O₂ → 6CO₂ + 6H₂O + ~32 ATP
Glycolysis occurs in the cytoplasm.
It requires 2 ATP initially and produces a net of 2 ATP.
Pyruvate fate depends on oxygen levels.
- Oxygen present: Converted to acetyl-CoA and enters the citric acid cycle.
- Low oxygen: Converted to lactic acid.
Lactic acid is processed in the liver to regenerate glucose. (Gluconeogenesis)
Citric acid cycle occurs in the mitochondrial matrix.
Carbon and oxygen are released as CO₂.
Hydrogen is transferred to NAD+ and FAD, reducing them to NADH and FADH₂.
Electron Transport Chain (ETC) utilizes NADH/FADH₂ electrons to create a proton gradient.
ATP Synthase generates ATP from this gradient.
~28 ATP is produced per glucose molecule from ETC.
Low oxygen halts ETC, reducing ATP production and increasing lactic acid.
Cellular respiration releases heat, helping to maintain body temperature.
ATP is used for cellular functions, recycled into ATP for further respiration.
Glycogen is a glucose storage polysaccharide in the liver and skeletal muscles.

Lipid Metabolism

Excess calories are converted into triglycerides for storage.
Triglycerides are broken down into glycerol (enters glycolysis) and fatty acids (β-oxidation to acetyl-CoA, entering the citric acid cycle).

Amino Acid Metabolism

Transamination transfers an amino group to another molecule, converting amino acids into intermediates for respiration.
This process happens in the liver.
Nitrogen is removed, preparing amino acids for energy production (excreted as urea).

Absorptive vs. Postabsorptive State

Absorptive state (within 4 hours of eating): Glucose is stored as glycogen; triglycerides stored in adipose; amino acids for protein synthesis.
Postabsorptive state (digestive tract empty): Glycogen is broken down for glucose, triglycerides for fatty acids/glycerol, and proteins for keto acids.
Ketones are produced from fats during prolonged fasting for energy.
Keto acids originate from amino acid metabolism and enter the citric acid cycle.

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Description

This quiz covers fundamental concepts in biochemistry, focusing on redox reactions, cellular respiration, and the distinctions between anabolism and catabolism. Explore the processes of glucose oxidation and the metabolic pathways involved in energy production. Test your understanding of carbohydrate metabolism and its implications for cellular function.