C1.2 Cell respiration Notes

ATP

Adenosine triphosphate; the primary energy currency of the cell.

Energy Distribution

ATP acts like a quick charge for cells, providing energy precisely when needed.

High-Energy Phosphate Bonds

The unstable bonds between phosphate groups in ATP that release energy upon hydrolysis.

ADP

Adenosine diphosphate; the end product of ATP hydrolysis.

Recycling of ATP

ATP is converted into ADP and inorganic phosphate, which can be re-phosphorylated to regenerate ATP.

Active Transport

The movement of molecules against their concentration gradient requiring energy.

Anabolic Reactions

Metabolic processes where smaller molecules are built into larger ones, consuming ATP.

Intracellular Movement

Movement of organelles within the cell powered by ATP.

Muscle Contraction

A process that requires ATP as myosin heads detach and reattach to actin filaments.

Hydrolysis of ATP

The process of breaking down ATP to ADP, releasing energy.

Substrate-Level Phosphorylation

Direct transfer of phosphate from a substrate to ADP to form ATP.

Glycolysis

The metabolic pathway that converts glucose into pyruvate, yielding ATP and NADH.

Lactate

The product of pyruvate reduction in anaerobic respiration, allowing NAD⁺ to be regenerated.

Alcoholic Fermentation

A process in yeast where pyruvate is converted to ethanol and CO₂.

Link Reaction

The conversion of pyruvate to acetyl-CoA, connecting glycolysis to the Krebs cycle.

Krebs Cycle

A series of reactions in the mitochondrial matrix that further oxidize acetyl-CoA.

Electron Transport Chain (ETC)

A series of protein complexes that transfer electrons, producing ATP and water.

Chemiosmosis

The process of protons flowing back into the mitochondrial matrix to produce ATP.

Terminal Electron Acceptor

Oxygen acts as the final electron acceptor in the ETC, forming water.

NADH

Nicotinamide adenine dinucleotide; a carrier of high-energy electrons.

Oxidation-Reduction Reactions

Reactions where oxidation (loss of electrons) and reduction (gain of electrons) occur simultaneously.

Proton Gradient

A difference in proton concentration across a membrane, used to drive ATP synthesis.

ATP Synthase

An enzyme that synthesizes ATP by utilizing the proton gradient created by the ETC.

Respiratory Substrates

Carbohydrates, lipids, and proteins that are used in cellular respiration.

Aerobic vs. Anaerobic Respiration

Aerobic uses oxygen and produces more ATP; anaerobic occurs without oxygen and produces less ATP.

Phosphorylation

The addition of a phosphate group to a molecule, increasing its energy.

Decarboxylation

The removal of a carbon atom from a molecule, releasing it as CO₂.

FADH₂

Flavin adenine dinucleotide; another electron carrier that donates electrons to the ETC.

Energy Yielding

The amount of ATP produced from a substrate during cellular respiration.

ATP Hydrolysis Reaction

ATP + H₂O → ADP + Pi + Energy.

Universal Energy Currency

ATP is used by nearly all cellular life to power processes.

Examples of Anabolic Processes

DNA replication, protein synthesis, and polysaccharide formation.

ATP Recycling

Continuous conversion between ATP and ADP to maintain energy supply.

Enzyme Activity

Enzymes speed up cellular respiration, affected by factors like temperature.

Oxygen Availability

The presence of oxygen affects the type of respiration (aerobic vs anaerobic).

pH Levels

Enzyme activity in respiration can be affected by changes in pH.

Substrate Concentration

Higher concentrations of glucose can increase the respiration rate.

Respirator Experiments

Using respirometers to measure the rate of respiration based on oxygen consumption.

ATP Production in Krebs Cycle

Produces 3 NADH, 1 FADH₂, 1 ATP, and releases 2 CO₂.

Efficient Energy Conversion

The ETC allows efficient transfer of energy from electrons to ATP.

Role of Oxygen in Respiration

Oxygen accepts electrons in the ETC, maintaining the flow and ATP production.

Glycolysis Location

Occurs in the cytoplasm and does not require oxygen.

Enzyme Specificity

Glycolysis involves specific enzymes for each conversion step.

Phosphorylated Glucose,

Traps glucose in the cell and primes it for breakdown.

Proton Motive Force

The potential energy stored in the proton gradient drives ATP synthesis.

Effect of Temperature on Respiration Rate

Higher temperatures increase enzyme activity but can lead to denaturation.

Anaerobic Conditions

Under conditions where oxygen is limited, cells switch to anaerobic respiration.

Carbohydrates vs. Lipids as Energy Sources

Carbohydrates are quick energy sources; lipids yield more energy per gram.

Cellular Economy of ATP

ATP functions as the currency which provides energy for cellular purchases.

Muscle Fatigue and Lactate Accumulation

Lactate buildup from anaerobic respiration can lead to fatigue.

Link Reaction Overview

Converts pyruvate to acetyl-CoA, producing NADH and CO₂.

Acetyl-CoA Importance

Acts as the substrate for the Krebs cycle, fully oxidizing carbon.

Energy Production in Glycolysis

Generates small amounts of ATP and NADH from glucose breakdown.

ATP Usage in Cell Processes

ATP powers active transport and anabolism in cells.

Substrate-Level Phosphorylation Steps

Direct transfer of phosphate to ADP from a biochemical pathway.

Lactic Acid Fermentation Example

C6H12O6 → 2 C3H6O3; regenerates NAD⁺ for glycolysis.

Alcoholic Fermentation Overview

Yeast converts pyruvate to ethanol and CO₂ in anaerobic conditions.

Krebs Cycle Function

Processes acetyl groups to extract energy from carbohydrates and lipids.

Flow of Electrons in ETC

Transfers through carrier proteins, extracting energy stepwise.

ATP Synthase Mechanism

Utilizes proton flow to drive the mechanical rotation needed for ATP formation.

Final Products of Fermentation in Yeast

Ethanol and CO₂ as metabolic waste during anaerobic respiration.

Oxidative Phosphorylation Purpose

To generate ATP using electron transport coupled with chemiosmosis.

Hydrolysis for Energy Release

Breaking nucleotide bonds in ATP releases energy for cellular work.

NAD+ Recycling During Respiration

Essential for continued function of glycolysis and the Krebs cycle.

Oxygen's Role in Electrons Flow

Maintains electron transport and prevents accumulation.

Cell Respiration Overview

The metabolic processes that convert biochemical energy from nutrients into ATP.

Difference Between NAD⁺ and NADH

NAD⁺ is the oxidized form, while NADH is the reduced form carrying electrons.

Beta-Oxidation Overview

Fatty acids are converted to acetyl-CoA before entering the Krebs cycle.

Cellular Respiration Yield per Glucose

Exact ATP count varies but averages around 30-38 ATP per glucose molecule.

Lactate Formation in Muscles

Occurs when oxygen is lacking during high-intensity exercise.

Definition of Fermentation

The metabolic process that generates energy without oxygen, resulting in different end products.

Intramitochondrial Organization

The structure within mitochondria facilitates efficient ATP production.

Ethanol Production in Yeast Fermentation

Yeast converts sugars into ethanol and CO₂ during fermentation.

Regeneration of NAD+ During Anaerobic Processes

Ensures that glycolysis can continue producing ATP in absence of oxygen.

ATP Synthase Location

ATP synthase is embedded in the inner mitochondrial membrane.

Mitochondrial Proton Gradient Function

Drives ATP production through chemiosmosis via ATP synthase.

Cell Membrane and Active Transport

Requires ATP to move molecules against their concentration gradient.

Comparing Fats and Sugars as Energy Sources

Fats yield more energy but require oxygen for full oxidation.

Cellular Respiration Variability

Cells can adapt metabolism based on available substrates and oxygen.

Human vs. Yeast Anaerobic Processes

Humans produce lactate while yeast produces ethanol and CO₂.

Anaerobic Respiration Pathway Products

Generates lactate or ethanol and reuses NAD⁺ to maintain glycolysis.

Role of Oxygen as an Accepting Agent

Enables the ETC to function by accepting electrons at the end.

Hydrogen Carriers in Cell Respiration

Molecules like NAD+ that transport high-energy electrons between metabolic pathways.

Respiration in Eukaryotic Cells

More evolved with mitochondria for efficient ATP synthesis.

Acetyl-CoA Contribution to Respiration

It provides 2-carbon units for the Krebs cycle.

Krebs Cycle Outputs Summary

Convert acetyl-CoA and produce NADH, FADH₂, ATP, and CO₂.

Response in Exercise to Oxygen Deficit

Switch to anaerobic pathways to maintain ATP production.