Adenosine Triphosphate (ATP)

• Living organisms need energy for movement, nutrition, and excretion
• Cell respiration releases this energy
• Energy releases is transferred to adenosine triphosphate (ATP)

Adenosine Triphosphate (ATP)

• Energy is transferred in small steps; heat loss regulates body temperature in endotherms
• ATP stores chemical energy short-term for cells to use
• Its solubility and size aids its movement throughout cells through facilitated diffusion
• ATP is a universal energy currency used in all organisms
• The hydrolysis of ATP is beneficial as ATP is carried out via ATPase
• A useful amount of energy is released and controls cell processes
• ATP is stable at a cellular pH levels
• ATP is a phosphorylated nucleotide with ribose sugar, adenine base, and three phosphate groups
• ATP breaks down via a reversible reaction; Can be reformed from ADP and Pi, and reused differently

ATP Reliant Life Processes

• Anabolic reactions synthesize macromolecules from smaller units
• Active transport moves molecules against concentration gradients across membranes.
• ATP facilitates the entire cell and its components, like chromosomes

ATP Production and Usage

• On average humans use more than 50 kg of ATP in a day
• The body maintains only about 200g because it is not built-up in large stores of ATP
• ATP is made as cells need it, ADP combines with inorganic phosphate (Pi), which requires energy
• Water is released during ATP synthesis, classifying it as a condensation reaction

Cell Respiration

• A controlled release of energy from organic compounds to produce ATP
• In every cell respiration is a process to release energy
• Energy stored in food (e.g., glucose) is converted into usable forms via a catabolic process
• Glucose from lipids and proteins is the main respiratory fuel

Glycolysis

• Glycolysis is easier for glucose to enter directly
• Proteins are structural and only used when glucose and lipids are not available
• Enzymes control energy release in a series of reactions, forming ATP
• ATP uses a phosphate group, which comes form the breakdown of organic material
• Fuelling anabolic processes, muscle contraction, fuelling active transport, moving molecules and generating heat uses released energy

Anaerobic vs Aerobic Cell Respiration

• Transfers potential energy from nutrients into usable energy for work
• Vital for all living cells; Respiration differs based on oxygen availability
• Aerobic respiration breaks down substrates to produce ATP using oxygen; The substrate is oxidized with energy released
• Anaerobic respiration breaks down a respiratory substrate in absence of oxygen, resulting in less ATP

Aerobic Respiration

• Needs oxygen and yields a large amount of ATP from glucose
• Complete breakdown into CO2 and water yields high energy (~36 ATP molecules)
• CO2 needs excretion and H2O is a byproduct for the organism
• Most reactions occur in the mitochondria

Anaerobic Respiration

• Yields lower energy than aerobic conditions
• Occurs in the cytoplasm without mitochondria intervention; Occurs three ways
• Oxygen supply cannot keep up with the demand in respiring cells for muscle contraction
• Glucose is partially oxidised with only a portion of chemical energy transferred to ATP
• Yields 2 ATP for each glucose, better than zero when oxygen runs out
• Organisms produce ethanol and CO2 or lactate
• Ethanol and CO2 are produced by plants and yeasts
• Lactate is produced by animals

Cell Respiration Rate Factors

• The respiration rate may vary
• The more metabolically active the cell is, an example being muscle cells
• Smaller surface area of organisms, gives a higher respiration rate to compensate heat loss
• When low, cells respire anaerobically
• Glucose supply is of particular importance
• Respiratory rate increases to its temp optimum, where enzymes catalyse reactions
• Carbon dioxide released will decrease pH of cells and tissues

Respirometers

• Used to measure oxygen consumption of organisms
• Experiments use live organisms (seeds or invertebrates)
• A good experiment can be done using seeds than animals
• Respirometers include a container with organisms and air, alkaline solution and connected capillary tube with a graduated scale
• Organisms absorb oxygen and releases CO2 absorbed via alkaline solution
• Pressure is reduced, causing manometer fluid (red) to move toward the organisms
• Can be water baths to maintain controlled air pressure
• Anomalies must be eliminated through repeat readings

Oxidation and Reduction

• Oxidation reactions feature in cellular respiration and photosynthesis
• Redox reactions involve electron transfers with molecules
• Oxidation is a loss of electrons
• Reduction is a gain of electrons
• Oxidation releases energy to surroundings (exergonic)
• Reduction absorbs energy from surroundings (endergonic)
• Molecules donate lose electrons
• Molecules that easily gain electrons are oxidizing agents; Respiration involves molecules that gain electrons

NAD and FAD

• NAD+ gains electrons (becoming NADH)
• FAD gains electrons (becoming FADH2)
• These electron carriers transport electrons to other reactions
• When electrons are lost they return to their original form

Glycolysis High Level

• Glycolysis first stage of respiration; trapping and splitting glucose in the cytoplasm.
• Produces two pyruvate and two NADH.
• Glucose (6C) phosphorylates to fructose-1,6-bisphosphate (6C); This makes the molecule reactive
• Fructose-1,6-bisphosphate (6C) splits into two molecules of triose phosphate (3C)
• Hydrogen is removed and transferred to NAD to form 2 NADH
• Triose oxidises to glycerate-3-phosphate
• Phosphates transfer from ATP to form two ATP

Lactate Production

• In low oxygen conditions that limits respiratory substrates
• Way for cells to produces some ATP via anaerobic respiration
• Glycolysis continues, producing small amounts of ATP
• Occurs differently in different cells, for example pyruvate converts to ethanol and lactate
• Reduced NAD transfers hydrogens to pyruvate to lactate to reoxidise
• Pyruvate is reduced to lactate via enzyme lactate dehydrogenase
• Lactate becomes further metabolised

Metabolisation of Lactate

• Lactate is oxidised to pyruvate which is channelled into Krebs cycle or converts to glycogen for liver storage
• Oxidizing lactate back to pyruvate needs oxygen; Extra oxygen explains why animals breath faster after exercise

Yeast Anaerobic Cell Respiration

• Alchoholic fermentation useful to humans
• Carbon dioxide causes bread dough to rise, while yeast contains a single-celled fungi that can respire aerobically and anaerobically
• Starch mixes with water and yeast; The dough is needs to be kneaded to remain warm
• Yeast grows rapidly whilst its cells hydrolyse starch, then turns to anaerobic
• Carbon dioxide bubbles allow dough to rise and ethanol gets evaporates

The Link Reaction High Level

• Is initiated by pyruvate from glycolysis
• Links glycolysis to the Krebs cycle; Link reaction in the mitochondrial matrix carries out; pyruvate (3C)
• CO2 is removed from pyruvate to create a smaller molecule
• 2C molecule loses hydrogen creating an acetyl compound
• Acetyl compound combines with coenzyme A, thus continuing aerobic respiration and suppling A to the Krebs cycle

Krebs Cycle

• In the mitochondrial matrix, takes a series of enzyme-controlled reactions
• Two carbon (2C) Acetyl CoA enters from the link reaction
• Four carbon compound (4C) called oxaloacetate accepts the 2C acetyl fragment from acetyl CoA to form a six carbon compound (6C) called citrate
• Coenzyme A is released and reused

Krebs Cycle Cont

• Citrate (6C) is then converted back to oxaloacetate (4C) through a series of oxidation-reduction reactions via redox
• Oxaloacetate (4C) regenerates through the redox reactions
• There is two CO2 waste released, then oxidation (dehydrogenation) which created Hatoms
• As the link reaction produces two molecules of acetyl CoA so the Krebs cycle will occur twice

Per Glucose Molecule

• Four CO2, two ATP, six NADH + H+ and Two FADH2 are produced
• Four Carbon C molecule can become cyclical or circular by adding another acetyl CoA

Oxidative Phosphorylation

• Is reliant on protons and electrons in the electron transport chain
• Electrons are given to the electron transport chain from NAD and FAD; Protons released when they lost electrons
• Carrier proteins cause creation of a proton gradient within the mitochondrial matrix
• Protons require ATP synthesis, as they return via gradient
• A series of redox are carried out via a membrane protein

Electron Transport Chain

• Chain is used to transport electrons and move protons (hydrogen ions) across the membrane
• Carriers brings electrons closer; Cristae impermeable; Protons power phosphorylation
• Energy passes through controlled manner to a pair of electrons
• One molecule of reduced NAD produces 3 ATP
• 32 ATP molecules produced when oxidising glucose
• Oxygen final chain electrons
• Oxygen combines with protons

Chemiosmosis

• Chain causes an electrochemical gradient as it releases protons
• Protons accumulate in intermembrane space; the move will power ATP
• Pass through the phospholid bilayer by facilitated diffusion of ATP Synthase
• Is powered by these porotns that turns water wheel
• Catalyses phosphorylation and generates ATP

Lipids and Carbohydrates

• Lipids are an excellent source of energy that transfer twice as much energy per gram
• Carbohydrates contain less oxygen
• Lipids stores a good amount of potential energy as its insoluble
• Lipid oxidation gives more metabolic water than the amount of carbohydrates
• Glycolysis only comes from carbs

2C Actyle Groups

• Fatty acids broken to be 2C acetyl groups and form Acetyl coenyme A, which can enter kerbs cycle