Metabolism and Cellular Respiration

• Metabolism and cellular respiration are important cellular functions

Metabolism

• Includes anabolic and catabolic reactions
• Anabolic reactions lead to growth
• Catabolic reactions create energy
• Free radicals oxidize organic molecules

Cellular Respiration

• Organic compounds, like glucose, break apart into ATP molecules
• ATP leads to homeostasis and other cellular functions:
• Cell growth and division
• Breakdown and replacement of cell components
• Secretion, contraction, and propagation of action potentials
• Building energy reserves and storing fuel as fat

ATP Production

• Requires food and oxygen
• Oxygen acts as an electron acceptor and is reduced
• Carbon dioxide is released
• Heat is released to maintain body temperature

Glucose

• Liver cells take up glucose
• Glucose is released within cells
• Glucose binds to a receptor in the plasma membrane of hepatocytes, facilitating glucose channels

Biochemical Reactions

• Exercising speeds up biochemical reactions

Cellular Respiration

• Divided into anaerobic and aerobic reactions

Anaerobic and Aerobic Respiration

• Anaerobic does not require oxygen
• Aerobic requires presence of oxygen

Aerobic Respiration

• Involves 4 phases:
• Glycolysis, transition reaction, citric acid cycle, and the electron transport chain

Glycolysis

• Does not require oxygen
• The start molecule
• There is a product formed at the end
• There is a number of ATPs produced
• There are NADH's in the process

Metabolism - Chemical Reactions

• Electrons are released by glucose as it is converted to pyruvic acid (sugar)
• Electron carriers, like nicotinamide adenine dinucleotide (NAD), act as coenzymes
• NAD+ + H+ → NADH

Anaerobic-Fermentation

• Happens without oxygen
• Glycolysis stops because NAD+ is required
• Fermentation then provides NAD+ to glycolysis

Fatigue

• Heart weakness leads to less oxygen delivered to muscles
• Muscle cells don't get enough oxygen
• Lactic acid formation occurs
• All leading to fatigue and cramping

Aerobic Respiration

• Oxygen goes to the mitochondria
• Pyruvate sugar + 2NAD → 2Acetyl sugar-CoA + 2CO2 + 2 NADH
• CoA is known as pantothenic acid vitamin B
• After glycolysis, steps transition reaction, citric acid cycle series of reactions, and electron transport chain

Transition Reaction

• 3 steps occur in the mitochondria matrix

Transition Reaction Steps

• Pyruvates are oxidized
• Electron energy is stored in NADH2
• Two carbons are released as CO2 due to decarboxylation

Citric Acid Cycle

• A series of reactions involving eight different enzymes within the mitochondrial matrix
• Involves 2 electron carriers:
• Nicotinamide adenine dinucleotide (NAD) (niacin-vitB) → NAD+ +H+ →NADH
• Flavin adenine dinucleotide (FAD) (riboflavin-vitB) → FAD2+ + 2H+ →FADH2

Electron Transport Chain

• Occurs in the inner membrane of mitochondria
• A row of proteins and coenzymes in the inner mitochondria membrane
• Energy is extracted from NADH & FADH2
• Produces 32, 34, or 38 molecules of ATP.

Electron Transport Chain

• Electrons are donated
• It creates a gradient
• ATP is synthesised at an enzyme in the membrane

Recycling Coenzymes

• Increases efficiency
• NADH delivers hydrogen's and returns as NAD+ to pick up more
• Hydrogen's and oxygen combine to form water
• Without O2, NADH cannot release H+
• NADH can no longer recycled to NAD+

Lactic Acid Fermentation

• Happens in muscle cells
• Anaerobic weight lifting is an anaerobic exercise

No Oxygen

• Anaerobic metabolism:
• Glycolysis
• Fermentation
• Pyruvate converted to
• Lactic acid (animals)
• Ethanol (yeast)
• Only yields 2 ATP

No Glucose Alternative

• Breakdown of proteins and fats joins the carbohydrate pathway

• Carbohydrates yields 36 ATP
• Fat yields 175 ATP
• Protein yields 16 ATP

Deamination

• Occurs in the liver
• Ammonia turns into urea
• Urea is released in the bloodstream and measured in blood
• BUN (blood urea nitrogen) normal levels are between 5-25mg/dL