FermentationBioMed/Forensics

KEY CONCEPT Fermentation allows the production of a small amount of ATP without oxygen.

What is Fermentation?

• Cellular respiration refers to a process by which cells convert food into energy.

• Fermentation is a specific chemical reaction within the respiration cycle. It takes place when the cells do not have access to oxygen, a condition also known as anaerobic respiration.

• The process of fermentation generates far less energy than aerobic, or oxygen-based, respiration.

Fermentation allows glycolysis to continue.

• Fermentation is an anaerobic process.– occurs when oxygen is not available for cellular respiration– does not produce ATP

• Fermentation allows glycolysis to continue making ATP when oxygen is unavailable.

• Fermentation allows glycolysis to continue making ATP when oxygen is unavailable.

• Lactic acid fermentation occurs in muscle cells.– glycolysis splits glucose into two pyruvate molecules– pyruvate and NADH enter fermentation– energy from NADH converts pyruvate into lactic acid– NADH is changed back into NAD+

• NAD+ is recycled to glycolysis

Fermentation and its products are important in several ways.

• Alcoholic fermentation is similar to lactic acid fermentation.– glycolysis splits glucose and the products enter fermentation

– energy from NADH is used to split pyruvate into an alcohol and carbon dioxide

– NADH is changed back into NAD+

– NAD+ is recycled to glycolysis

• Fermentation is used in food production.– yogurt

– cheese

– bread

Can be useful in post mortem evaluation

• When people exercise, they often use up oxygen faster than it can be restored. For this reason, muscle cells are capable of engaging in temporary anaerobic respiration.

• When adequate oxygen is not available due to exercising, muscle cells ferment, producing lactic acid. Lactic acid then builds in the muscles, causing cramps, soreness and fatigue.

• After death the lactic acid begins to ferment, especially in the fatty areas of the body

Why is it important to Forensic Science?

• Butyric acid is a fatty acid occurring in the form of esters in animal fats---it breaks down in 20-50 days resulting in decomposition

Why is it important to Forensic Science?

• Forensic Toxicology is the branch of science which determines the absence or presence of drugs and their metabolites, chemicals such as ethanol and other volatile substances, and other drugs of abuse in human fluids and tissues.

• The presence of these substances may also be evaluated to determine their role as a contributory factor in the cause and manner of death or their role in modifying human performance or behavior.

Post Mortem Breakdown

• the analysis of alcohol in stomach contents is a common practice in forensic toxicology to compare with blood-alcohol concentration thus providing a clue as to whether the person had died shortly after drinking alcohol.