Glycolysis and Fermentation

• The lecture covers glycolysis and fermentation.

Cellular Respiration

• Breathing facilitates gas exchange, ensuring cells have oxygen to extract energy from nutrients.
• Oxygen is involved in reactions that produce ATP from nutrients, which distributes energy in the organism.
• Cellular respiration includes glycolysis, the Krebs cycle, and the electron transport chain.

Glycolysis

• Glycolysis occurs in the cytosol and is an anaerobic process
• Glycolysis produces products that participate in the electron transport chain that requires oxygen
• Glycolysis can be divided into two phases: the investment phase and the yield phase.
• In the investment phase, glucose is phosphorylated to glucose-6-phosphate and then split into two molecules of glyceraldehyde-3-phosphate, consuming two ATP molecules
• The first five steps of glycolysis consume energy
• In the yield phase, two glyceraldehyde-3-phosphate molecules are converted into two pyruvate molecules and the production of 4 ATP molecules and two NADH.
• The yield phase regenerates molecules present in the cell, resulting in a net gain of energy for the glycolytic pathway.

Investment Phase Steps

• Glucose is transported into a cell and phosphorylated by ATP, forming glucose-6-phosphate
• Glucosio-6-phosphate undergoes rearrangement to form a molecule of fructose-6-phosphate
• Another molecule of ATP is used to add a second phosphate group to fructose-6-phosphate, which becomes fructose-l,6-diphosphate
• Fructose-1,6-diphosphate splits into two molecules of glyceraldehyde-3-phosphate, each with three carbon atoms and a phosphate group
• Glycolysis duplicates from this point forward
• Triose phosphate isomerase combines glyceraldehyde-3-phosphate, NAD, and a phosphate
• Gylceraldehyde-3-phosphate is oxidized by NAD, turning it into NADH and releasing an electron to be sent to the ETC
• The oxidation of glyceraldehyde-3-phosphate produces sufficient energy to attach a phosphate group to the main molecule, transforming it into 1,3-diphosphogylceric acid
• Two molecules of NADH are produced at this stage because the reactions are doubled

Recovery Phase Steps

• L'acido 1,3-difosfoglicerico loses one of its phosphate groups by converting into 3-phosphoglyceric acid. The reaction produces enough energy to combine with ADP, producing. Two molecules of ATP are made in this stage.
• L'acido 3-fosfoglicerico transforms into fosfoenolpiruvico acid that produces another ATP by trasferring a phosphate group to all'ADP. Two molecules of ATP are obtained.
• Fosfoglicerato mutasi removes phosphate in position 3 da una molecola di 2,3- generating 2-fosfoglicerato.
• The second to last reaction is like a dehydration 2-fosfoglicerato which creates fosfoenolpiruvato. This dehydration is catalysed by enolasi.
• In the last step, it is fosfoenolpiruvato that, by means of piruvato, Mg2+ dependent, is always idrolizzato with enolpiruvato. ATP is produced in the conversion stage piruvato.

Net Energy Yield

• 1 Glucose + 2 ATP (Phase I)
• 2 glyceraldehyde 3' phosphate → 2 x (2 ATP + 1 NADH) (Phase II) Total : 2 ATP + 2 NADH / 1 glucose

Fates of Pyruvate

• Pyruvate's fate depends on: type of organism, cellular compartment and aerobic or anaerobic conditions
• Citric acid Cycle
• Certain tissues and types of cells, the retina, the brain and the erythrocytes convert glucose into lactate even in aerobic conditions
• In some tissues of plants and in some invertebrates, protiists and microoganismi such as the beer yeast.
• Pyruvate can also have anabolic outcomes.

Ethanol Fermentation

• Some organisms convert pyruvate into ethanol and CO2 in anaerobic conditions via 2 enzymes in 2 consecutive steps.
• Piruvato decarbossilasi: irreversible decarbossilazione del piruvato ad acetaldeide e CO2.
• Tiamina pirofosfato (TPP) e ioni Mg2+ necessari per attività dell'enzima
• Alcol deidrogenasi: riduzione acetaldeide ad etanolo tramite coenzima NADH convertito a NAD and thus is regenerated stopping glycolisis
• The CO2 that is produced is released into the atmosphere.

Tiamina (Vitamina B1)

• Thiamin (Vitamin B1) can be found in foods of animal and plant origin.
• It is found in foods of plant form and animal form mainly as a mono- or diphosphate
• Particularly rich in this vitamin are legumes, germ and the pericarp of cereals. In animal foods, the highest concentrations are in the liver, kidney, brain and intestine
• Another important source thiamine is also the brewer's yeast

Alcohol Fermentation and Foods

• Ethanol production is used as a solvent or fuel
• Production of beverages like wine, and beer etc
• Production of distilled beverages like liquors.

Lactic Fermentation

• It is activated from yeasts and bacteria in absence of oxygen, but often even by muscular tissues of the vertebrates as a result of an excessive muscular affaticamento.
• It is just l'acido lattico, in fact, to provoke that sensation of indolenzimento when riprendiamo l'attività physical after an excessive effort or when we are trying to work too much i nostri muscoli.

Features of Lactic Fermentation

• It happens via a unique process that doesn't always cause a C02 carbon loss.
• It's a bacteria that utilizes enzymes to create lactate that is often utilized for the fermentation of yogurt
• Agents involved are Streptococcus and Lactobacillus, creating sugar into lactatic acid

Yogurt

• The transformations carried out by bacteria in fermentation involve changing the physical, chemical, bacteriological, organoleptic and nutritional properties of the original milk product.
• Bacteria use the lactose consumed to multiply, and eventually produce lactic acid.
• Lactic acid is also responsible for reducing the pH of the milk that causes the caseins to condense, creating the texture associated with yogurt.
• Yogurt is a probiotic containing live bacteria that is beneficial for the human body.

Lattofermented Vegetables

• Lactic fermentation is a method of preserving different harvested vegetables
• Lactic bacteria is critical to the process
• Cut up vegetables are immersed in water and sealed in an airtight container
• Sale breaks down the cell and fluids are extracted
• The bacteria then transform the vegetable's cabohydrates into lactic acid and carbon dioxide, and give the vegetable a mild taste
• The bacteria stunts growth of bacteria, preserving the vegetable
• Lattofermented vegetables have a high health value
• In fact, vitamins which often are lost in the food creation process now are preserved during fermentation, preserving a natural flora within the product
• Commonly preserved lactic vegetables are cabbages.

This lecture discusses cellular respiration, including glycolysis and fermentation. Glycolysis occurs in the cytosol and is divided into two phases: the investment phase and the yield phase. It is an anaerobic process that produces products for the electron transport chain.