Biotechnology Revision Notes

When oxygen is absent, yeast cells break down glucose anaerobically.

This process produces ethanol and carbon dioxide as by-products while releasing energy for yeast survival.

• Glucose is converted without oxygen.
• Ethanol and CO2 are produced.
• Energy is released for yeast.

The ethanol produced by yeast is collected and purified.

Ethanol serves as a renewable biofuel, offering an alternative to fossil fuels and reducing environmental impact.

• Ethanol is harvested from fermentation.
• Used as sustainable energy source.

Anaerobic respiration allows yeast to survive in oxygen-poor environments.

It enables continuous energy production and ethanol generation for biofuel applications.

• Supports yeast survival without oxygen.
• Enables biofuel production.

Inside bread dough, oxygen is limited, so yeast respires anaerobically.

Yeast breaks down sugars to release energy, producing carbon dioxide and ethanol as by-products.

• Limited oxygen in dough.
• Sugars broken down anaerobically.
• Energy released for yeast growth.

Carbon dioxide gas forms bubbles trapped in the dough.

These bubbles expand the dough, causing it to rise and giving bread a light texture.

• CO2 gas bubbles form in dough.
• Dough expands and rises.

Ethanol is produced alongside carbon dioxide during anaerobic respiration.

Most ethanol evaporates during baking and does not remain in the bread.

• Ethanol produced as by-product.
• Evaporates during baking process.

Pectin is a polysaccharide found in the cell walls of fruits, acting like a glue that holds the cells tightly together. This structural role maintains the firmness and integrity of the fruit tissue.

• Pectin binds fruit cells together.
• It contributes to the fruit's firmness and texture.

Pectinase is an enzyme that specifically breaks down pectin molecules. By digesting pectin, pectinase loosens the connections between fruit cells, causing them to separate more easily.

• Pectinase targets and breaks down pectin in cell walls.
• This enzymatic action separates fruit cells.

When pectinase breaks down pectin, juice can be released more efficiently from the fruit cells. This increases the amount of juice extracted and improves the clarity of the juice by reducing suspended pectin particles that cause cloudiness.

• More juice is extracted due to cell separation.
• Juice clarity improves as pectin particles are reduced.
• Overall juice yield and quality are enhanced.

Biological washing powders include enzymes such as proteases, lipases, and amylases. Each enzyme targets a specific type of stain: proteases break down protein stains like blood or egg; lipases break down fat or grease stains; amylases break down carbohydrate stains such as starch.

• Proteases digest protein-based stains.
• Lipases digest fat-based stains.
• Amylases digest carbohydrate-based stains.

Enzymes catalyze the breakdown of large, complex molecules in stains into smaller, soluble molecules. These smaller molecules dissolve in water and are easily washed away, improving stain removal.

• Enzymes speed up chemical reactions breaking down stains.
• Complex molecules become smaller and soluble.
• Smaller molecules are removed easily during washing.

Because enzymes work efficiently at lower temperatures, biological powders allow effective cleaning without hot water, saving energy and protecting fabric quality. Enzymes also improve stain removal compared to non-biological powders.

• Effective stain removal at lower temperatures.
• Energy savings due to reduced heating.
• Gentler on fabrics, extending their lifespan.

Lactose is a disaccharide sugar naturally present in milk. Some people lack sufficient lactase enzyme to digest lactose, leading to symptoms like bloating and cramps after consuming milk.

• Lactose is the main sugar in milk.
• Lactose intolerance results from low lactase levels.
• Undigested lactose causes digestive discomfort.

Lactase is an enzyme that splits lactose into two simpler sugars: glucose and galactose. These monosaccharides are easier to digest and absorb in the intestine.

• Lactase breaks lactose into glucose and galactose.
• Simpler sugars are digestible by lactose-intolerant individuals.

Adding lactase to milk breaks down lactose before consumption, reducing lactose content. This process produces lactose-free milk, allowing lactose-intolerant people to enjoy milk without discomfort.

• Lactase is added to milk during processing.
• Lactose is converted to glucose and galactose.
• Lactose-free milk is suitable for lactose-intolerant consumers.

Fermenters are large vessels designed to maintain optimal conditions such as temperature, pH, oxygen levels, and nutrient supply. These conditions support rapid growth and metabolism of microorganisms like bacteria and fungi.

• Provide controlled environment for microbial growth.
• Maintain ideal temperature, pH, oxygen, and nutrients.
• Enable large-scale cultivation of microorganisms.

Bacteria and fungi grown in fermenters produce useful products: genetically modified bacteria produce insulin for diabetes treatment; fungi produce penicillin, an antibiotic; and certain fungi are cultured to produce mycoprotein, a protein-rich food substitute.

• Insulin produced by bacteria.
• Penicillin produced by fungi.
• Mycoprotein produced by fungi as a meat substitute.

Controlled conditions maximize microbial growth and product yield, allowing consistent, cost-effective mass production of valuable substances for medical and food applications.

• Optimized growth conditions increase efficiency.
• Mass production meets demand for medicines and food.
• Consistent product quality and safety.

Microorganisms have an optimum temperature range for enzyme activity and growth. Too high temperatures can denature enzymes and kill microbes; too low temperatures slow metabolism. Maintaining the correct temperature ensures efficient fermentation.

• Temperature affects enzyme activity and microbial growth rate.
• High temperatures can denature enzymes and kill microbes.
• Low temperatures slow fermentation.

Enzymes function best within specific pH ranges. Controlling pH by adding acids or alkalis keeps the environment suitable for microbial enzymes and growth, preventing reduced fermentation efficiency.

• pH affects enzyme shape and activity.
• Maintaining optimum pH supports microbial health.
• pH is adjusted by adding acids or alkalis.

Some fermentations require oxygen (aerobic), while others do not (anaerobic). Controlling oxygen supply ensures microorganisms use the correct metabolic pathways for product formation.

• Aerobic microbes need oxygen for respiration.
• Anaerobic microbes require oxygen-free conditions.
• Oxygen levels are adjusted accordingly.

Microorganisms need nutrients like sugars and minerals for energy and growth. Continuous supply supports metabolism and product synthesis during fermentation.

• Nutrients provide energy and building blocks.
• Lack of nutrients slows or stops fermentation.
• Nutrients are supplied continuously or in batches.

Waste products such as alcohol or acids can accumulate and inhibit microbial activity. Removing or diluting waste prevents toxicity and maintains fermentation efficiency.

• Waste buildup can be toxic to microbes.
• Waste removal prevents inhibition of growth.
• Methods include continuous removal or dilution.