krit.club logo

Biotechnology and Genetic Engineering - Biotechnology and yeast

Grade 12IGCSEBiology

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

•

Biotechnology is the application of biological organisms, systems, or processes to manufacturing and service industries. It often utilizes microorganisms like bacteria and fungi (yeast) because they are easy to grow, reproduce rapidly, and can produce a wide range of products.

•

Yeast (SaccharomycesSaccharomyces cerevisiaecerevisiae) is a single-celled fungus that is vital in biotechnology due to its ability to perform anaerobic respiration, also known as fermentation.

•

In bread making, yeast is mixed with dough. The yeast respires using the sugars in the dough, releasing CO2CO_2 bubbles which get trapped and cause the dough to rise. The ethanol produced evaporates during baking.

•

For ethanol production (biofuel), yeast ferments sugars from crops like sugarcane or maize. The reaction is C6H12O6→2C2H5OH+2CO2C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2. The ethanol is then distilled and used as a renewable energy source.

•

Enzymes are a major part of biotechnology. Pectinase is used to break down pectin in fruit cell walls to increase juice yield and clarity. Proteases and lipases are used in biological washing powders to break down protein and fat-based stains at lower temperatures, typically around 40∘C40^{\circ}C.

•

Lactase is used to produce lactose-free milk by breaking down the disaccharide lactose into the monosaccharides glucose and galactose: C12H22O11+H2O→C6H12O6+C6H12O6C_{12}H_{22}O_{11} + H_2O \rightarrow C_6H_{12}O_6 + C_6H_{12}O_6.

📐Formulae

C6H12O6→2C2H5OH+2CO2C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2

Glucose→Ethanol+Carbon Dioxide\text{Glucose} \rightarrow \text{Ethanol} + \text{Carbon Dioxide}

C12H22O11(lactose)+H2O→C6H12O6(glucose)+C6H12O6(galactose)C_{12}H_{22}O_{11} (\text{lactose}) + H_2O \rightarrow C_6H_{12}O_6 (\text{glucose}) + C_6H_{12}O_6 (\text{galactose})

💡Examples

Problem 1:

Calculate the volume of CO2CO_2 gas produced if a batch of yeast ferments 180g180g of glucose at STP, given the molar mass of glucose is 180g/mol180g/mol and 11 mole of gas occupies 22.4dm322.4dm^3 at STP.

Solution:

  1. Find moles of glucose: n=180g180g/mol=1 moln = \frac{180g}{180g/mol} = 1\text{ mol}.
  2. Use the stoichiometry from the equation C6H12O6→2C2H5OH+2CO2C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2. 11 mole of glucose produces 22 moles of CO2CO_2.
  3. Calculate volume: V=2×22.4dm3=44.8dm3V = 2 \times 22.4dm^3 = 44.8dm^3.

Explanation:

According to the balanced chemical equation for anaerobic respiration in yeast, every mole of glucose yields two moles of carbon dioxide. By applying the molar gas volume constant at STP, we find the total gas released.

Problem 2:

Why are biological washing powders containing enzymes more effective than non-biological ones for removing organic stains at 35∘C35^{\circ}C?

Solution:

Biological washing powders contain enzymes like proteases (for protein stains) and lipases (for fats). At 35∘C35^{\circ}C, which is close to the optimum temperature for many enzymes (usually 37∘C37^{\circ}C to 40∘C40^{\circ}C), the enzymes act as biological catalysts to speed up the hydrolysis of large, insoluble molecules into small, soluble ones.

Explanation:

Enzymes lower the activation energy required for the breakdown of stains. Without enzymes, much higher temperatures would be needed to achieve the same cleaning effect, which could damage certain fabrics.

Biotechnology and yeast - Revision Notes & Key Diagrams | IGCSE Grade 12 Biology