📚 Biotechnology Key Points | 生物技术考点精讲
Biotechnology uses living organisms or biological systems to make useful products. For IGCSE AQA Biology, you need to understand traditional methods like fermentation and bread-making, as well as modern techniques such as genetic engineering. This guide covers all the key processes, from microorganisms in food production to the industrial production of medicines and fuels.
生物技术利用生物体或生物系统制造具有实用价值的产品。对于IGCSE AQA生物课程，你需要掌握发酵、面包制作等传统方法，以及基因工程等现代技术。本指南涵盖所有关键过程，从微生物在食品生产中的作用到药品和燃料的工业化生产。
1. What is Biotechnology? | 什么是生物技术？
Biotechnology is the application of living organisms, cells, or biological molecules to produce goods and services for human life. It can range from ancient practices like making bread to cutting‑edge gene editing.
生物技术是应用生物体、细胞或生物分子来生产对人类生活有益的产品和服务。它的范围很广，从制作面包这种古老的做法到尖端的基因编辑都属于生物技术。
At IGCSE, we focus on how microorganisms (bacteria and fungi) are used in food production and industry, and how genetic modification can improve crops and produce medicines.
在IGCSE阶段，我们主要关注微生物（细菌和真菌）如何用于食品生产和工业，以及基因改造如何改良作物和生产药物。
2. Traditional vs Modern Biotechnology | 传统与现代生物技术
Traditional biotechnology uses naturally occurring microorganisms without altering their DNA. Examples include brewing beer, baking bread, and making cheese.
传统生物技术利用天然的微生物而不改变其DNA，例如酿造啤酒、烤制面包和制作奶酪。
Modern biotechnology often involves genetic engineering, where the DNA of an organism is modified to give it a new characteristic. Examples include bacteria producing human insulin and genetically modified crops resistant to pests.
现代生物技术通常涉及基因工程，即改造生物的DNA使其获得新性状，例如生产人胰岛素的细菌和抗害虫的转基因作物。
3. Fermentation Basics | 发酵的基础知识
Anaerobic respiration in microorganisms is the foundation of many biotechnological processes. Yeast and some bacteria break down glucose without oxygen, producing ethanol, carbon dioxide, or lactic acid.
微生物的无氧呼吸是许多生物技术过程的基础。酵母和某些细菌在无氧条件下分解葡萄糖，产生乙醇、二氧化碳或乳酸。
The word equation for fermentation by yeast is: glucose → ethanol + carbon dioxide. This reaction releases energy and is vital for making alcoholic drinks and bread rise.
酵母发酵的文字方程式为：葡萄糖 → 乙醇 + 二氧化碳。这个反应释放能量，对制造酒精饮料和面包发酵至关重要。
4. Making Yogurt | 制作酸奶
Yogurt is produced by the bacterial fermentation of milk. The milk is first pasteurised to kill any harmful microorganisms, then cooled and inoculated with a starter culture containing Lactobacillus bacteria.
酸奶是通过牛奶的细菌发酵制成的。首先对牛奶进行巴氏消毒以杀死有害微生物，然后冷却并接种含有乳酸菌的发酵剂。
The bacteria respire anaerobically, converting lactose (milk sugar) into lactic acid. The lactic acid lowers the pH, causing milk proteins to coagulate and thicken the mixture into yogurt.
这些细菌进行无氧呼吸，将乳糖（牛奶中的糖分）转化为乳酸。乳酸降低pH值，使牛奶蛋白质凝固，混合物变稠成为酸奶。
The sour taste and thick texture come from the lactic acid, and the low pH also helps preserve the yogurt by inhibiting the growth of other spoilage bacteria.
酸味和浓稠的质地来自乳酸，低pH值还能抑制其他腐败菌的生长，有助于酸奶的保存。
5. Making Bread | 制作面包
Bread dough is made from flour, water, sugar, and yeast. The yeast respires aerobically at first, using up any oxygen, producing carbon dioxide and water.
面团由面粉、水、糖和酵母制成。酵母最初进行有氧呼吸，消耗面团中的氧气，产生二氧化碳和水。
Once oxygen runs out, the yeast switches to anaerobic respiration, producing ethanol and carbon dioxide. The carbon dioxide gas gets trapped in the dough, forming bubbles that cause the dough to rise.
氧气耗尽后，酵母转为无氧呼吸，产生乙醇和二氧化碳。二氧化碳气体被困在面团中，形成气泡使面团膨胀发酵。
During baking, the high temperature kills the yeast and evaporates the ethanol. The holes left by gas bubbles give bread its light, spongy texture.
烘烤过程中，高温杀死酵母并蒸发掉乙醇。气泡留下的孔洞使面包具有轻盈、松软的质地。
6. Making Beer and Wine | 酿造啤酒与葡萄酒
Alcoholic drinks are produced by the anaerobic respiration of yeast on a sugar source. For wine, the sugar comes directly from grape juice. For beer, starch from barley grains is broken down into sugars before fermentation.
酒精饮料是通过酵母对糖源进行无氧呼吸生产的。葡萄酒的糖直接来自葡萄汁；啤酒则需先将大麦中的淀粉分解为糖再发酵。
The reaction is carried out in large fermentation vessels under controlled temperature and pH to optimise yeast activity. Carbon dioxide is released and ethanol accumulates in the liquid.
反应在大型发酵罐中进行，控制温度和pH值以优化酵母活性。释放出的二氧化碳逸出，乙醇在液体中积累。
When the sugar is used up or the alcohol concentration becomes too high for the yeast to survive, fermentation stops. The product is then filtered and purified.
当糖耗尽或酒精浓度过高导致酵母无法存活时，发酵停止。产品随后被过滤和纯化。
7. Biofuels | 生物燃料
Biofuels like bioethanol and biogas are produced using microorganisms. Bioethanol is obtained by fermenting sugars from crops such as maize or sugar cane, using yeast.
生物乙醇和沼气等生物燃料是利用微生物生产的。生物乙醇是通过酵母发酵来自玉米或甘蔗等作物的糖获得的。
The ethanol is distilled and can be blended with petrol to reduce fossil fuel use. Biogas, mainly methane, is produced by anaerobic digestion of organic waste such as animal manure and food scraps, carried out by bacteria in a digester.
乙醇经过蒸馏后可与汽油混合，以减少化石燃料的使用。沼气主要成分是甲烷，由细菌在沼气池中对动物粪便和食物残渣等有机废物进行厌氧消化而产生。
Using biofuels is considered carbon‑neutral because the carbon dioxide released during combustion was recently taken in by the plants through photosynthesis.
使用生物燃料被认为是碳中性的，因为燃烧时释放的二氧化碳是植物近期通过光合作用吸收的。
8. Penicillin Production | 青霉素的生产
Penicillin is an antibiotic produced by the fungus Penicillium. The process is carried out in large industrial fermenters under carefully controlled conditions.
青霉素是由青霉菌产生的一种抗生素。生产过程在大型工业发酵罐中进行，条件受到严格控制。
The fungus is grown in a nutrient medium containing sugar and other essential nutrients. Oxygen and temperature are maintained at optimum levels, and pH is kept slightly acidic. Penicillin begins to accumulate after several days.
真菌在含有糖和其他必需营养素的培养基中生长。维持最适氧气和温度，pH值保持在微酸性。数天后青霉素开始积累。
The penicillin is then extracted, purified, and crystallised for medical use. Aseptic techniques are vital to prevent contamination by other microorganisms.
然后提取、纯化并结晶青霉素供医疗使用。无菌技术对于防止其他微生物污染至关重要。
9. Mycoprotein | 真菌蛋白
Mycoprotein is a protein‑rich food made from the fungus Fusarium. It is grown in continuous fermentation using glucose syrup as the energy source, with air supplied for aerobic respiration.
真菌蛋白是一种由镰孢菌制成的富含蛋白质的食物。它在连续发酵中生长，使用葡萄糖浆作为能量来源，并通入空气进行有氧呼吸。
The biomass is harvested, heat‑treated to remove bitter tastes, and then textured and flavoured to produce meat substitutes. It is high in protein and fibre, low in saturated fat, and has a smaller environmental footprint than meat production.
收获的菌丝体经过热处理去除苦味，再进行质构和调味制成肉类替代品。真菌蛋白富含蛋白质和纤维、饱和脂肪含量低，而且比肉类生产消耗更少环境资源。
10. Using Enzymes in Industry | 工业中酶的使用
Enzymes from microorganisms are widely used in industry because they catalyse specific reactions under mild conditions, saving energy and reducing by‑products.
来自微生物的酶被广泛用于工业，因为它们能在温和条件下催化特定反应，节省能源并减少副产物。
Proteases are added to biological washing powders to break down protein stains like blood and egg. Amylases break down starch stains, and lipases break down fats and oils.
蛋白酶被添加到生物洗衣粉中，分解血迹、蛋渍等蛋白质污渍。淀粉酶分解淀粉类污渍，脂肪酶分解油脂。
Isomerase converts glucose into fructose, which is sweeter, so less can be used in slimming foods. Pectinase breaks down pectin in fruit juice, increasing yield and clarity.
异构酶将葡萄糖转化为果糖，果糖更甜，因此低热量食品中用量可减少。果胶酶分解果汁中的果胶，提高出汁率和澄清度。
11. Genetic Engineering in Biotechnology | 生物技术中的基因工程
Modern biotechnology allows genes to be transferred from one organism to another. Bacteria can be genetically modified to produce human insulin, which is used by diabetics to control blood glucose levels.
现代生物技术可以将基因从一个生物体转移到另一个。细菌经过基因改造可生产人胰岛素，糖尿病患者用它来控制血糖水平。
The process involves isolating the human insulin gene, inserting it into a bacterial plasmid, and then introducing the plasmid into the bacterium. The bacteria then multiply in fermenters and secrete insulin, which is harvested and purified.
该过程包括分离人胰岛素基因，将其插入细菌质粒，然后将质粒导入细菌。细菌在发酵罐中繁殖并分泌胰岛素，再对胰岛素进行收集和纯化。
This method produces large quantities of pure human insulin that do not cause allergic reactions, unlike insulin extracted from pigs or cows.
这种方法可大量生产高纯度人胰岛素，且不会引起过敏反应，与从猪或牛提取的胰岛素不同。
12. Selective Breeding vs Genetic Modification | 选择性育种与基因改造的对比
Selective breeding involves choosing parent organisms with desired traits and breeding them over many generations. It relies on natural genetic variation and does not directly change DNA.
选择性育种是选择具有所需性状的亲本，经过多代繁殖后保留优良性状。它依赖自然遗传变异，不直接改变DNA。
Genetic modification (GM) directly alters an organism’s genome by inserting a specific gene from another species. This is much faster and allows introduction of completely new traits, such as herbicide resistance in crops.
基因改造（GM）通过插入来自另一物种的特定基因来直接改变生物的基因组。这种方法速度更快，还能赋予生物全新的性状，例如作物的抗除草剂特性。
IGCSE exam questions often ask you to compare these two processes, considering speed, precision, and ethical concerns.
IGCSE考题常要求比较这两种过程，从速度、精确度和伦理问题等角度进行分析。
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