细胞呼吸中的氧化还原

一种物理灭菌方法，通过将液体和气体中的微生物通过孔径足够小的过滤器来去除微生物。除菌过滤的常见孔径为 0.22 微米 (µm)，可有效去除大多数细菌。该技术并非杀死微生物，而是以物理方式将它们分离，因此非常适合热不稳定溶液。

过电位是指半反应热力学确定的还原电位与实验观察到的氧化还原电位之间的电位差（电压）。它代表克服活化能垒使电极反应以显著速率进行所需的额外能量。它是所有电解过程能量效率的关键因素。

In 1921, Frederick Banting and Charles Best, under John Macleod's direction at the University of Toronto, isolated insulin from canine pancreatic extracts. Biochemist James Collip then developed a purification process, making the extract safe for human use. This discovery transformed type 1 diabetes from a fatal disease into a manageable condition, earning Banting and Macleod the 1923 Nobel Prize.

电化学电位是生命的基础，它驱动着跨细胞膜的细胞过程。离子泵主动产生浓度梯度，而离子通道的选择性通透性则产生电位（膜电位）。由此产生的电化学梯度决定了离子的被动流动，这对于神经信号传导（动作电位）、肌肉收缩以及线粒体中的细胞能量产生（ATP合成）至关重要。

The Calvin cycle, or light-independent reactions, uses the ATP and NADPH produced during the light-dependent stage to convert inorganic carbon dioxide into organic sugar molecules. This process occurs in the stroma of the chloroplast. The key enzyme, RuBisCO, catalyzes the first step: the fixation of [latex]CO_2[/latex] into an organic molecule, initiating a cycle that produces carbohydrates.

Translation is the biological process in which ribosomes in the cytoplasm or endoplasmic reticulum synthesize proteins. It follows transcription, where the DNA sequence is copied into a messenger RNA (mRNA) molecule. During translation, the ribosome reads the mRNA sequence in three-nucleotide units called codons, and with the help of transfer RNA (tRNA), assembles the corresponding amino acid chain.

一种使用高温高压饱和蒸汽对设备和用品进行灭菌的方法。典型的灭菌周期为121°C (250°F)，压力高于大气压100 kPa (15 psi)，持续15分钟。这种高温和湿气的结合能有效地使蛋白质和酶变性，杀死所有微生物，包括顽固的细菌孢子。

A peptide bond is a covalent chemical bond formed between two amino acid molecules. It links the carboxyl group ([latex]-COOH[/latex]) of one amino acid to the amino group ([latex]-NH_2[/latex]) of another, releasing a molecule of water in a dehydration synthesis reaction. This amide-type bond is fundamental to forming polypeptide chains, the basis of protein primary structure.

D 值是在特定温度下杀死 90%（或减少一个对数值）目标微生物群所需的时间。它是热杀菌中的一个关键参数，可量化微生物对热的抵抗力。例如，如果 [latex]10^6[/latex] 孢子数量的 D 值为 2 分钟，则需要 2 分钟才能将其减少到 [latex]10^5[/latex]。

Protein denaturation is the process in which a protein loses its native three-dimensional structure. This disruption of secondary, tertiary, and quaternary structures is caused by external stressors such as heat, extreme pH, organic solvents, or radiation. While the primary sequence of amino acids remains intact, the loss of shape results in the loss of the protein's biological function.

一种使用环氧乙烷气体的低温化学灭菌方法。该方法可有效灭菌塑料、电子设备和光学仪器等热敏性和湿敏性材料。该过程涉及烷基化，其中环氧乙烷会破坏微生物的DNA和蛋白质，从而阻止其复制。该方法需要严格控制气体浓度、温度、湿度和暴露时间。

细胞毒性是指物质或细胞对其他细胞具有毒性的特性。细胞毒性药物可通过坏死（细胞膜失去完整性，导致细胞溶解和炎症）或凋亡（一种受控的程序性细胞死亡过程）诱导细胞死亡。这与细胞抑制剂不同，细胞抑制剂仅抑制细胞分裂，而不会直接导致细胞死亡。

The alpha-helix ([latex]\alpha[/latex]-helix) is a common secondary structure motif in proteins. It is a right-handed coiled conformation in which every backbone N-H group donates a hydrogen bond to the backbone C=O group of the amino acid located four residues earlier ([latex]i+4 \rightarrow i[/latex] hydrogen bonding). This regular pattern pulls the polypeptide chain into a helical shape.

Insulin is synthesized in pancreatic beta cells as a single-chain precursor called proinsulin. In the endoplasmic reticulum, proinsulin folds and forms its disulfide bonds. It is then transported to the Golgi apparatus and packaged into secretory granules, where proteases (prohormone convertases PC1/3 and PC2, and carboxypeptidase E) cleave it into mature insulin and a connecting peptide, C-peptide.