Ch. 4a Metabolism & Enzymes [代謝作用 和 ]
Metabolism [代謝作用]: all the chemical reactions taken place inside the living organisms.
Metabolic processes: eg. photosynthesis, respiration, etc. [代謝過程: 例如 光合作用, 呼吸作用] Types [種類] - catabolism [分解代謝] - breaking down of complex organic molecules into simple molecules. (eg. respiration ) [分解複雜有機分子成為簡單分子 (例如: 呼吸作用)]
- anabolism [組成代謝] - building up of complex organic molecules from simple molecules.
(eg. photosynthesis ) [由簡單分子建造複雜有機分子] Control of metabolism (metabolic rate): [控制代謝過程 (代謝速率)] - it can be controlled / speed up by enzymes [能夠控制/加快它的速度] - the rate would be too slow to occur if no enzymes are present. ( die. [如果沒有, 代謝速率便會太慢]
- working mechanism [運作機制]
- each enzyme has an active site [每個最小有一個活性部位] - each active site can only allow specific substrate to fit on [每個活性部位只容許裝入特別的基質] - the enzyme and substrate molecules combine to form enzyme-substrate complex [和基質分子結合形成底物複合物]
- the product form and then enzyme is free to attach the other substrate molecules (therefore it can be reused) [形成產品, 然後便可自由地黏附其他基質分子 (所以它能夠再用)] - this mechanism is called lock and key hypothesis (NOT: key and lock hypothesis). [這個機制叫鎖鑰假設 (不要寫成: 鑰鎖假設)]
- Properties of enzymes [的特性]:
- biological catalyst ( it can speed up/regulate chemical reactions) [生物催化劑(它可以加快/調節化學反應)] - it is protein in nature [它的本質是蛋白質] - it is specific in action. ( 1 enzyme will catalyse only 1 reaction) [它有非常專一性(一種只催化一種反應)] (the special active site of a particular enzyme can only allow substrates with a particular shape to fit on) [每個的特殊活性部位, 只可以裝入有特殊形狀的基質] - it can catalyse reversible reaction in both directions. [它能夠向兩個方向催化可逆過程] - it is reusable, only a small amount is required. [它是可再用的, 因此只需要用小量]
- factors affecting enzymatic activities: temperature & pH [影響活性的因素: 溫度和酸鹼度] - factors affecting the rate of enzymatic reaction: temperature, pH, substrate concentration, enzyme concentration [影響反應速率的因素: 溫度, 酸鹼度, 基質濃度, 濃度]
- temperature [溫度]:
- low temperature: the enzyme molecules have less energy to work.
the enzyme is inactive. (NOT: denatured)
[低溫: 分子有較小能量去工作, 是不活躍 (不要寫成: 變性)] - higher temperature: the enzyme is active. [較高溫度: 是活躍的] - optimum temperature: the enzyme becomes most active. [最適溫度: 變成最活躍] different enzymes have different optimum temperature. [不同有不同的最適溫度]
(37oC is only our body temperature. It is not necessarily the optimum temperature of a particular enzyme. They usually lie between 45-50oC) [37oC只是我們的體溫, 它不一定是某一隻的最適溫度] - high temperature (higher than optimum) ( enzyme is denatured. [高溫(高過最適溫度) (已變性] (NOT: dead/killed) (use “denatured” instead of “destroyed”.)
[不要寫成: 死亡/被殺死] [用 “變性”, 而不用 “破壞”]
- pH: (NOT: PH) [酸鹼度]
- optimum pH (the most suitable pH for the enzyme). [最適酸鹼度] - different enzymes active in different optimum pH. [不同有不同最適酸鹼度] - pH other than optimum pH can inactivate the enzymes. (i.e. enzymes are inactive) [其他酸鹼度可以使不活躍] - too extreme pH can denature the enzymes. (Usually not consider in HKCEE) [太極端的酸鹼度可以使變性 (中學會考通常不會考慮: 酸鹼度使變性)]
True or false ?
- Liver does not contain any enzyme. (Liver secretes bile that does not contain any enzyme.) [真或假? 肝臟不含有任何 (因肝臟分泌膽汁, 而膽汁沒有任何)] Where can we find enzymes [我們可以在何處找到]: 1. in our body? ( in every living cell. [在我們體內? ( 在每個活的細胞內]
2. in daily life?
( eg. washing powder, as meat tenderizer [在日常生活中? ( 例如: 洗衣粉, 鬆肉粉]
(Relate the application of enzymes in industrial processes and commercial products.)[Small project] [敘述在工業過程和商業產品的應用] [小型探究活動]
Example of enzyme: catalase - in every cell. [的例子: 過氧化氫 – 在每種細胞] (hydrogen peroxide produced is a toxic byproduct of...
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