Ch.4 Enzymes and metabolism Flashcards
Metabolism is divided into _________ and ________.
catabolism (分解代謝); anabolism (合成代謝)
Metabolism is the sum of the ________ reactions that takes place in an organism.
chemical
Catabolism is the _______-_____ reactions in an organism.
breaking-down
Anabolism is the _______-___ reactions in an organism.
building-up
Energy is released in { catabolism / anabolism }.
catabolism
Enzymes are biological c_______.
catalysts (催化劑)
Enzymes speed up chemical reactions in organisms by lowering the _________ energy of the reactions.
activation
Enzymes speed up chemical reactions in organisms by lowering the _________ energy of the reactions.
activation (活化)
T/F: Each substrate has an active site.
F.
Each enzyme has an active site.
Substrate(s) binds to the active site of enzyme to form an ______-________ complex.
enzyme-substrate
T/F: Formation of enzyme-substrate complex greatly highers the activation energy of the reaction.
F
The formation of enzyme-substrate complex greatly lowers the activation energy of the reaction.
After binding with enzyme molecule, the substrate(s) is converted into _______(s), which then dissociate from the active site.
product(s) (生成物)
T/F: Enzyme actions are specific.
T
Each enzyme has a ______ active site, which has a specific ______. It only acts on substrates that can fit into its active site.
unique; shape
The specificity of enzyme actions can be explained by the ____-___-___ hypothesis.
lock-and-key
Enzymes are proteins. Their structures and hence their activity are easily affected by __________ and ___.
temperature; pH
Are enzymes reusable? Why?
Yes. Enzymes is released in its original form after reactions.
Enzymes are needed in relatively { large / small } amounts.
small
Enzyme activity is low when temperature is low. Explain why.
The kinetic energy of enzyme and substrate molecules is low. The molecules move slowly and the chance of them to collide with each other is low.
At low temperature, enzymes are inactive. The ______ energy of enzyme and substrate molecules is low.
kinetic
As temperature rises, both enzyme and substrate molecules have more kinetic energy. They ______ with each other more frequently. This increases the chance of forming enzyme-substrate complexes.
collide
At optimum temperature, enzyme activity reaches a { maximum / minimum }.
maximum
Enzymes work best at their ________ temperature.
optimum
At high temperatures, enzyme activity { increases / dereases }.
decreases
High temperatures cause a change in shape of the active site of the enzyme molecule. The enzyme is ________d.
denatured (變性)
The substrate can no longer fit into the active site of the denatured enzyme to form the enzyme-substrate complex. The enzyme loses its _______ ability permanently.
catalytic
At optimum pH, enzyme activity reaches a { maximum / minimum }.
maximum
Enzymes work best at their ________ pH.
optimum
At unsuitable pH, enzyme activity { increases / dereases }.
decreases
Unsuitable pH causes ___________ of the enzyme. The substrate can no longer fit into the active site of the enzyme. The enzyme loses its catalytic ability permanently.
denaturation
_________s are substances that decrease the activity of enzymes.
Inhibitors (催化劑)
Give examples of inhibitors.
Cyanide(氰化物), heavy metals, etc.
How are enzymes used in producing cheese?
Proteases(蛋白酶) coagulate milk.
How are enzymes used to produce fruit juice?
Pectinase(果膠酶) breaks down the pectin(果膠) in plant cell wall to increase the juice production. It also breaks down the pectin in the juice to make the juice looks clear.
How are enzymes used to produce liquid-centred chocolate?
Invertase(轉化酶) breaks down the sugars into more soluble forms.
How are enzymes used to produce biofuel (e.g. bioethanol)?
Cellulase(纖維素酶) breaks down the cellulose in crops into sugars to increase the biofuel production.
How are enzymes used to produce biodegradable(可生物降解的) plastic?
An enzyme extracted from a bacterium breaks down the plastic to shorten the time for a plastic bag to degrade.
How are enzymes used to produce meat tenderizers(鬆肉粉)?
Papain (木瓜酶) breaks down the proteins in meat to soften the meat.
How are enzymes used to produce biological washing powders?
Proteases and lipase(脂肪酶) break down the insoluble proteins and lipids in stains into soluble products.
How are enzymes used to produce cleansers(洗面乳)?
Papain breaks down dead cells in the skin.
How are enzymes used to produce stonewashed jeans(石磨藍牛仔褲)?
Cellulase breaks down the cellulose fibres of the jeans.
How are enzymes used to produce drugs?
Lysozyme(溶菌酶) breaks down the cell wall of certain bacteria to kill them.
Enzyme can speed up __________ reactions. This shortens production time and allows the mass production of products.
chemical
Many enzymes work at __________ conditions. This does not require extreme conditions, such as very high temteratures and pressures.
moderate (中性的)
Enzymes are _______ in action. This produces fewer unwanted products.
specific
Enzymes are ________ and are needed in small amounts only. This lowers the cost of production.
reusable
Enzymes are ________ to temperature and pH changes. They cannot be used if the production process involves a high temperature or an unsuitable pH.
sensitive
Enzymes are easily affected by _______s → all containers used in the production processes have to be clean to prevent the containers from being contaminated with them.
inhibitors
