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What is the key difference between Type I and Type II restriction enzymes?

Answer: Type II cuts within or near recognition site; Type I cuts away from it.

  • A Type I cuts within the recognition site; Type II cuts elsewhere
  • B Type II cuts within or near recognition site; Type I cuts away from it
  • C Type I requires ATP; Type II mainly requires Mg<sup>2+</sup> instead
  • D Type II works mainly on RNA substrates specifically

Correct answer: B. Type II cuts within or near recognition site; Type I cuts away from it

Explanation: Type II restriction enzymes (used in genetic engineering) cut within or very close to their recognition sequence, producing predictable fragments. Type I enzymes cut far from their recognition site, making them impractical for cloning.

Enzyme Kinetics: Rate vs Substrate Concentration[Substrate]Reaction rateVmaxKm½VmaxCurve flattens at high [S]: ALL enzyme active sites are occupied (saturation)

As substrate concentration rises, reaction rate increases steeply at first, then plateaus at Vmax once every enzyme molecule is working at full capacity; Km is the substrate concentration giving half-maximal rate, and a LOWER Km means the enzyme reaches that rate with less substrate (higher affinity).

Concept context

Carbohydrates, proteins, lipids, nucleic acids, and enzyme kinetics. Essential foundation for understanding metabolism.

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