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1.5 Enzymes ⓵→❶


Introduction to enzymes

Photosynthesis is a core JC2 topic in H2 BIO A levels. It comprises the light dependent reaction and Calvin cycle. These processes occur in the thylakoids and stroma of the chloroplast predominantly found in plant mesophyll cells. Depending on the type of plant (C3, C4, CAM), photosynthesis may differ. But the outcome remains the same, eventually producing glucose and storage in the form of starch.
This topic is an important prerequisite for climate change. Also, it builds upon the foundation of biomolecules.

Materials for enzymes

Phrasing errors

  • Increase in kinetic energy of enzymes/particles results in more collisions per unit time.

Exam tips

  • Active site (enzymes ONLY) vs binding site for the rest of the proteins.
  • There is a difference between activation energy and free energy of enzymes.
  • For proteins that can withstand high temperature, mostly due to disulphide bonds.
  • Highlight the bonds btw R groups affected due denaturation by high temperature and/or pH.
  • Denaturation have 2 meanings: For proteins, disruption of the tertiary structure, causing the protein to lose its 3D conformation. For DNA, breaking of hydrogen bonds between complimentary base pairs causing the 2 DNA strands to separate.
  • When given an enzyme graph, take note of the Y axis. Is it a rate of reaction or concentration of product, even concentration of substrate and adjust answers accordingly.

BYang’s tough question bank

  • The release of human growth hormones are known to increase as body temperature increases. Once released, they bind to their cognate receptors in target cells which result in increased metabolic activities. Whilst some question if this is a result of temperature extremes, the human growth hormone effects were not observed at low temperatures. Suggest why it would be advantageous to couple increased temperatures to human growth hormone response. [3m. Created 210923]
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