Chapter 4 

enzyme

Metabolism: all chemical reaction occurs in the body
Catabolism: breaking-down process, eg. deamination
anabolism: building-up process, eg. photosynthesis

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characteristics of enzymes (cartoon)

-they are protein 

-a catalyst to speed up reaction inside the cell (lower the activation energy of a reaction)

-specific (acts on a few types of substrate only)

-denature under high temperature

-inactive under low temperature and extreme ph

-reusable


use of enzyme :
enzyme + substrate -> enzyme substrate complex -> product + enzyme

Diffusion (no energy required):
movement of the molecules from the higher concentration region to the lower concentration region

Osmosis (no energy required):
movement of water from the higher concentration region to the lower concentration region through a selectively permeable membrane

active transport (require energy from respiration):
movement of particles against a concentration gradient.




hypotonic solution=solution with high water potential
hypertonic solution=solution with low water potential
when 2 solution have the same solute concentration (water potential) ,the are then be called isotonic

osmosis in animal cells:
shrink (in hypertonic solution)
burst (in hypotonic solution)
osmosis in plant cells:
shrink (in hypertonic solution)
plasmolasyed (in hypotonic solution)

MC Questions