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MORE BIOCHEM: PLO B2 and B4
Name: _______________
Water
-
Covalent bonds between the atoms
a polar molecule – charged unevenly
2 water molecules will form a loose bond – hydrogen
bond (weak bond)
http://www.northland.cc.mn.us/biology/Biology1111/animations/hydrogenbonds.html
Demo: How does water respond to a static charge?
Properties of water
1.
universal solvent
- other charged particles can dissolve in it
- e.g. salt (NaCl) can dissolve in water.
http://programs.northlandcollege.edu/biology/Biology1111/animations/dissolve.html
Hydrophilic (love water) – some ions and molecules interact well with water. E.g. salts, sugars, acids,
alkalis, polysaccharides, DNA, proteins and some gases – especially oxygen, carbon dioxide
Hydrophobic (hate/fear water) – some ions and molecules do not interact with water. E.g. oil, fat which
are lipids
Demo: Let’s try to dissolve salt and oil in water.
2.
Lubricant
- Water molecules cling together due to the hydrogen bonding but they flow freely
- Our blood is 92% water
- Helps our joints to move easily
3.
Temperature regulator
- Hydrogen bonds absorb heat slowly and then hold it for a long time
- This is why there are no major fluctuations in our body temperatures
- Also sweat uses body heat to evaporate it and this cools the body down
Reactions that Involve Biological Molecules and WATER
Monomers: small molecules that can be chemically bonded to form polymers e.g. glucose, fatty acids,
nucleotides and amino acids
Polymers: large molecules made up of a linked series of repeated simple monomers e.g.
polysaccharides such as glycogen, starch and cellulose and also DNA, proteins and fats.
1.
Dehydration Synthesis
Monomers join and water is removed
Monomer
+
monomer
polymer
+
water
e.g.
glycerol
+
3 fatty acids
triglyceride (fat)
+
water
2.
Hydrolysis
Water is used to break the bond between monomers
e.g.
Polymer
+
water
monomer
+
monomer
sucrose
+
water
glucose
+
fructose
http://nhscience.lonestar.edu/biol/dehydrat/dehydrat.html
Video on dehydration synthesis and hydrolysis
QUESTION: What comparison can be made between dehydration synthesis and hydrolysis?
dehydration synthesis and hydrolysis are opposites of each other