Transcript LE-Ch-2-Biochemistry

The Chemistry of Life
What are living
creatures made of?
Why do we have
to eat?
Regents Biology
2006-2007
Elements of Life
 96% of living
organisms is
made of:




carbon (C)
oxygen (O)
hydrogen (H)
nitrogen (N)
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The World of Elements
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Ionization of water & pH
Water ionizes
-H+ splits off from H2O, leaving OH–
-if [H+] = [-OH], neutral = 7
-if [H+] > [-OH], acidic = 0-6.9
-if [H+] < [-OH], basic = 8-14
pH scale

how acidic or basic a solution is

0  7  14
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H2O  H+ + OH–
H+ Ion
Concentration
pH Scale
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pH
Examples of Solutions
100
0
10–1
1
10–2
2
Stomach acid, Lemon juice
10–3
3
Vinegar, cola, beer
10–4
4
Tomatoes
10–5
5
Black coffee, Rainwater
10–6
6
Urine, Saliva
10–7
7
Pure water, Blood
10–8
8
Seawater
10–9
9
Baking soda
10–10
10
Great Salt Lake
10–11
11
Household ammonia
10–12
12
Household bleach
10–13
13
Oven cleaner
10–14
14
Sodium hydroxide
Hydrochloric acid
pH & cellular regulation
pH of cells must be kept ~7
-pH affects shape of molecules
-shape of molecules affect function
-pH affects cellular function
Buffering
range
pH
9
8
7
6
5
4
3
2
1
0
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0
1
2
3
4
5
Amount of base added
Molecules of Life
 Put C, H, O, N together in different
ways to build living organisms
 What are bodies made of?

carbohydrates
 sugars & starches
proteins
 fats (lipids)
 nucleic acids

 DNA, RNA
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Why do we eat?
 We eat to take in more of these chemicals

Food for building materials
 to make more of us (cells)
 for growth
 for repair

Food to make energy
 calories
 to make ATP
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ATP
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What do we need to eat?
 Foods to give you more building blocks
& more energy
 for building & running bodies
carbohydrates
 proteins
 fats
 nucleic acids
 vitamins
 minerals, salts
 water

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Don’t forget water
 Water
65% of your body is H2O
 water is inorganic

 doesn’t contain carbon
 Rest of you is made of carbon molecules

organic molecules
 carbohydrates
 proteins
 fats
 nucleic acids
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How do we make these molecules?
We build them!
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2006-2007
Building large molecules of life
 Chain together smaller molecules

building block molecules
 Big molecules built from little molecules

polymers
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Building large organic molecules
 Small molecules = building block
(monomers-glucose)
 Bond them together = polymers

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(starch)
Building important polymers
Carbohydrates = built from sugars
sugar – sugar – sugar – sugar – sugar – sugar
Proteins = built from amino acids
amino amino amino amino amino amino
acid – acid – acid – acid – acid – acid
Nucleic acids (DNA) = built from nucleotides
nucleotide – nucleotide – nucleotide – nucleotide
(Nucleotide=sugar,phosphate,base)
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How to build large molecules
 Synthesis
building bigger
molecules from smaller
molecules
 building cells & bodies

+
ATP
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How to take large molecules apart
 Digestion (hydolysis)
taking big molecules apart
 getting raw materials
 making energy (ATP)

Disaccharide=2 sugars
2 monosaccharides
+
ATP
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Example of digestion
ATP
ATP
ATP
ATP
ATP
starch
ATP
glucose
ATP
 Starch is digested to glucose
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Example of synthesis
amino acids
protein
 Proteins are synthesized by bonding amino acids
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