G12 sl humanbiochem
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Transcript of G12 sl humanbiochem
Introduction
Energy Proteins Carbohydrates Lipids Micronutrients and Macronutrients Hormones Enzymes (AHL) Nucleic Acids (AHL) Respiration (AHL)
We derive our energy from the oxidation of food Fats (37 kJ g-1) Carbohydrates CO2 + H2O + energy Proteins (17 kJ g-1)
Males have a RDI of 10500 kJ, females 8000 kJ
Lipids have a greater ratio of H:O than carbohydrates (16:1 compared to 2:1)
Use calorimeter
Natural polymers made by amino acids.
Proteins important to humans are made of 20 α-amino acids (in data booklet)
Essential amino acids: amino acids our body cannot synthesize (10)
Complete protein: a protein made of essential amino acids, e.g. casein (milk, eggs, soybeans)
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H++ H2N-CHR-COO-← H
3N+-CHR-COO- → H
3N+-CHR-COOH + OH-
>At low pH>Extra H+ reacts with OH-
>[OH- ] drops>Equilibrium shifts to the right>H
3N+-CHR-COOH form
>positive charge
>At high pH>Extra OH- reacts with H+
>[H+] drops>Equilibrium shifts to the left>H
2N-CHR-COO- form
>negative charge
>At isoelectric point>identical ionizations>only zwitterion>H
3N+-CHR-COO- form
>no net charge
Jan 3, 2010 Human Biochemistry 15
H3N+-CHR-COO- + H+→ H
3N+-CHR-COOH +
H2O
>when H+ is added>equilibrium shifts to right
>[H+] drops>pH remains the same>buffer action
>when OH- is added>equilibrium shifts to left
>[OH-] drops>pH remains the same>buffer action
H2O + H
2N-CHR-COO-← OH- + H
3N+-CHR-COO-
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AminoLeft
AcidRight
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Primary structure>sequence of amino acids>characteristic of protein function
Secondary structure>folding of polypeptide chain>by Hydrogen bonds
α-helix: between atoms of the same chain, e.g. hair, wool
pleated sheet: between parallel chains, e.g. silk
random coil: no repeating pattern
Tertiary structure>3D shape of secondary structure> several types of interaction
Quaternary structure>3D shape of tertiary structures of different polypeptide chains
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Tertiary structureMyoglobin
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Quaternary structureHaemoglobin
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Structural (collagen, keratin) Catalysts (enzymes) Hormones (insulin) Antibodies (interferons) Transport (haemoglobin) Energy (from muscles)
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distance traveled by compounddistance traveled by solventR
f =
Rf is specific for each amino acid
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H++ H2N-CHR-COO-← H
3N+-CHR-COO- → H
3N+-CHR-COOH + OH-
>At isoelectric point (pH of buffer)>identical ionizations>only zwitterion>H
3N+-CHR-COO- form
>no net charge>not affected by electric field
Different amino acids have different isoelectric points
Jan 3, 2010 Human Biochemistry 28
Electrophoresis(constant pH)
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