BIOL1007 Lecture Notes - Lecture 4: Alpha And Beta Carbon, Polymerization, Information Transfer
19 May 2018
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Department
Course
Professor
Identify the major features of proteins: peptide bond, amino and carboxyl terminals, side
chains, alpha carbon
Amino acid sequence determines structure which determines function
-
Give cell its shape
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Can form receptors, enzymes, hormones, growth factors, toxins, transporters, antibodies
-
Some hydrophobic
○
Some polar but uncharged (hydrophilic)
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Some positively charged at pH 7
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Some negatively charged at pH 7
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Composed of 20 different amino acids, with different side chains and subsequent properties -> diversity
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Proteins
Forms during translation
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Occurs on ribosomes
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Water excluded from active site
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Catalysed by RNA
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Amino acids must be activated by ATP first
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So eventually exists as
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Peptide bonds
-
L4 - info in biopolymers 2
Saturday, 12 August 2017
10:13 PM
Mod 1 Information transfer Page 1
Amino acids = zwitterions, as they have functional groups with opposite charges
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Alpha amino acid
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amino group - Positive at pH 7
▪
carboxyl group negatively charged at pH 7
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alpha carbon
▪
sidechain,
▪
Consists of
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Reaction is extremely thermodynamically unfavourable due to large amount of water around
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Hydrolysis always favoured over condensation in aqueous environment
▪
Amino acids combine, by condensation polymerisation to form a dipeptide
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Screen clipping taken: 12/08/2017 10:20 PM
Predict some chemical properties of amino acid side chains (solubility
hydrophobic/hydrophilic, polarity, charge) given their structure
Amino acid side chains
Hydrophobic
aliphatic
Chains
of -
CH2-
e.g. Leucine
Only C-C and C-H bonds in side
chain
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C and H have similar
electronegativities -> sharing of e-
fairly evenly -> little or no dipole
and no charges
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Mod 1 Information transfer Page 2
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Aromatic
Rings
with
double
bonds
e.g. Phenylalanine (hydrophobic)
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Tyrosine (polar, non-ionic, OH changes properties of side chain)
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Polar non-
ionic
Side
chains
with -
OH, -SH
or
e.g. Serine
Hydroxyl group is polar -> has
dipole
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Mod 1 Information transfer Page 3
Document Summary
Identify the major features of proteins: peptide bond, amino and carboxyl terminals, side chains, alpha carbon. Amino acid sequence determines structure which determines function. Can form receptors, enzymes, hormones, growth factors, toxins, transporters, antibodies. Composed of 20 different amino acids, with different side chains and subsequent properties -> diversity. Amino acids must be activated by atp first. Amino acids = zwitterions, as they have functional groups with opposite charges. Consists of amino group - positive at ph 7 carboxyl group negatively charged at ph 7 alpha carbon sidechain, Amino acids combine, by condensation polymerisation to form a dipeptide. Reaction is extremely thermodynamically unfavourable due to large amount of water around. Hydrolysis always favoured over condensation in aqueous environment. Predict some chemical properties of amino acid side chains (solubility hydrophobic/hydrophilic, polarity, charge) given their structure. Only c-c and c-h bonds in side chain.
