01:119:115 Lecture Notes - Lecture 3: Chitin, Dehydration Reaction, Glycerol
3 Oct 2018
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Bio Notes Week 2 9/11/18
Biological Importance of Carbon
→ CC Functional Groups
❖ Carbon-
o Organic compounds- C bonded with C or H
o The study of carbon compounds → the chemistry of life
o Cells 70-90% H2O, most of the rest is carbon-based compounds
o Backbone- Can vary in 4 ways. (a) length, (b)Double bond position (c)branching
(d)presence of rings. Geometry affects function.
o Valence e- dictate bonding properties, Hydrogen: 1 v e-, Oxygen: 2 v e-, Nitrogen,
3 ve-, carbon: 4 v e-. Carbon is at the center of things because it is physically able
to be a part of complex molecules
❖ Hydrocarbons- Organic molecules of only C and H. (Exp. Methane CH4). Non-polar,
uncharged (nonionic), hydrophobic
o Can contain functional groups. Replace one or more H.
❖ Functional Groups→ key to molecular function
o Replace H with something else and changes biological properties of the
molecule. (Exp. Estradiol vs. testosterone)
o Slight differences in functional groups causes completely different biological
properties. Small changes can have huge consequences
o Insert: Fig 4.9
▪ Hydroxyl Group (-OH). Oxygen bound to Hydrogen. Molecules: alcohols,
ethanols, (ends in -ol). Polar and Hydrophilic
• Very strongly polar.
▪ Carbonyl Group (=O). Carbon double covalent bond to O. Polar and
hydrophilic- but not all polar molecules are equal
• Slightly polar. Electronegativity’s are closer to only moderately
asymmetrical.
• Can be in middle of molecule or on the end.
▪ Carboxyl Group (-COOH). Carbon double bonded to O and a single bond
to Oh. Can release proton (H+) → acidic (carboxylic acids). Polar
hydrophilic, important part of amino acids.
• Acid part of amino acids
▪ Amino Group (-NH2). N bound to 2 H’s. Proton H+ acceptor → basic.
Important component of amino acids
• Hydrophilic because charged rather than neutral.
2
▪ Sulfhydryl Group (-SH). Sulfer bound to H. Often important in protein
structure
• Also polar, but weakly polar. S is different enough from H that it is
slightly polar, but they are pretty similar so it’s weakly polar.
▪ Phosphate Group (-PO2H2). O bonded to phosphorous (Po), bonded to 1
O, 2 OHs. 1 double bond present. Can release 1 or both H+ - exists ionized
and non-ionized. Acidic, hydrophilic, found in phospholipids and nucleic
acids.
▪ Methyl Group (-CH3). Carbon bonded to H, all single bonds. Hydrophobic,
non-polar. In DNA, effects gene expression.
• ONLY non-polar ones. Everything else is charged.
• Epigenetic regulation- Methyl group
❖ Summarize functional groups
o Chem groups that replace H in hydrocarbons. Affect chemical properties
of molecules. Often dictates function. Memorize figure 4.9
Biological Macromolecules
→SEQ Process of Polymerization
→ CC Classes of Biological Molecules
❖ Macromolecules
o Large molecules- thousands of atoms
o Polymers: produced by monomers
▪ Monomers: identical or structurally similar
o Dehydration Reaction (Synthesis): synthesizing a polymer. Dehydration removes
a water molecule, forming a new bond.
▪ Enzyme: dehydrogenase (remove hydrogens) which results in a new
bond
o Hydrolysis: breaking down a polymer. Hydrolysis adds a water molecule,
breaking a bond. (lysis- to splits a water and adds it to each of the molecules and
now formed a new molecule).
▪ Enzyme: hydrolases
o 4 Classes of Biological Molecules
▪ Carbohydrates- made of C, H, O
• Approximate ratio of CH2O 1:2:1
• Monosaccharides: Monomers are sugars- 3-7 C, hydroxyl groups,
carbonyl groups. So SUPER hydrophilic.
o Exp) sugar in tea and then dissolves really quick
o Fuel and structure. Tend to end with “-ose” (glucose)
o Single sugar→ monosaccharide: classified by location of
carbonyl group
Document Summary
Geometry affects function: valence e- dictate bonding properties, hydrogen: 1 v e-, oxygen: 2 v e-, nitrogen, Carbon is at the center of things because it is physically able to be a part of complex molecules. Hydrocarbons- organic molecules of only c and h. (exp. Non-polar, uncharged (nonionic), hydrophobic: can contain functional groups. Functional groups key to molecular function: replace h with something else and changes biological properties of the molecule. (exp. Estradiol vs. testosterone: slight differences in functional groups causes completely different biological properties. Polar and hydrophilic: very strongly polar, carbonyl group (=o). Carbon double covalent bond to o. polar and hydrophilic- but not all polar molecules are equal: slightly polar. Ele(cid:272)t(cid:396)o(cid:374)egati(cid:448)ity"s are closer to only moderately asymmetrical: can be in middle of molecule or on the end, carboxyl group (-cooh). Carbon double bonded to o and a single bond to oh. Can release proton (h+) acidic (carboxylic acids).
