Georgia Tech School of Biology Georgia TechBiol 1510 Molecules of life: what are we made of, and how did we get that way? Atomic elements Organic molecules.

Georgia Tech School of Biology

Georgia TechBiol 1510

Molecules of life: what are we made of, and how did we get that way?

• Atomic elements• Organic molecules• Electronegativity• Chemical bonds

All images are from Wikimedia Commons, unless otherwise noted.



elemental abundance: human body ocean water Earth crust

Element Proportion (by mass)

Oxygen 65% 86% 46%

Carbon 18% 0.0028% 0.18%

Hydrogen 10% 11% 0.15%

Nitrogen 3% 0.0016% 0.002%

Calcium 1.5% 0.04% 5%

Phosphorus 1.2% 0.000006% 0.1%

Potassium 0.2% 0.04% 1.5%

Sulfur 0.2% 0.091% 0.42%

Chlorine 0.2% 1.94% 0.017%

Sodium 0.1% 1.08% 2.3%

Magnesium 0.05% 0.13% 2.9%

Iron < 0.05% 6.3%

Cobalt < 0.05%

Copper < 0.05%

Zinc < 0.05%

Iodine < 0.05%

Selenium < 0.01%

Fluorine < 0.01%

What are we made of?



Atomic structure and valence electrons



Periodic table of the elements – rows 1-5



What determines what kind of bond forms between atoms?

Element Electro-negativity

O 3.44

Cl 3.16

N 3.04

S 2.58

C 2.55

H 2.20

Na 0.93

Pauling scale, Wikipedia



How do molecules behave in water?



Which of these are organic molecules?

A. methane B. carbon dioxide

C. carbonic acid D. formic acid



What is the difference, then, between organic carbon and inorganic carbon?

“The purpose of life is to hydrogenate carbon dioxide” – Sean Carroll

“The purpose of life is to hydrogenate carbon dioxide” – Sean Carroll



Molecules of Life

Four major kinds of molecules make up the bulk of a cell

• Carbohydrates• Nucleic acids• Lipids• Proteins



Sources: Watson JD: Molecular Biology of the Gene, 2nd ed., Philadelphia, PA: Saunders, 1972Freitas RA Nanomedicine, 1998, http://www.foresight.org/Nanomedicine/Ch03_1.htmlUshiyama K: Plant Cell Culture in Japan, p. 97 (1991). Eds. Komamine, A., CMC Co. Ltd., Tokyo, Japan



Macromolecules (very large molecules)

3 questions

http://bio1510.biology.gatech.edu/module-3-molecules-membranes-and-metabolism/biological-molecules-2/



Carbohydrates, glycans, polysaccharides

disaccharide

glucose



Nucleic acids (DNA and RNA)



Phosphodiester bonds T



Nucleic acids have secondary structure



Glycans (polysaccharides)

Nucleic acids (DNA and RNA)

Proteins(polypeptides)

Subunits monosaccharides

Elemental Composition

C, H, O, N, S

Bonds between subunits

Phosphodiester

Structure

Cellular functions



Molecules of Life

Protein structure• Amino acids• Peptide bonds• Levels of protein structure• Hemoglobin example



Proteins (polypeptides) are linear chains of amino acids linked by peptide bonds



Nonpolar amino acids - hydrophobic



Polar amino acids - hydrophilic

Dan Cojocari, Dept Medical Biophysics, U. Toronto 2011 Wikimedia Commons



Protein structure



Secondary structure: alpha-helix



Secondary structure: beta-sheet



What holds the tertiary structure together?

Campbell Biology, 8th ed.



Protein structure and function example – sickle cell hemoglobin

http://gingi.uchicago.edu/hbs2.html



Hemoglobin S differs from Hemoglobin A at what levels of protein structure?

http://www.carnegieinstitution.org/first_light_case/horn/lessons/sickle.html



Wikipedia

Valine 6 causes additional interactions

http://www.carnegieinstitution.org/first_light_case/horn/lessons/sickle.html

Georgia Tech School of Biology Georgia TechBiol 1510 Molecules of life: what are we made of, and how did we get that way? Atomic elements Organic molecules.

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