WhatsInACell-notes

WhatsInACell-notes - Whats in a cell W hat are cells?...

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© M. S. Shell 2009 1/12 last modified 9/29/2010 What’s in a cell What are cells? Basic, most fundamental unit of life Diversity and characteristics size: micrometers (bacterial) to millimeter (egg cells) shape: spherical (bacteria), highly extended (human nerve), hairy (paramecium), tailed (bacteria) What’s in common: DNA – genetic information, recipes o genome is the information o evolution acts upon the information through mutations of DNA to create new species and species diversity RNA – copies of recipes sent to protein factories proteins – the “worker” molecules that accomplish many biomolecular functions Basic categories of cells: prokaryotes – no nucleus o bacteria – most familiar o archea – hostile environments (acidic, high temperature) eukaryotes – has nucleus, typically bigger in size o plants, animals, fungi How is a cell similar to or different from chemical processing? Similar: unit operations = specialized molecules, processes, compartments, organelles that are reused again and again
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© M. S. Shell 2009 2/12 last modified 9/29/2010 master control = DNA energy optimization many steps often required to accomplish simple cell behavior limited by same laws of physics: thermodynamics, kinetics, transport Different: much smaller; interfacial interactions can play very important roles very robust redundancies and error-correction for chemical processes highly heterogeneous, crowded mixtures most processes happen in much smaller molecular copy numbers b need to consider molecular behavior that is often different from bulk b random fluctuations can be significant [ex: concentration profile] Interactions All cellular molecular building blocks are governed by the same kinds of interactions and physiochemical processes that dictate the properties of nonliving things in nature and in synthetic chemicals and materials. A critical challenge is identifying how these interactions result in much more complex behavior in living systems than in synthetic ones. At a fundamental level, all interactions are described by electrostatics due to electron clouds interacting with nuclei. A quantum description is ultimately required, but we can find simple common ways that the quantum behavior manifests. Here we will take a simple picture in understanding what interactions between two atoms entail. It will be important to consider their pairwise separation distance g : at large separation distances – energy should be zero (normalization condition) attractive – negative, decreasing interaction energy when atoms come close repulsive – positive, increasing interaction energy when atoms come close
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© M. S. Shell 2009 3/12 last modified 9/29/2010 Covalent bonds One of the strongest chemical interactions between atoms. Involves sharing electrons and emerges from the quantum mechanical solution. Magnitude is typically 100 kcal/mol
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WhatsInACell-notes - Whats in a cell W hat are cells?...

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