lecture_10 - M a j o r D o m a i n s o f L i f e Based on...

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Unformatted text preview: M a j o r D o m a i n s o f L i f e Based on rRNA data, proposed by C. Woese Eric Gaba, NASA Lattimer, AST 248, Lecture 10 – p.1/13 T y p e s o f C e l l s Prokaryotes Cells without nuclei Eukaryotes Cells with nuclei Viruses Major Differences: • Prokaryotes form domains of bacteria or eubacteria and archaea. • Prokaryotes form single-celled organisms, but can cluster into colonies. • Prokaryotes are enclosed by a cell wall made of cross-linked chains of peptidoglycan (amino acids + sugar) which maintains size and shape of cell. • Metabolism in prokaryotes is complex and more diverse. • Prokaryotic genome is smaller, and its DNA is not attached to histone proteins. • Most prokaryotic DNA is present in a single circular chromosome, and replication begins at a single point and proceeds around the circle in both directions. • Prokaryotes obtain new genes by conjugation (transferral), transformation (absorbed from environment) and transduction (transferral by viruses or phages. • Ribosomes of eubacteria differ in molecular detail from those of eukaryotes and archaea. Mariana Ruiz Lattimer, AST 248, Lecture 10 – p.2/13 M e t a b o l i s m • Chemical processses that provide energy and nutrients to cells. Without cell’s presence, these reactions would occur too slowly to be useful. Cell’s primary purpose is to speed up these reactions. • Metabolism requires both sources of raw materials and energy to break down old molecules and manufacture new ones. • Cells have the ability to produce a large variety of products from a very limited set of starting materials, utilizing a diverse array of enzymes. • Regardless of where energy comes from, cells utilize the same molecule (ATP, adenosine triphosphate) to store and release energy....
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This note was uploaded on 07/16/2008 for the course BI 120 taught by Professor Wilson during the Summer '08 term at Mass Colleges.

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lecture_10 - M a j o r D o m a i n s o f L i f e Based on...

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