BIS104 Slide1 - Cell Lecture 1 Evolution and Cells &...

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Lecture 1 Evolution and Cells & Overview of cell machinery Cell Amino acids sugars fatty acids nucleotides ! the vehicle for transmitting genetic materials to the next generation ! the minimal self-reproducing unit Cell ! Development of this self-replicating system allows evolution and natural selection to operate A brief history of life on earth 4.5 billion years ago 3.5 billion years ago 1.5 billion years ago 0.5 billion years ago Earth formed First life- prokaryotic bacteria dominate Nucleated cells arise- eukaryotic Multicellular eukaryotes arise RNA Store genetic information Functions as catalysts (ex. ribozymes) phenotype genotype ( genome, hereditary material ) (physical appearance ) More efficient systems evolved Proteins DNA dsDNA (genotype) RNA Proteins (catalysis) Structures & phenotypes more stable more versatile catalysts vs RNA Development of translation was a major step in evolution of phenotype Exceptions: some viruses (influenza, HIV genome) and Translation (ribosomes) are still RNA based
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: weak Nucleophil, attacks phosphodiester bond between two ribonucleotides (RNA hydrolyzes itself slowly) Why is RNA less stable? 2’-OH : weak Nucleophil, attacks phosphodiester bond between two ribonucleotides (RNA hydrolyzes itself slowly) Why is RNA less stable? 2’-OH becomes stronger nucleophil in alkali ( alkaline hydrolysis ) Organic soup How does first cell arise ? First cell is defined by creation of cell membrane DNA DNA DNA Present day cells RNA RNA RNA RNA RNA Bactrium Mycoplasma genitalium (a genus of bacteria that lacks cell wall) Has the smallest genome (~500 genes) Figure 1-14a Molecular Biology of the Cel
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BIS104 Slide1 - Cell Lecture 1 Evolution and Cells &...

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