Biology Chapter 4 - Carbon and the Molecular Diversity of Life.docx

This cross linking helps stabilize protein structure

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Two sulfhydryl groups can react, forming a covalent bond. This “cross-linking” helps stabilize protein structure. Cross-linking of cysteines in hair proteins maintains the curliness or straightness of hair. Straight hair can be “permanently” curled by shaping it around curlers and then breaking and re-forming the cross-linking bonds. Disulfide cross-linking helps hold a long amino acid sequence in a particular shape 6. Phosphate Contributes negative charge to the molecule of which it is a part (2– when at the end of a molecule, as at left; 1– when located internally in a chain of phosphates). Molecules containing phosphate groups have the potential to react with water, releasing energy. 7. Methyl Methylated compounds Addition of a methyl group to DNA, or to molecules bond to DNA, affects the expression of genes. Arrangement of methyl groups in male and female sex hormones affects their shape and function. ATP: An Important Source of Energy for Cellular Processes An important organic phosphate is adenosine triphosphate ( ATP )
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ATP consists of an organic molecule called adenosine attached to a string of three phosphate groups ATP stores the potential to react with water, a reaction that releases energy to be used by the cell The Chemical Elements of Life: A Review The versatility of carbon makes possible the great diversity of organic molecules Variation at the molecular level lies at the foundation of all biological diversity H O N C 1 2 3 4 Hydrogen needs 1 electron to complete its valence shell. Oxygen needs 2. Nitrogen needs 3. Carbon needs 4.
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