The Chemical The Chemical Context Context of Life of Life Lec # 2 Instructor: Dr. Hatem Eideh Course: General Biology 0200102 Reference: Reece JB, Urry LA, Cain ML, Wasserman SA, Minorsky PV and Jackson RB (2011). Campell Biology, 9 th ed. Boston: Pearson Education. . Chap 2
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The Chemical Context of Life Lec # 2 Instructor: Dr. Hatem Eideh Course: General Biology 0200102 Reference: Reece JB, Urry LA, Cain ML, Wasserman SA, Minorsky.
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The Chemical The Chemical Context Context of Lifeof Life
Lec # 2
Instructor: Dr. Hatem EidehCourse: General Biology 0200102
Reference:Reece JB, Urry LA, Cain ML, Wasserman SA, Minorsky PV and Jackson RB (2011). Campell Biology, 9th ed. Boston: Pearson Education. . Chap 2
Introduction: Introduction: Who Tends This Who Tends This GardenGarden??
“Devil’s gardens”
Living organisms are composed of Living organisms are composed of about 25 chemical elementsabout 25 chemical elements
Living organisms are composed of matter, which is anything that occupies space and has mass (weight)
Matter is composed of chemical elements
Element—a substance that cannot be broken down to other substances by chemical reactions
There are 92 elements in nature—only a few exist in a pure state
Elements can combine to form Elements can combine to form compoundscompounds
Compound—a substance consisting of two or more different elements combined in a fixed ratio by mass (and by atoms)– There are many compounds that consist
of only two elements– Table salt (sodium chloride or NaCl) is
Atoms consist of protons, neutrons, and Atoms consist of protons, neutrons, and electronselectrons
An atom is the smallest unit of matter that still retains the properties of a element– Atoms are made of over a hundred
subatomic particles, but only three are important for biological compounds– Proton—has a single positive electrical charge– Electron—has a single negative electrical charge– Neutron—is electrically neutral
Unequal electron sharing creates polar Unequal electron sharing creates polar moleculesmolecules
In molecules of only one element, the pull toward each atom is equal, because each atom has the same electronegativity– The bonds formed are called nonpolar covalent bonds