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Chapter 2 BIOLOGY AND SOCIETY M ore Precious than Gold A drought is Essential Chemistry for Biology - a period of abnormally dry weather that changes...

Please help me to do a reflection paper on Chapter 2-3.
1 Chapter 2 Chapter 2 Essential Chemistry for Biology • A drought is – a period of abnormally dry weather that changes the environment and – one of the most devastating disasters. BIOLOGY AND SOCIETY More Precious than Gold Figure 2.0 • Droughts can cause: – severe crop damage; shortages of drinking water – dust storms, famine, habitat loss, and mass migration. • Throughout human history, droughts have helped wipe out societies and even whole civilizations. • Droughts are catastrophic because life cannot exist without water. BIOLOGY AND SOCIETY More Precious than Gold SOME BASIC CHEMISTRY • Why chemistry? I thought this was a biology course • Well, take any biological system apart, and you eventually end up at the chemical level. – Indeed, your body is one big container of chemicals undergoing a continuous series of chemical reactions Matter: Elements and Compounds Matter is anything that occupies space and has mass. • Matter is found on the Earth in three physical states: – Solid – Liquid – Gas • Matter is composed of chemical elements. An element is a substance that cannot be broken down into other substances by chemical reactions • There are 92 naturally occurring elements on Earth. – Each element has its own symbol – All of the elements are listed in the periodic table.
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2 H Rb K Na Li Fr Cs Sr Ca Mg Be Ra Ba Y Sc Ac La Zr Ti Rf Hf Nb V Db Ta Mo Cr Sg W Tc Mn Bh Re Ru Fe Hs Os Rh Co Mt Ir Pd Ni Uun Pt Xe Kr Uuo Rn Ag Cu Uuu Au Cd Zn Uub Hg Ar Ne In Ga Tl Al B Sn Ge Uuq Pb Si C Sb As Bi P N Te Se Uuh Po S O I Br At Cl F He Th Ce Pa Pr U Nd Np Pm Pu Sm Am Eu Lr Lu Cm Gd Bk Tb Cf Dy Es Ho Fm Er Md Tm No Yb 6 C 12 Figure 2.1 Atomic number (number of protons) Mass number (number of protons plus neutrons) Element symbol Mercury ( Hg ) Figure 2.1 Copper ( Cu ) Lead ( Pb ) • Twenty-five elements are essential to people – Other organisms need fewer • Four elements make up about 96% of the weight of most cells: – Oxygen (O) – Carbon (C) – Hydrogen (H) – Nitrogen (N) Carbon ( C ) : 18.5% Hydrogen ( H ) : 9.5% Nitrogen ( N ) : 3.3% Calcium ( Ca ) : 1.5% Trace elements: less than 0.01% Boron ( B ) Manganese ( Mn ) Oxygen ( O ) : 65.0% Magnesium ( Mg ) : 0.1% Phosphorus ( P ) : 1.0% Potassium ( K ) : 0.4% Sulfur ( S ) : 0.3% Sodium ( Na ) : 0.2% Chlorine ( Cl ) : 0.2% Cobalt ( Co ) Chromium ( Cr ) Iron ( Fe ) Iodine ( I ) Fluorine ( F ) Copper ( Cu ) Silicon ( Si ) Zinc ( Zn ) Vanadium ( V ) Tin ( Sn ) Molybdenum ( Mo ) Selenium ( Se ) Figure 2.2 Trace elements – Occur in very small amounts – However, they are essential for life – There are 14 of these elements – Examples: – Iodine (I) – Fluorine (F) – Iron (Fe) • Iodine is an essential ingredient of a hormone produced by the thyroid gland (in the neck) – Iodine deficiency causes goiter. Figure 2.3 • Fluorine is added to dental products and drinking water – It helps to maintain healthy bones and teeth.
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1 Chapter 3 Chapter 3 The Molecules of Life BIOLOGY AND SOCIETY Got Lactose? • Lactose is the main sugar found in milk. • Some adults exhibit lactose intolerance, the inability to properly digest lactose. • Lactose-intolerant individuals are unable to digest lactose properly. – Lactose is broken down by bacteria in the large intestine producing gas and discomfort. • There is no treatment for the underlying cause of lactose intolerance. • Affected people must – Avoid lactose-containing foods or – Take the enzyme lactase in pill form when eating foods with dairy products Figure 3.0 ORGANIC COMPOUNDS • A cell is mostly water. • The rest of the cell consists mainly of carbon- based molecules. • Carbon forms large, complex, and diverse molecules necessary for life’s functions. Organic compounds are carbon-based molecules. Carbon Chemistry • Carbon is a versatile atom. – It has four electrons in an outer shell that holds eight electrons. – Carbon can share its electrons with other atoms to form up to four covalent bonds. • Carbon can use its bonds to – Attach to other carbons – Form an endless diversity of carbon skeletons Carbon skeletons vary in length Carbon skeletons may have double bonds, which can vary in location Carbon skeletons may be unbranched or branched Carbon skeletons may be arranged in rings Double bond Figure 3.1 Animation : Carbon Skeletons Note : All animations referred to in this handout are found in the Chapter 3 Folder on Blackboard
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2 • The simplest organic compounds are hydrocarbons, which are organic molecules containing only carbon and hydrogen atoms. • The simplest hydrocarbon is methane, consisting of a single C atom bonded to four H atoms. Structural formula Ball-and-stick model Space-filling model Figure 3.2 • Larger hydrocarbons form fuels for engines. • Hydrocarbons of fat molecules fuel our bodies. Figure 3.3 Dietary fat Octane • Each type of organic molecule has a unique three-dimensional shape. • The shapes of organic molecules relate to their functions. – Many vital processes within living organisms rely on the ability of molecules to recognize one another based on their shape • The unique properties of an organic compound depend on – Its carbon skeleton – The atoms attached to the skeleton • The groups of atoms that usually participate in chemical reactions are called functional groups . Two common examples are – Hydroxyl groups (–OH) – Carboxyl groups (C=O) • Many molecules have two or more functional groups Giant Molecules from Smaller Building Blocks • On a molecular scale, many of life’s molecules are gigantic, earning the name macromolecules . • Three categories of macromolecules are – Carbohydrates – Proteins – Nucleic acids • Most macromolecules are polymers. Polymers are made by stringing together many smaller molecules called monomers . • A dehydration reaction – Links two monomers together – Removes a molecule of water Animation : Polymers
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