Bio 1 Lecture 2

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BIOLOGY OF THE CELLCHEMICAL BASIS OF LIFEBiology 1 Lecture 2EPHRIME B. METILLO, PhD

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Multiverse = matter and energy. Energy is the capacity to do work. Matter hasmass and occupies space and composed of basic elements. Elements aresubstances consisting of one type of atom (C for diamond, gold or Au for gold.

Name Charge Location Mass

Proton +1 atomic nucleus 1.6726 X 10

-27

kgNeutron 0 atomic nucleus 1.6750 X 10-27 kg

Electron -1 electron orbital 9.1095 X 10-31 kg

Greek philosophers thought ancould not be broken down, butEnrico Fermi broke atoms intosubatomic particles:

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Atomic number = number of protons. Itis characteristic and unique for eachelement.

Atomic mass (or atomic weight) =number of protons and neutrons in.

Atoms of an element that have differingnumbers of neutrons (but a constant

atomic number) = isotopes.

Use of Isotopes: determine diet ofmummified or fossilized human asproportions of isotopes in tissues;biochemical pathways; age of fossils and

artifacts using radioactive isotopes,either directly on the fossil (if it is youngenough) or on the rocks that surroundthe fossil (for older fossils likedinosaurs); radiation used in medicaldiagnostic and treatment procedures.

Some are radioisotopes, whichspontaneously decay,releasing radioactivity. Othersare stable.

E.g. radioisotopes - Carbon-14(symbol 14C), and deuterium(Hydrogen-2; 2H). Stable

isotopes are12

C and1

H.

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Albert Einstein: E=mc2,electrons as particles andenergy quantum

Orbital = area of space, an electronwill be found 90% of the time. sorbital is spherical. Each orbital =maximum of 2 electrons, so atomicnumbers above 2 must fill the other

orbitals, like px, py, and pzorbitals(dumbbell shaped, along the x, y, andz axes respectively)

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Ionic bonds = formed between ions (atoms that gain or lose electrons). Chlorinewith only 7 seven electrons in their outer shells, gain acquiring a charge of -1.Sodium with one electron in outer shell, usually lose election = +1 charge.

Sharing of electrons form covalentbonds or electron-sharing bonds form.

Very fast moving electrons effectively fillor empty outer shells of atoms. Analogy- child custody: children are likeelectrons, spend some time with eitherparent. In a covalent bond, the electronclouds surrounding the atomic nuclei

overlap (see Figure).

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The sharing of a single electron pair is termed a single bond. When two pairsof electrons are shared, a double bond results, as in carbon dioxide. Triplebonds are known, wherein three pairs (six electrons total) are shared as in

acetylene gas or nitrogen gas.

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Polar covalent bond form whenelectrons spend so much time with >electronegativity or electron affinitycausing that end to have slightlynegative charge. Conversely, the loss of

the electrons from the other end leavesa slightly positive charge.

Hydrogen bonds is the weak electricalattraction between the positive end ofone molecule and the negative end ofanother. In a large enough quantity, H

bonds are strong enough to holdmolecules together or in a 3D shape.

slightly +slightly -

Molecules are compounds in which theelements are in definite, fixed ratios,

where atoms are held together usuallyby one of the three types of chemicalbonds. E.g., the sugar glucose has 6Carbons, 12 hydrogens, and 6 oxygensper repeating structural unit. Theformula is written C6H12O6.

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chemical reaction:

Reactants Products

A + B ABWATER:

Water has been referred to as theuniversal solvent of solutes:

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Water disassociates into H+ and OH- ions, where oxygen retains electronsand only one hydrogen = hydroxide. Pure water has the same number (orconcentration) of H+ as OH- ions.

Acidic solutions have more H+ ions than OH- ions. Basic solutions have the

opposite. An acid causes an increase in the numbers of H+ ions and a basecauses an increase in the numbers of OH- ions.

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Organic molecules are those that: 1) formed by the actions of living things;and/or 2) have a carbon backbone (E.g. Methane - CH4).

If we remove the H from one of the methane units below, and begin linking

them up, while removing other H units, we begin to form an organicmolecule.

When two methanes are combined, the resultant molecule is Ethane, whichhas a chemical formula C2H6.

Molecules made up of H and C are known as hydrocarbons.

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Polar molecules are attracted to water molecules and are hydrophilic. Nonpolarmolecules are repelled by water and do not dissolve in water; are hydrophobic.

Hydrocarbon is hydrophobic but if with ionized carboxyl (acid) (COOH), then moleculeis hydrophilic. Since cells are 70-90% water, if organic molecules have -OH (hydroxyl)

group which enable a molecule to be water soluble.

Isomers are molecules with identical molecular formulas but differ in arrangement oftheir atoms (e.g., glyceraldehyde and dihydroxyacetone).

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Classes of macromolecules (polysaccharides, triglycerides, polypeptides, nucleic acids)

1. Carbohydrates - formula [CH2O]n, n = 3-6. For short-term energy storage (suchas sugar); as intermediate-term energy storage (starch for plants and glycogen foranimals); and as structural components in cells (cellulose in the cell walls of plants and

many protists), and chitin in the exoskeleton of insects and other arthropods.Sugars are simplest carbohydrates, structural unit. Monosaccharides are single(mono=one) sugars: ribose (C5H10O5), glucose (C6H12O6), and fructose (glucoseisomer).

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Disaccharides = two monosaccharides bond together (sucrose = glucose+ fructose; lactose = glucose + galactose; maltose two glucose)

Polysaccharides are large molecules

composed of individualmonosaccharide units. A commonplant polysaccharide is starch:

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2. Lipids for long-term energy storage. Insoluble in polar water. Otherfunctions structural components (glycolipid; phospholipids in cellmembranes) and "messengers" (hormones) within and between cells.Lipids are composed of three fatty acids (usually) covalently bonded to a3-carbon glycerol. Fats and oils more complex storage form.

Phospholipid

Cholesterol

3 P i h l f i ( d i h ) E

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3. Proteins have control functions (enzymes and protein hormones). Enzymes arecatalysts that promotes but is not changed by a chemical reaction). Structural proteinsfunction in the cell membrane, muscle tissue, etc. Amino acids are building blocks ofproteins (amino, carboxylic acid, R group), 20 kinds.

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STRUCTURES:Primary (polypeptide)Secondary (coil or pleat due to H-bond R groups)

Tertiary (bonding and R repulsion)Quaternary (hemoglobin, more polypeptides)

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4. Nucleic acids are polymers composed of monomer units known asnucleotides. Nucleotides are information storage (DNA), protein synthesis(RNA), and energy transfers (ATP and NAD). Nucleotides = sugar, a nitrogenousbase, and a phosphate. Pentose sugars (ribose or deoxyribose). Nitrogenousbases are purines (Adenine and Guanine, double-ringed), and pyrimidines

(Cytosine, Thymine and Uracil, single-ringed)

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A mutation is any change in the DNA base sequence. Most mutations areharmful, few are neutral, and a very few are beneficial and contribute theorganism's reproductive success. Mutations are the wellspring ofvariation, variation is central to Darwin and Wallace's theory of evolutionby natural selection.

DNA only in nucleus (except chloroplasts and mitochondrion)RNA both nucleus and cytoplasm:Messenger RNA (mRNA) is the blueprint for construction of a protein.Ribosomal RNA (rRNA) is the construction site where the protein is made.Transfer RNA (tRNA) is the truck delivering the proper amino acid to the

site at the right time.

Put animation of protein synthesis:

http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter15/animations.html#