bio review for dat

8/3/2019 Bio Review for Dat

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BIO REVIEW FOR DAT

CHEMISTRY

ATOMS, MOLECULES, IONS, AND BONDS

Atom: consists of a nucleus of positively charged protons and neutrally charged neutrons surrounded by

an electron cloud

Molecules: groups of two or more atoms held together by chemical bonds

Electronegativity: the ability of an atom to attract electrons

3 Kinds of Bonds:

1. Ionic: bonds between metal and nonmetal. One or more electrons transferred Ex: NaCl

2. Covalent Bonds: electrons shared electronegativities are similar a. Nonpolar covalent: electrons shared equally

y Ex: O2

b. Polar covalent: electrons shared unequally

y Ex: H20

3. Hydrogen Bonds: weak bonds between molecules, positively charged H+ in a covalently bonded

molecule become attracted to a negatively charged atom in another covalently bonded

molecule

PROPERTIES OF WATER

1. Water is an excellent solvent

2. Water has a high heat capacity

a. Heat Capacity: is the degree to which a substance changes temperature in response to

gain or loss of heat

3. Ice floats

4. Water has strong cohesion and high surface tension

a. Cohesion: the attraction between like substances (high level of H+ bonding in water)

5. Water has strong adhesion

a. Ad hesion: the attraction of unlike substances

y Ex: capillary action in a tube or through paper

ORGANIC MOLECULES

Macromolecules: large organic molecules that may consist of hundreds or thousands of atoms (most

macromolecules are polymers)

Polymers: molecules that consist of a single unit monomer repeated many times



Functional Groups: gives molecule a particular property such as acidity or polarity

Functional Groups Class Name Examples Characteristics

OH / Hydroxyl Alcohol Ethanol, Glycerol, Sugars Polar, Hydrophilic

COOH / Carboxyl Carboxylic Acids Acetic Acid, Amino Acids,

Fatty Acids, Sugars

Polar, Hydrophilic, Weak

Acid

NH2 / Amino Amines Amino Acids Polar, Hydrophilic,Weak

Base

PO3 / Phosphate Organic Phosphates DNA, ATP, Phospholipids Polar, Hydrophilic, Acid

C=O / Carbonyl Ketones Acetone, Sugars Polar, Hydrophilic

HCO / Carbonyl Aldehydes Formaldehyde, Sugars Polar, Hydrophilic

CH3 / Methyl Fatty Acids, Oils, Waxes Nonpolar, Hydrophobic

FOUR CL ASSES OF ORG ANIC MOLE C ULES

CARBOHYDRATES

Sugar molecules have the for mula (C H2O) n, hence the name Carbo Hy d rate n being any number

from 3 8

Monosaccharide: a single sugar molecule

1. Glucose: n = 6 C6H12O6

a. alpha and beta glucose differ by the reversal of H and OH on the first carbon



Disaccharide: two sugar molecules joined by a glycosidic linkage

1. Glycosidic Linkage: formed due to H2O loss

2. Condensation Reaction: a simple molecule is lost

a. Ex : dehydration loss of H2O

3. Glucose + Fructose = Sucrose 4. Glucose + Galactose = Lactose

5. Glucose + Glucose = Maltose

Polysaccharide: a polymer of monosaccharides that can contain thousands of monomers in a chain

1. Starch: polymer of E-glucose molecules that is the principal ener gy storage molecule in plant

cells

2. Glycogen: polymer of E-glucose molecules that differ in branching structure in comparison to

starch making them the major ener gy storage molecule in animal cells3. Cellulose: a polymer of F-glucose molecules that is the str uct ural molecule in the walls of

plant cells

4. Chitin: similar to cellulose except that each F-glucose molecule has a nitrogen containing group

attached. A structural molecule in the walls of fungus cells and exoskeletons of insects, other

arthropods and mollusks.

LIPIDS

Lipi d s are a class of substances that are insol uble in polar solvents but are sol uble in nonpolar substances

such as ether or chlorofor m. There are 3 major grou ps of lipi d s

1. Triglycerides (Triglycerols): fats and oils that consist of three fatty acids attached to a glycerol

molecule

a. F atty Aci d s: are hydrocarbons with a carboxyl group (COOH) at one end of the chain

y Saturated Fatty Acid: All carbons have a single covalent bond to either a carbon

or hydrogen except for the single carboxyl group

o Ex: the carbons are sat urated with hydrogens

y Monounsaturated Fatty Acid: has only one d ouble covalent bond

y Polyunsaturated Fatty Acid: has two or more d ouble covalent bonds



2. Phospholipids: just like a triglyceride except that one of the fatty acid chains are replaced by a

phosphate group

a. Am phipathic: has both polar and nonpolar regions

y the phosphate head is polar... hy d rophilic

y the two fatty acid tails are nonpolar hy d rophobic

y found in cell membranes

3. Steroids: Are characterized by a backbone of four linked carbon rings

a. Ex : cholesterol, testosterone, estrogen



PROTEINS

Proteins can be grou ped accor d ing to their f unctions

1. Structural Proteins:

a. keratin in hair and horns

b. collagen in connective tissue

c. silk in spider webs

2. Storage Proteins:

a. casein in milk

b. ovalbumin in egg whites

3. Transport Proteins:

a. membrane proteins

b. hemoglobin

4. Defensive Proteins:

a. Antibodies

5. Enzymes: regulate the rate of chemical reactions

All proteins are poly mers of amino aci d s



F our levels d escribe the str uct ure of a protein

1. Primary Structure: describes the order of amino acids

a. Ex : Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Arg-Gly

2. Secondary Structure: 3D shape that results from hydrogen bonding between the amino and

carboxyl groups of adjacent amino acidsa. alpha helix

b. beta pleated sheet

c. proteins whos shape is dominated by these two patterns often form fibrous proteins

3. Tertiary Structure: additional 3D shape that makes up most globular proteins

a. Hy d rogen Bond ing: between R groups of amino acids

b. Ionic Bond ing: between R groups of amino acids

c. Hy d rophobic E ffect: hydrophobic R groups move inward towards center of protein

d. Disulfi d e Bond s: sulfur atom of one cysteine bonds to the sulfur of another forming

cystine



4. Q uaternary Structure: describes a protein that is assembled from 2 or more separate peptidechains

a. Ex : Hemoglobin



NUCLEIC ACIDS

The genetic infor mation of a cell is stored in molecules of DN A. The DN A , in t urn, passes its genetic

instr uction to RN A for d irecting various metabolic activities of the cell

DNA: a polymer of nucleotides

Nucleotides: consists of three parts

1. Nitrogen Base

2. Deoxyribose: 5 carbon sugar

3. Phosphate Group

4 DNA Nucleotides:

1. Adenine: purine

2. Guanine: purine

3. Cytosine: pyrimidine

4. Thymine: pyrimidine

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