Chapter 2: Chemical Principles

inorganic compounds

small, simple molecules (no C)

• ex. H2O, O2, salts, acid & bases

organic compounds

large, structurally complex (yes C)

• covalent bonds

• CHON

• carbo skeleton + functional group

alcohol/hydroxyl

—OH

lipids, carbs

amino

—NH2 (has N)

proteins

carboxyl

—COOH

organic acids, lipids, proteins

phosphate

has P

ATP, DNA

dehydration synthesis

build-up of molecules (compound)

• small monomers → one large polymer

• MAKE covalent bonds + H2O (released)

hydrolysis

breakdown of molecules

• one large polymer → small monomers

• BREAK COVALENT bonds + H2O (input)

major organic compounds

carbs, lipids, proteins, nucleic acids

carbohydrate

aka sugars (C,H,O) “-ose”

• monosaccharides = building blocks

monosaccharides

“simple sugars” 3-7 C (building blocks)

• fxn: quick source of energy (glucose→humans)

• ex: fructose, glucose, deoxyribose (DNA)

• sweet-taste, water-soluble

disaccharaides

2 monosaccharides form glycosidic (covalent) bonds via dehydration syn.

• fxn: structural component for bacterial cell walls

• ex: sucrose, lactose

  • glucose + fructose → sucrose + H2O

polysaccharides

tens/hundreds of monosaccharides joined via dehydration syn.

• fxn: long-term energy source; structure for plant cell walls

• ex: starch (plant), glycogen (human), cellulose (plant cell wall)

  • all polymers of glucose

proteins

• CHON (sometimes S)

• cell structure → function (most diverse)

ex & fxn:

• structural protein: keratin (reinforce skin against infection)

• transporter protein: proteins in cell membrane (channels/carriers)

• enzymes: speed up chem rxns

• antibodies: involved in immune response

• bacterial toxins: poisonous proteins made by some bacteria

amino acids

proteins’ subunits (20 types)

• central carbon attached to:

  • amino group, carboxyl group, hydrogen, side (R) group

  • two groups contain sulfur

peptide bonds

covalent bond between amino acids (via dehydration syn.)

denaturation

protein loses/changes shape → loses/changes function

• d/t harsh/hostile environments (↑ temp/ ↓ pH) may be permanent

primary

sequence of a.a. in linear structure (simple fxn)

secondary

a.a. chain folds/coils in helix/pleated sheet

• d/t H bonds (weak bonds)

• ex. hair protein (helix); skin protein (pleated sheet)

tertiary

helix/pleated sheet irregularly (forms disulfide bridges, H bonds, ionic bonds between a.a.)

quaternary

two or more polypeptide (protein) chains bound to each other (2 or more 3° subunits)

• ex. hemoglobin, antibodies, enzymes

what are the building blocks of enzymes?

amino acids (protein)

lipids

CHO

• triglycerides = subunits

• primary part of cell membranes

simple lipids (fats or triglycerides)

1 glycerol + 3 fatty acid chains

• ester bond = covalent bond (via dehydration syn.)

• saturated fatty acids: no double bonds

• unsaturated fatty acids: one or more double bonds

• key fxn: alt. source energy when no carbs

complex lipids

cell membranes made of phospholipids (1 glycerol, 2 fatty acid chains, 1 phosphate group)

• polar head = charged

• non-polar tail = uncharged

fxn:

• structural components: form phospholipid bilayer of cell membrane

• regulation of transport: controls what enters & leaves cell → homeostasis

steroids

three 6-carbon rings + one 5-carbon ring

• key fxn: structural in cell membrane of eukaryotic cells

• cholesterol, hormones, some vitamins

sterol

“—OH” attach to one 6-carbon

• cholesterol: sterol in animal cell

• phytosterol: sterol in plant cell

• ergosterol: sterol in fungi cell

nucleic acids

CHON

• nucleotides (building blocks)

• phosphodiester bond (covalent bond)

nucleotide

sugar (5-carbon pentose)

• phosphate group

• base: nitrogen-containing base

  • purine bases: A & G

  • pyrimidine: C, U, T

DNA

double-stranded molecule (double helix)

• sugar-phosphate backbone

• A-T, C-G base pairing

• fxn: store genetic info

RNA

usually single-stranded molecule

• sugar-phosphate backbone

• no base pairing

• mRNA, tRNA, rRNA

• fxn: protein synthesis

ATP

adenosine triphosphate

• nitrogenous base (A) + sugar (ribose) + 3 phosphate groups

• remains “single nucleotide”

• high energy compound

  • released by hydrolysis of phosphate groups