Medical Microbiology - Chapter 3 - Basic Chemistry
I. Basic Chemistry
A. Atoms - all matter composed of atoms
1. nucleus - protons, neutrons
2. electrons orbit nucleus
B. Elements - contain only 1 kind of atom
1. Periodic Table - arranged according to reactivity
2. Elements in living matter
a. 20
b. 4 make up 97% of all living matter; rest called trace elements
C. Molecules - 2 or more atoms bonded together
D. Compounds
1. 2 or more atoms joined together in a definite proportion by weight
2. properties of reactants different than product
3. formula represents cpds.
4. 2 types of cpds.: inorganic and organic
E. Solutions - where one substance is dissolved into another
1. Solute - substance dissolved
2. solvent - substance that does the dissolving
3. soluble - substance can be dissolved
4. insoluble - substance can't be dissolved
5. Water is universal solvent - polar
6. Tincture - where a substance is dissolved into alcohol
II. Acids, Bases, and Salts
A. Acid
- substance that ionizes in water into positively charged Hydronium ions (H3O+)
B. Base
- substance that ionizes in water into negatively charged Hydroxide (OH-) ions
C. Neutralization and Salts
1. acid + base → salt + water - called neutralization
2. example: HCL + NaOH → NaCL + H2O
ions of acid and ions of base join to form water and salt
III. Indicators - special chemicals used to test for H+ ion concentration in solutions
- examples of indicators:Blue litmus paper - blue in base; red in acid
Bromthymol Blue - blue in base; yellow in acid
Phenolphthalein - pink in base; colorless in acid
IV. pH of Living Organisms - not too acid or too base
A. pH - measure of acidity
B. pH scale - 7 neutral
0-6.9 - acid
7.1-14 - base
-tears 7.3, blood 7.4, urine 5-7.5
C. Biochemical reactions
1. must occur at given pH
2. deviation could be disastrous and/or fatal
D. Buffers
1. maintain pH balance
2. either donate or accept H+ ions
V. Types of compounds
A. Inorganic
1. don't have carbon
2. exceptions: CO2 and CaCO3
B. Organic
1. large and complex
2. have C, H, O, and usually N and P
3. hydrocarbons - consisting only of carbons and hydrogens
VI. Carbohydrates
A. contain C, H, and O in ration of 1:2:1
B. Monosaccharides
1. simple sugar - can't be broken down any further
2. 3 monosaccharrides
a. glucose - C6H12O6
b. fructose (fruits and honey)
c. galactose (flaxseed, agar, milk)
3. isomers - same molecular formula but different structure
4. Glucose used by living organisms to produce energy - ATP (adenosine triphosphate)
a. oxidation: glucose + oxygen → ATP
b. oxidation - any reaction that involves oxygen or any reaction that causes an atom to
lose electrons
C. Disaccharides
1. 2 sugars bonded together
2. bonding occurs by dehydration synthesis
3. examples:sucrose (table sugar) - glucose + fructose
lactose (milk sugar) - glucose + galactose
maltose (malt sugar) - glucose + glucose
4. bonds broken by hydrolysis
D. Polysaccharides
1. huge polymer
2. examples:starch - storage form of glucose in plants
cellulose - found in cell wall - very strong and rigid
glycogen - (animal starch) storage form of glucose in liver/muscles of animals
chitin - exoskeleton of invertebrates
VII. Lipids
A. Characteristics of Lipids
1. ratio of hydrogen to oxygen - lots of hydrogen, less oxygen
2. fats, oils, waxes
3. gram for gram, fat produces more energy than sugar (carbs)
4. 3 categories of lipids: simple, compound, derived
5. general structure: 1 glycerol molecule + 3 fatty acid molecules
6. formed by dehydration synthesis
B. Simple - C, H, and O
1. fats and oils
2. ex.: butter, margarine, bees wax, lanolin, oils - corn, safflower, olive, peanut
3. 2 types of simple lipids
a. saturated
-all C bonds are single covalent bonds - b/c bonds are saturated with H
-fatty acid tails straight - pack tightly together
-solid at room temperature (b/c of single covalent bonds between the carbons)
- bad for you - raise cholesterol levels in blood
b. unsaturated
-in some of C bonds, 2 H bonds replaced with double bonds between C atoms (C-C)
-causes bump in fatty acid tails - tails can't pack tightly
-more double bonds you have, more unsaturated it is (polyunsaturated)
-liquid at room temperature
-good for you - lowers cholesterol levels in blood; easier to digest
C. Compound - C, H, O, N, and P
1. amount remains constant in organism
2. phospholipids in cell membrane
3. glycolipids in brain and nerve cells
D. Derived - C, H, O
1. steroids found in male and female hormones
2. Vitamin D
3. cholesterol
4. fat soluble vitamins: A, D, E, and K
5. called lipids because soluble in fat solvents
VIII. Proteins - C, H, O, N, and S
-most diverse and essential organic cpd. in all living organisms
-made of amino acids bonded together
A. Amino acids
1. 20 total
2. basic structure
a. central carbon - C
b. amino group - NH2
c. carboxyl group - COOH
d. radical (R) group - what makes every amino acid different
B. peptide bond
1. bond between amino acids
2. 300-1'000's amino acids bonded together to form protein; bond between C of one
amino acid and N of other amino acid
3. polypeptide
C. 4 structural levels of protein
1. primary
-structure - straight chain
2. secondary
a fibrous proteins - strong/stable
b. structure-alpha helix
- beta pleated sheets
c. examples: hair, nails
3. tertiary
a. structure - globular protein - one protein folds forming globs of amino acids
b. examples - enzymes
4. quaternary
a. structure - 2 or more globular proteins bonded together
b. examples - hemoglobin
D. Enzymes
1. all enzymes are proteins
2. organic catalyst - speed up chemical reaction but itself remains unchanged
3. causes chemical reaction to occur at right time
4. composition of enzymes
a. protein or part protein molecule + nonprotein
b. apoenzyme - protein part
c. coenzyme - nonprotein part (ex.: Ca, Fe, Mg, Cu, vitamins C and B-complex)
5. highly specific
6. enzyme-substrate complex
a. active site on enzyme
b. substrate - substance enzyme reacts with
IX. Nucleic Acids
A. C, H, O, N, and P
B. 2 types
1. DNA
2. RNA
C. Chromosomes and Genes - genes on chromosomes
D. Structure
1. made of smaller subunits - nucleotides
2. nucleotides
a. 5 C sugar - deoxyribose or ribose
b. phosphate group
c. N2 base
-purines: adenine and guanine
-pyrimidines: cytosine, thymine, and uracil
-bonding specific: A-T (U); C-G
E. DNA - deoxyribonucleic acid
1. location - nucleus, mitochondria, cell membrane, chloroplasts
2. structure
a. double stranded (double helix0
b. 5 C sugar - deoxyribose
c. phosphate group
d. four N2 bases: A-T and C-G
3. function - carries genetic information
F. RNA - ribonucleic
1. location - nucleus, cytoplasm, ribosomes
2. structure
a. single stranded
b. 5 C sugar - ribose
c. four N2 bases: A-U and C-G
3. function - essential for protein synthesis
4. 3 types
a. mRNA
b. tRNA
c. rRNA