Microbiology Chapter 2

Atoms

smallest chemical units of matter

Atomic number

equal to the number of protons in the nucleus

Atomic mass

sum of masses of protons, neutrons, and electrons

How to calculate number of neutrons

atomic weight minus atomic number

What elements make up the majority of life?

CHON

What other elements are essential for life?

Ca, P, K, S

Isotopes

atoms of given element that differ in the number of neutrons in their nuclei

Carbon 14

radioactive because there are too many neutrons, so it is unstable

how do atoms make bonds?

using valence electrons in outermost shell

electronegativity pattern

increases from bottom to top and left to right

positive valence

if it has electrons to give up

negative valance

if it has space to fill

molecule

two or more atoms of the same element held together by chemical bonds

compound

a molecule composed of more than one element

covalent bond

sharing a pair of electrons evenly by two atoms

Preferred # of covalent bonds

SPONCH=252341

Electronegativity definition

attraction of an atom for elections (more electronegative=greater pull of its nucleus on electrons)

Nonpolar covalent bonds

atoms with similar electronegativity

Polar covalent bonds

unequal sharing of electrons due to different electronegativities

Ionic bonds

-bonds between cations and anions, more electronegative atom takes the electron

-very easy to break apart in water

hydrogen bonds

bond between partially charged H* and full or partial negative molecule

Order of bond strength

Non-polar covalent, polar covalent, ionic, hydrogen

what is the #1 reaction in Biology?

synthesis reactions

Synthesis Reactions

-formation of larger, more complex molecules

-endothermic

-aka anabolism

-create water

What is the most common type of synthesis

dehydration synthesis

Decomposition Reactions

-break bonds within larger molecules to form smaller molecules

-exothermic

-aka catabolism

-add water

Most common type of decomposition reactions

hydrolysis

Properties of water

-best solvent

-surface tension

-liquid in large range of temperatures

-large heat capacity

-present in many chemical reactions

Acids

dissociate into one or more H+ and one or more anions

Bases

binds with H+ when dissolved into water; some dissociate into cations and OH-

Electrolytes

-cation and anions of salts

-create electrical differences between inside and outside of cell

Macromolecules

-lipids

-carbohydrates

-proteins

-nucleic acids

Phosphate

Makes molecule negatively charge/polar and more likely to dissolve in water

Lipids

-non polar

-hydrophobic

-fats, phospholipids, waxes, steroids

Fat (triglyceride)

-nonpolar

-glycerol + fatty acid tail

-saturated= solid at rm temp, can tightly pack

-monounsaturated= double bonds, less hydrogen, liquid at rm temp due to kink of double bond

Phospholipid

-hydrophilic head with hydrophobic tails

-must have polarity to enter the membrane

Waxes

-insoluble in water

-lack hydrophilic head

-contain one long-chain fatty acid covalently linked to long-chain alcohol by ester bond

Steroid

-have 4 fused carbon rings

-makes membrane more stiff to make things stay in place

Carbohydrate

(CH2O)n

Monosaccharides

simple sugars, 6 carbons

Proteins

-NCC backbone

-all enzymes are protein, but not all proteins are enzymes

-antibodies are all proteins

Amino Acids

-monomer that makes up proteins

-21 total

-NCC+R

-amino (NH2) + carboxyl (COOH) + R

-R group affects how it reacts

Peptide bonds

when two amino acids come together

Conjugated Proteins

amino acids and other organic molecules

Nucleotides

Phosphate, pentose sugar, and one of five cyclic nitrogenous bases

GCAT PUPYPUPY

2121 (# of rings), 3322( # of H bonds between each other)

Purines

adenine and guanine

Pyrimidines

cytosine, thymine, uracil

DNA strand properties

-only adds at bottom of 3’ end

-5’ always attached to phosphate so nothing can attach

-5’ to 3’

-strands are complementary and antiparallel