BIO 2040 section 2

matter

composed of elements

Chemistry

study of matter/ energy

atom

smallest functional unit of an element

molecules

forms when atoms bond with other atoms

oxygen

part of water and most organic molecules

carbon

backbone of all organic moleucles

hydrogen

part of all organic molecules and water

nitrogen

component of proteins and nucleic acids

calcium

constituent of bone, also essential for the action of nerves and muscles

phosphourous

part of cell membranes and of energy storage molecules

potassium

important in nerve action

sulfur

structural component of most proteins

sodium

primary ion in body fluids

chlorine

component of digestive acid and a major ion in body fluids

magnesium

important for action of certain enzymes and for muscle contraction

iron

constituent of hemoglobin, oxygen-carrying molecule

chemical bonds

attractive forces holding atoms together

types of chemical bonds

covalent, ionic and hydrogen

covalent bonds

- form when atoms SHARE electrons
- strongest

nonpolar covalent bonds

- electrons shared equally
EX: H2, CH4

polar covalent bonds

- electrons not shared equally
EX: H2O

ion

an electrically charged atom or molecule

positively charged ion

forms if an atom or molecule LOSES electrons

Negatively charged ion

forms if an atom or molecule GAINS electrons

Ionic bond

attractive force between oppositely charged ions (medium strength)
EX: NaCl

polar molecules

- contain polar covalent bonds in which there is unequal sharing of electrons
- electrically neutral overall, but with uneven charge distribution

hydrogen bond

weak attraction between oppositely charged regions of polar molecules (weakest)
EX: weak forces between water molecules

water

- a biological solvent in which other substances dissolve
- liquid at body temp
- transports, in blood
- helps regulate body temp by absorbing/ holding heat
- participates in chemical reactions

acid

- any molecule that can DONATE hydrogen ions (H+)
- increases hydrogen ion concentration in solutions

base

- any molecule that can ACCEPT hydrogen ions
- decreases hydrogen ion concentration in solutions

pH scale

the measure of hydrogen ion concentration
- ranges from 0 to 14 (0= most acidic)

buffers

neutralizes solutions

antacids

weak bases that neutralize stomach acid when people have heart burn

carbon makes up

18% of humans' body weight

valence

the number of covalent bonds an atom can form (usually = to # of electrons required to complete octet)

macromolecules

- are large and complex molecules that are composed of many covalently connected atoms
- are polymers made from monomers

Carbohydrates, protein, nucleic acids, lipids

categories in which macromolecules are built up using smaller molecules as building blocks

potential energy

stored energy (stored in bonds that hold atoms together)

kinetic energy

energy that is doing work

polysaccharide functions

- energy store
- structural molecules

The structure and function of a polysaccharide are determined by

- its sugar monomers
- the positions of its glycosidic linkages

polysaccharide

Thousands of monosaccharides joined in linear and/or branched chains

starch (plyscrd)

made in plants, stores energy

glycogen

made in animals, stores energy

cellulose

indigestible polysaccharide made in plants for structural support

polymer

made of many identical building blocks linked by covalent bonds

how polymers are made

Enzymes remove a hydroxyl (-OH) group from one monomer and a hydrogen (-H) from the other, then link the two monomers together and release a water molecule (H2O). Repeating this process over and over again produces a __

hydrolisis

water breakage
- breaks polymers down to monomers by addition of a water molecule
- important in digestion

lipids

- are the one class of large biological molecules that does NOT form polymers
- hydrophobic
- little or no affinity for water
- large hydrocarbon region

biologically important lipids

fats (energy storage), phospholipids (hormonal), and steroids (structure)

triacylglycerol or triglyceride

- In a fat molecule three fatty acids are joined to glycerol by ester linkages to form __
- energy-storage molecule

Saturated fatty acids

- do not have double bonds
- solid at room temperature
- includes most animal fats

Unsaturated fatty acids

- have one or more double bonds
- liquid at room temperature
- plant fats and fish fats