U1 Biochemistry

molecule

* 2 or more chemical elements make up a molecule
* smallest unit of a substance that retains chemical & physical properties of the substance

organic molecule

carbon-based; carbon atoms typically bonded together

intramolecular forces

forces within a molecule

types of intramolecular forces

* ionic
* polar covalent
* non-polar covalent

covalent bond

forms when valence electrons of 2 non-metal atoms are shared so that both may have a full valence shell

electronegativity

ability of an atom to attract electrons stronger to other atoms (e.g oxygen, nitrogen, chlorine)

dipole

a bond or molecule whose ends have opposite charges

ionic

when a metal loses electrons and non-metal gains the electrons

cation - positive ion (metal)

anion - negative ion (non-metal)

non-polar covalent

covalent bond w/ electrons being shared equally, both atoms do not possess a positive or negative charge

polar covalent

covalent bond w/ electrons being attracted to the atom of higher electronegativity (making it slightly more negative and the other atom slightly more positive)

intermolecular forces

* forces between molecules or between different parts of a molecule (if it’s large enough)
* weaker than intramolecular forces

hydrogen bond

* atom of a molecule being attracted to an atom of another molecule due to differing polarity

e.g positive hydrogen atom of a water molecule being attracted to negative oxygen atom of a water molecule

hydrophobic effect

tendency of non-polar molecules to clump together in substances

hydrophobic interaction

non-polar molecules are unable to form hydrogen bonds with other polar molecules

hydrophilic interaction

polar molecules are able to form hydrogen bonds w/ water molecules

ions

* an atom or group of atoms that loses or gains an electron to obtain a stable valence shell
* has an electrical charge

cation

* an atom that has lost an electron
* positively charged

anion

* an atom that has gained an electron
* negatively charged

molecular formula

shows the # of each type of atom in an element or compound

e.g C6H12O6

structural formula

* a diagram of a molecule that shows how atoms of the molecule are bonded together
* lines drawn between atoms indicate covalent bonds

biochemical reaction

normally involves a combination of more than one

4 main chemical reactions biological molecules undergo

neutralization

oxidation-reduction

condensation

hydrolysis

acid

* substance that produces hydrogen ions (H^+) when it dissolves in water
* increases concentration of ions in an aqueous solution

base

* substance that produces hydroxide ions when it (OH^-) when it dissolves in water
* increases concentration of hydroxide ions
* can be thought of as a substance that accepts or reacts with hydrogen ions

pH scale

ranking of substances according to the relative concentration of their hydrogen ions

neutralization

* acid-base reaction
* acid interacts w/ a base resulting in salt (ionic compound) & water
* both acid & base lose their acidic & base properties respectively

buffers

substances that minimize changes in pH by donating or accepting hydrogen ions as needed

oxidation

when a molecule loses an electron & becomes oxidized

reduction

when a molecule accepts electrons from an oxidized molecule

oxidation-reduction

* oxidation & reduction occurs at the same time so the whole reaction is termed this
* redox reaction

condensation

* hydrogen is removed from a functional group on one molecule
* an OH group is removed from another molecule
* the 2 molecules bond and form a larger molecule & water
* all 4 types of biological macromolecules involve this reaction between the monomers of each polymer

hydrolysis

* breaks down macromolecules into monomers in cells
* hydrogen from water is added to one monomer
* an OH group is added to another monomer beside it
* covalent bond between these 2 monomers breaks & the larger molecule is split into 2 smaller molecules

isomer

a molecule with the same molecular formula but different structure

monomer

molecule that can bond to other identical molecules to form a polymer

polymer

molecule made of multiple monomers

4 main types of macromolecules

carbohydrates

lipids

proteins

nucleic acid

carbohydrates

* contains carbon, hydrogen and oxygen
* easy-to-access energy
* polar; soluble in water
* e.g sugar & starches

types of carbohydrates

monosaccharide

disaccharide

polysaccharide

glycosidic linkage

covalent bond b/w 2 monosaccharides

forms b/w specific hydroxyl groups on each mono saccharide

hexose

* 6 carbon sugar
* A glucose, B glucose, galactose, fructose

pentose

* 5 carbon sugar
* ribose, deoxyribose

monosaccharide

* # C atoms in molecule 3-7
* composed of a single carbon-based monomer
* a monomer for other carbohydrates
* A glucose, B glucose, galactose, fructose

disaccharide

* 2 monosaccharides covalently bonded
* maltose, sucrose, lactose

polysaccharide

monosaccharides joined together by glycosidic linkage

starch, glycogen, cellulose