Ch 2. Chemical Principles Flashcards
Chemistry
the study of interactions between atoms and molecules
Atom
the smallest unit of matter and cannot be subdivides into smaller substances
atoms interact to form
molecules
electrons
negatively charged particles
protons
positively charged particles
neutrons
uncharged particles
Chemical element
atoms with the same number of protons
Atomic number
number of protons in the nucleus
Atomic mass
total number of protons and neutrons in an atom
Isotopes
atoms with different numbers of neutrons
Electron shells
electron arrangement corresponding to diff. energy levels
Valence
number of missing or extra electrons in the outermost shell
Chemical bonds
valence electrons holding molecules together
a compound
a molecule that contains two or more kinds of atoms (H2O)
Ionic Bonds when…
protons and electrons are equal
Ions
charged atoms that have gained or lost electrons
Cations
atoms that lose electrons and become positively charged ions
Anions
atoms that gain electrons and become neg, charged
Ionic bonds
attractions between ions of opposite charge
Covalent bonds
form when two atoms share one or more pairs of electrons
covalent bonds are…
stronger and ore common in organisms than ionic bonds
Hydrogen bonds
when a hydrogen atom that is covalently bonded to an O or N atom is attracted to another N or O atom in another molecule
Molecular mass
sum of the atomic masses in a molecule
One MOLE of a substance
is its molecular mass in grams
Dalton (da)
unit of molecular mass
Chemical rxns
involve the making or breaking of bonds between atoms
a change in Chemical energy occurs
during a chemical rxn
Endergonic
reactions absorb energyE
Exergonic
reactions release energy
Synthesis reactions
occurs when atoms, ions, or molecules combine to form new, larger molecules
Anabolism
the synthesis of molecules in a cell
Decomposition Reactions
occur when a molecule is split into smaller molecules, ions, or atomsC
Catabolism
decomposition reaction sin a cell
exchange reactions
part synthesis and decomposition
Reversibility of Chemical Reactions
- can readily go in either direction
- each direction may need special conditions
Organic Compounds
always contain carbon and hydrogen; typically structurally complex
Inorganic compounds
typically lack carbon; usually small and structurally simple
Dissociations
seperation
Acids
substances that dissociate into one or more hydrogen ions and one or more neg ions
bases
substances that dissociate into one or more hydroxide ions and one or more pos ions
salts
Substances that dissociate into cations and anions,
neither of which is orH+OH−
conc of H+ is a solution is expressed
as pH
pH =
-log(10)[H+]
increasing [H+]
increases acidity
increasing [OH-]
increases alkalinity
pH 6.5 and 8.5
most organisms grow best
Carbon skeleton
chain of carbon atoms in an organic molecule
functional groups
bond to carbon skeletons and are responsible for most of the chemical properties of a particular organic compound
Macromolecules
polymers consisting of many small repeating molecules
monomers
small repeating molecules
monomers join by
dehydration synthesis or condensation reactions
isomers
molecules with same chemical formula, but different structures
Monosaccharides
simple sugars with three to seven carbon atoms
Disaccharides
formed when two monosaccharides are joined in a dehydration synthesis
disaccharides can be broken down by
hydrolysis
Polysaccharides
consist of tens or hundreds of monosaccharides joined through dehydration synthesis
Lipids
- Primary components of cell membranes
- Consist of C, H, and O
- Are nonpolar and insoluble in water
Simple lipids
Fats or triglycerides
* contains glycerol and fatty acids; formed by dehydration synthesis
Saturated fat
no double bonds in fatty acids
Unsaturated fat
one or more DB in the fatty acids
Cis
H atoms on the same side of the DB
Trans
H atoms on opposite sides of the DB
Complex Lipids
- Contain C, H, and O + P, N, and/or S
- Cell membranes are made of complex lipids called
phospholipids
– Glycerol, two fatty acids, and a phosphate group - Phospholipids have polar as well as nonpolar regions
Steroids
- Four carbon rings with an group attached to one
ring - Part of membranes that keep the membranes fluidOH−
Proteins
- Made of C, H, O, N, and sometimes S
- Essential in cell structure and function
– Enzymes that speed up chemical reactions
– Transporter proteins that move chemicals across
membranes
– Flagella that aid in movement
– Some bacterial toxins and cell structures
Amino Acids
Amino acids contain an alpha-carbon that has an
attached:
– Carboxyl group (-COOH)
– Amino group (NH2)
– Side group
proteins consist of subunits called
amino acids
Stereoisomers
D or L
L most often found in nature
peptide bonds
between amino acids are formed by dehydration synthesis
Secondary structure
occurs when the amino acid chain folds and coils in a helicopter or pleated sheet
Tertiary structure
occurs when the helix or sheet folds irregular, forming disulfide bridges, hydrogen bonds, and ionic bonds btwn amino acids in the chain
Quaternary Structure
consist of two or more polypeptides
Denaturation
occurs when proteins encounter hostile
environments such as temperature and pH, and
therefore lose their shapes and functions
Conjugated proteins consist of amino acids and other organic molecules
*Glycoproteins
*Nucleoproteins
*Lipoproteins
Nucleic Acids
consist of nucleotides
Nucleotides consist of
- A five-carbon (pentose) sugar
- Phosphate group
- Nitrogen-containing (purine or Pyrimidine) base
Nucleosides consist of
- Pentose
- Nitrogen-containing base
DNA (Deoxyribonucleic acid)
– Contains deoxyribose
– Exists as a double helix
– Adenine hydrogen bonds with Thymine
– Cytosine hydrogen bonds with Guanine
* Order of the nitrogen-containing bases forms the
genetic instructions of the organism
RNA (Ribonucleic acid)
– Contains ribose
– Is single-stranded
– Adenine hydrogen bonds with Uracil
– Cytosine hydrogen bonds with Guanine
* Several kinds of RNA play a specific role in protein
synthesis
Adenosine triphosphate (ATP)
made of ribose, adenine, and three phosphate groups
ATP Stores ….
the chemical energy release by some chemical reactions
ATP Releases…
phosphate groups by hydrolysis to liberate useful energy for the cell
