Unit 2: Key terms A and P
Matter
anything that has mass and occupies space (solid, liquid, gas)
Atom
smallest unit of matter that retains original properties, made up of even smaller structures called subatomic particles (protons, neutrons, electrons)
Atomic number
number of protons in atomic nucleus: defines every element
Element
substance that cannot be broken down into simpler substance by chemical means, each element is made of atoms with same number of protons
Major elements in the human body
Human body is made up of 4 major elements (hydrogen, oxygen, carbon, nitrogen)
Mixtures: Suspension
a heterogeneous mixture of a finely distributed solid in a liquid
Mixtures: Colloid
two or more substances mixed together but not chemically combined
Mixtures: Solution
a homogeneous mixture of one or more solutes dissolved in a solvent
Chemical bonds
matter can be combined chemically when atoms are combined
Molecule
formed by chemical bonding between two or more atoms
Compound
formed when two or more atoms from different elements combine by chemical bonding
Ionic bond
electrons are transferred between atoms: results in formation of ions (cations and anions)
Cation
positively charged ion: loses one or more electrons
Anion
negatively charged ion: gains one or more electrons
Covalent bond
strongest bond: two or more nonmetals share electrons (single, double, or triple bonds)
Nonpolar covalent bonds
two nonmetals in molecule with similar or identical electronegativity pull with equal force, share electrons equally
Polar covalent bonds
nonmetals with different electronegativities share electrons unequally, atom with higher e becomes partially negative, atom with lower e becomes partially positive
Hydrogen bonds
weak attractions between the partially positive end of one dipole and the partially negative end of another dipole, responsible for the key property of water-surface tension
Hydrophilic solutes
only able to dissolve hydrophilic solutes (with fully or partially charged ends)"like water": water dissolves ionic and polar covalent solutes
Hydrophobic solutes
do not have full or partially charged ends: do not dissolve in water: include uncharged nonpolar covalent molecules ex: oils and fats
Chemical reaction
when chemical bond is formed, broken, or rearranged, or electrons are transferred between two or more atoms (or molecules)
Chemical notation
series of symbols and abbreviations demonstrates what occurs in a reaction
Chemical equation
basic form of chemical notation
Reactants
starting ingredients: will undergo reaction (left side of equation)
Products
results of chemical reaction (right side of equation)
Catabolic reaction (decomposition reactions)
AB --> A +B
Exchanged reactions
AB + CD --> AD + BC
Anabolic reactions (synthesis reactions)
A +B --> AB
Reaction Rates
for reaction to occur atoms must collide with enough energy to overcome repulsion of their electrons
Activation energy (Ea)
energy required for all chemical reactions
Enzymes
biological catalysts: increases the reaction rate by lowering activation energy: not consumed or altered in reaction
Substrates
substance that can bind to enzymes active site (highly specific)
Biochemistry
chemistry of life
Inorganic compounds
generally do not contain carbon bonded to hydrogen: water, acids, bases, and salts
Organic compounds
do not contain carbon bonded to hydrogen
Monomers
single subunits
Polymers
monomers combined to build larger structures
Carbohydrates
composed of carbon, hydrogen, and oxygen: function primarily as fuel: some limited structural roles
Monosaccharides
monomers from which all carbohydrates are made (glucose, fructose, galactose, ribose, and deoxyribose are most abundant)
Disaccharides
formed by union of two monosaccharides
sucrose --> glucose +frutose
Polysaccharides
many monosaccharides joined to one another by dehydration synthesis reactions
Glycogen
storage polymer of glucose: mostly in skeletal muscle and liver cells
Starch
storage polymer of glucose in plants
Cellulose (fiber)
we don't have the enzymes to break apart the linages between the sugars in cellulose
Lipids
group of nonpolar hydrophobic molecules composed primarily of carbon and hydrogen: include fats and oils
Fatty acids
lipid monomers
Saturated fatty acids
solid at room temp, no double bonds between carbon atoms, carbons are "saturated" with maximum number of hydrogen atoms
Monosaturated fatty acids
generally liquid at room temperature, one double bond between two carbons in hydrocarbon chain
Polyunsaturated fatty acids
liquid at room temp, two or more double bonds between carbons in hydrocarbon chain
Triglyceride
3 fatty acids linked by dehydration synthesis to modified 3-carbon carbohydrate
Phospholipids
glycerol backbone, two fatty acid "tails", one phosphate "head" in place of 3rd fatty acid
Amphiphilic
nonpolar group (fatty acid tail), molecule with polar group is phosphate head, makes phospholipids vital to structure of cell membranes
Steroids
nonpolar: share four-ring hydrocarbon structure called steroid nucleus
Cholesterol
steroid that forms basis for all other steroids
Proteins
made of carbon, oxygen, hydrogen, and nitrogen, the most abundant cell components
R groups
give amino acids different chemical properties
Amino acid
monomer subunit
Primary structure
amino acid sequence of polypeptide chain
Secondary structure
one or more segments of primary structure folded in specific ways: help together by hydrogen bonds
Alpha helix
coiled spring
Beta-pleated sheet
venetian blind
Tertiary structure
three-dimensional shape of peptide chain, stabilized by hydrogen bonding
Quaternary structure
linking together more than one polypeptide chain in a specific arrangement: critical to function of protein
Protein denaturation
Destroying protein's shape by heat, ph changes, or exposure to chemicals, disrupts hydrogen bonding and ionic interactions that stabilize structure and function
Nucleotides
monomer of nucleic acids, make up genetic material
Nucleic acids
composed of nucleotides, a complex organic substance present in living cells
Nucleotide structure
nitrogenous base with hydrocarbon ring structure, five-carbon pentose sugar, phosphate group
Nitrogenous base: Purines
double-ringed molecule: adenine(A) or guanine (G)
Nitrogenous base: Pyhimidlines
single-ringed molecule: cytosine (C), uracil (U), and thymine (T)
DNA structure "Legs of ladder"
phosphate and sugar backbone
DNA structure: "Rungs of ladder"
nitrogenous base (A, T, C, or, G)
DNA
extremely large molecule in nuclei of cells, composed of two long chains that twist around each other to form double-helix
Double-helix
held together by hydrogen bonding between the bases of each strand
Genes
recipe(code) for protein synthesis
Protein synthesis
process to make every protein
RNA
contains ribose, instead of deoxyribose sugars, single-stranded, thymine replace by uracil
Protein synthesis: TransCription
copies genetic information from DNA to RNA, occurs in nucleus
Protein synthesis: TransLation
reads information in RNA to produce proteins, occurs in cytoplasm