Unit 1: chemical components of cells

mole

represents the # of molecules available to participate in chemical rxns

covalent bond

sharing of electrons

• stronger & more stable than ionic bonds

• lots of energy needed to break

• can share one or more pairs of electrons

polar covalent bond

one atom is larger than the other atom in a covalent bond

• forms a dipole; one end has partial + charge, the other has partial - charge

ionic bond

form from gain & loss of electrons

electrostatic interactions

attraction between negative and positive charges

• allow molecules to interact via complementary charges

• weak non-covalent bonds that are stronger in numbers

van der waal forces

attraction between atoms w/ uneven charge distribution

• weak, non-covalent bonds

• polarized atoms are attracted to eachother

hydrogen bonds

H—X, where X is an electronegative atom

• stronger in numbers

• how water is held together; can form spheres of hydration around ions

organic molecules

anything w/ carbon in it

• UV can break carbon covalent bonds

• cells are formed from carbon compounds

monosaccharides (sugars) →

→ polysaccharides

fatty acids →

→ fats, lipids, membranes

amino acids (form peptide bonds) →

→ proteins

nucleotides →

→ nucleic acids

macromolecules

essential biological molecules

• abundant in cells

• grow by adding monomers to one end of the polymer chain

• most ___ have polarity

ATP cycle

condensation

water expelled

hydrolysis

water consumed

polysaccharide

energy source comprised of monosaccharides

• joined by glycosidic bonds and condensation rxns

• hydrolysis rxn breaks monosaccharides apart

• two main functions in cells: storage & structure

  • storage: held in reserve for energy production

    • glycogen (animals)

    • starch (plants)

  • structure: provides mechanical support for cells

    • cellulose (plant cell walls)

    • chitin (insect exoskeleton & fungal cell walls)

oligosaccharides

help protect the cell & allow cells to interact w/ one another

• small oligosaccharides can be linked to other macromolecules

glycoprotein

sugar covalently linked to a protein

glycolipid

sugar covalently linked to a lipid

fatty acid

components of cell membranes

• more efficient at storing anergy than carbohydrates

• amphipathic: has both hydrophilic & hydrophobic regions

  • hydrophilic carboxylic acid head

  • hydrophobic hydrocarbon tail

• saturated vs unsaturated

triacylglycerol

three fatty acids held together by a glycerol molecule

• ester linkage

• storage lipids

phospholipid

hydrophilic phosphate head & hydrophobic fatty acid tails

• aggregate to form cell membranes

steroids

common multiple-ring structure

amino acid

subunits of proteins

• peptide bonds

• alpha carbon, amino group, carboxylic acid group, variable side chain

polypeptide

string of amino acids

• may or may not have a function

• N-terminus (amino terminus): has amino group (NH2), starting point

• C-terminus (carboxyl terminus): has carboxyl group (COOH, ending point (where peptides are added)

proteins

comprised of one or more polypeptides

• ALWAYS has a function

nucleoside

nitrogenous base linked to a pentose sugar

adenosine

nucleoside made of adenine attached to a ribose sugar

nucleotide

nucleoside w/ one or more phosphate (PO4) groups attached

• add to 3’ end (DNA synthesis & replication)

• subunits of DNA and RNA

  • RNA has many functions because it is single stranded & can take on many shapes

• sugar, phosphate, nitrogenous base

• can be short-term carriers of chemical energy

• held together by phosphodiester bonds in DNA and RNA

pyrimidine

six membered ring nucleotide

• thymine, cytosine, uracil

purine

5 and 6 membered rings together nucleotide

• adenine, guanine