3.1 - The chemistry of life Flashcards
how is energy for many cellular reactions derived?
hydrolysis of high-energy phosphoanhydride bonds of ATP -> ADP + Pi (and ADP -> AMP +Pi)
how are covalent bonds made/broken?
enzymes
when is bond rotation not possible in covalent bonds?
double bonds (alkenes)
what are stronger ionic bonds or covalent?
covalent
how does water dissolve ion crystals?
electrostatic interactions between anion, cation and partial charges on water. partial negative charge of O -> cation, partial positive charge of H -> anion. Forms hydration shell of H2O molecules around anion/cation
what allows macromolecules to form correct shapes?
non-covalent bonds between different parts of macromolecule
electronegativity
power of attraction atom has for the bonding of electrons
generally larger = more electronegativity
negatively charged ion
anion
positively charged ion
cation
what bonds are polar? (2)
- OH
- NH
what bond is non-polar?
CH
dipole
when nucleus of one atom in molecule attracts e- more strongly than the other (creates slight +ve and -ve charge on opposite sides of molecule)
what molecules can interact with water? (2)
- molecules containing OH groups
- molecules containing NH groups
what molecules cant interact with water?
molecules containing CH group (hydrophobic)
what compounds/molecules will water dissolve? (2)
- ionic compounds
- polar molecules
H-bond formation
between any H atom covalently bonded to a more electronegative atom/group or other electronegative atom bearing lone e- pair
common H-bond atoms (when bonded to H) (2)
- O
- N
what do H-bonds confer?
flexibility
Hydrophobic effect (3)
- interaction of non-polar molecules/components in aqueous solution
- non-polar portions aggregate (fewer H2O molecules ordered + entropy increases)
- non-polar groups sequestered from water, released H2O molecules increase entropy further
folding of globular proteins
hydration layer around polypeptide minimised by hydrophobic non-polar amino acids (gathered toward interior of folded protein - hydrophobic)
where do hydrophobic components gather in elements of the cell?
towards interior
what are the strengths of the 4 noncovalent forces? (2)
- constantly form/reform
- confers great flexibility/stability in biomolecules despite relative weakness of forces
molecular complementarity
charges, polarity and hydrophobicity of 2 protein surface shapes permit multiple weak interactions that combined can form specific, weak/strong, transient/stable interactions
form structural elements in cell walls of bacteria and plants, lubricate skeletal joints and involved in cell recognition/adhesion
carbohydrates
