Biology 2: Biochem Flashcards
Molecule
2 or more atoms joined together.
Atoms bond with other atoms…
to become more stable and to fill their outer energy levels
Ionic Bond
one atom “steals” electron from another
Covalent Bond
atoms “share” electrons
Polar Molecule
molecule with a positive and a negative end
it’s atoms do not share electrons equally
Hydrogen Bond
the hydrogen (positive) end of a polar molecule is attracted to the negative end of another molecule (often O or N)
Cohesion
polar water molecules are attracted to each other, and this creates surface tension
Adhesion
polar water molecules are attracted to other polar molecules
Surface Tension
caused by cohesion, “skin” on the surface of water
Cohesion + Adhesion
keeps molecules organized inside cells
allows H2O to move against gravity in plants
Temperature Moderation
adding heat makes molecules “twitch” faster
hydrogen bonds moderate movement
areas near water have a more stable climate
evaporation helps organisms maintain homeostasis
Low density of ice
lose thermal energy => molecules slow down => H bonds lock them in place in a grid => molecules are farther apart, so they are less dense and the ice floats
Water is good at dissolving because…
it’s polar!
Solution
uniform combination of two or more substances
Solute
thing that gets dissolved
Solvent
thing that does the dissolving (pulls ions away)
Polar charges…
on H2O molecules are attracted to charted regions of other polar molecules
For something to dissolve,
the attraction to water must be greater than the attraction to itself
The solvent used by organisms…
water
In solutions…
a few H2Os split into ions
Acids
pH<7 add H to solution
Bases
pH>7 remove H from solution