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elements
six main of these in living organisms = CHNOPS
97% human body
trace _______ (K, Fe, Na, Ca, Cl, etc) make up others
half-life
amount of time it takes for half of radioactive isotopes to decay and become more stable
used in radioactive dating
tracers
radioisotopes used to “label” and track biological molecules (ex. with viruses)
valence shell
8 valence electrons, when bonding happens
ionic bonds
transfer electrons, become negatively or positively charged
form salts (dissolves in water from broken bonds)
covalent bonds
sharing of electrons
form molecules
don’t dissolve in water (bonds NOT broken) but can separate from each other to dissolve
requires chemical reactions to break
nonpolar
share electrons equally, no partial positive or negative charge
hydrophobic
polar
do not share electrons equally, partial positive and partial negative region
hydrophilic
molecular shapes
3d, results from covalent bonding
key to function
similar have similar functions
hydrogen bonding
because water is very polar, hydrogen takes on strong partial positive and FON takes on strong partial negative
single easily broken but many are collectively strong
cohesion and adhesion
because of h bonds, cling to each other or other polar surfaces
create capillary action (“climb” narrow spaces) —> water transported up plants against gravity (transpiration)
surface tension
force created from surface molecules attracted to below molecules
water has high of this because cohesion
form droplets (max h bonds), resistant to breaking
specific heat capacity
high in water because it absorbs lots of thermal energy without a big temp change
organisms have lots of water to maintain internal temperatures, coastal habitats have more stable climates
heat of vaporization
water has high of this because liquid has to absorb a lot of heat to break h bonds
like sweat! water takes away heat when evaporated
expands
water does this when it freezes because H BONDS STABILIZE and move apart from each other
less dense as ice
insulates lake animals and keeps it from fully freezing (ice floats)
universal solvent
water is this because of polarity
blood and cells can dissolve and transport many substances
acids
more [H+], pH less than 7
bases
more [OH-], pH greater than 7
organic molecules
carbon based molecules that exist because of living things
carbon
has 4 valence electrons, forms 4 stable covalent bonds —> huge diversity of big molecules
hydrocarbon chains, branches, and rings
functional groups
replace hydrogen in carbon backbone
determine chemical reactivity and polarity
ethanol H to OH —> hydrophobic to hydrophilic
estrogen and testosterone almost the same, but have two different functional groups so have very different effects
macromolecules
organic in living things; repeating units of monomers form a polymer
dehydration reaction
monomers connect to make polymers with a covalent bond that produces a water molecule
hydrolysis reaction
breaks polymers to monomers by CLEAVING covalent bond using a necessary water molecules
enzymes
catalyst, not consumed or changed by reaction it speeds up