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Ch.2 Chemical Basis of Life
I.
Inorganic Molecules (p. 44)
A.
Water - ~ 70% of body wt
1.
Properties of water (Figs. 2-8, 2-9, 2-10; Table 2-2)
a. polarity - allow water to act as
effective solvent. (universal solvent)
b. tends to ionize substances in solution
c. major transport medium
d. high specific heat - high heat absorption w/o much change in temp
e. High heat of vaporization - absorption of significant amts of heat to chg water
from a liquid to a gas
B.
Electrolytes - substances that can break up, or dissociate, in solution to form ions
1.
Acids - release H when in solution
a. taste sour
b. AKA proton donors
c. HCl => H + Cl
d. litmus paper will turn red
2.
Bases - or alkaline compounds, when dissociated in soln, shift the H /OH balance
in favor of OH
a. combine or accept H ions - proton acceptor
b. taste bitter
c. NaOH => Na + OH
d. another important base - HCO3
e. litmus paper will turn blue
3.
pH scale (Fig. 2-12) - negative log of H conc.
a. indicates degree of acidity or alkalinity of solution
b. High pH - basic (low H ), pH 8-14
c. Low pH- acidic (high H ), pH 1-6
d. 7 - neutral
e. pH: scale 1-14
4.
Buffers - minimize changes in the concentration of H and OH to maintain
constant pH in body
5.
Salts (Tables 2-1, 2-3)-compd that result from chem. rxn of acid and base
a. neutralization reaction:
HCl + NaOH => NaCl + H2O
II.
Metabolism (Fig. 2-25) – all of the chemical reactions that occur in body cells
A.
Catabolism – chemical rxns (usually Hydrolysis reactions)
Break down larger food molecules into smaller chem. units; release energy
B.
Anabolism - chemical rxns (usually dehydration reactions)
1.
Build larger and more complex molecules; require energy
2.
ex.- Proteins (Table 2-5)- contains C, O, H, N
a. most abundant organic molecule in body
b. Draw Structure
c. peptide bonds – joins amino acids together
d. dehydration synthesis- joining of polymers results in loss of water molecule
C.
Adenosine triphosphate (ATP) (Fig. 2-26)
1.
composed of ribose, adenine, & 3 phosphate subunits
2.
high energy bonds – energy transferred to newly formed compounds
3.
energy stored in ATP used for – muscle contraction & movement, active
transport, and biosynthesis