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45 Cards in this Set

  • Front
  • Back
What are the 4 distinctive properties of living systems?
Organisms are complicated and highly organized
Biological structures serve functional purposes
Living systems are actively engaged in energy transformations
Living systems have a remarkable capacity for self-replication
What is necessary for base pairing?
complimentary hydrogen bonding in DNA

this allows info storage and transfer
What make up 99+% of atoms in the human body?
What property unites HOC and N and renders these atoms so appropriate to the chem of life?
Their ability to form covalent bonds by e- pair sharing
What gives rise to H-bonding?
lone e- pairs on O and N
What are the varieties of C-C bond?
linear aliphatic (tetra)
Cyclic aliphatic and aromatic
What two atoms have the greatest bond energy between them?
H - H
What are the units for building complex structures?
simple molecules
Amino acids form ?
Sugars form ?
Nucleotides ?
nucleic acids
What maintains biological structure and determines biomolecular interactions?
weak forces
What are two important points about non-covalent bonds or weak forces?
biomolecular recognition is mediated by weak chemical forces
weak forces restrict organisms to a narrow range of environmental conditions
What are the four types of noncovalent interactions?
Hydrogen bonds
ionic interactions
hydrophobic interactions
van der waals interactions
Hydrogen bonds in aqueous solvent can occur between what two groups?
neutral groups ( H-O)

peptide bonds (H-N)
What are the two types of ionic interactions?
What is the smallest weak force and how much energy is needed to break the bond?
Van Der Waals: 0.4-4 kJ/mol
What is the strongest weak force and how much energy is needed to break the bond?
Hydrophobic interactions : <40 kJ/mol
How much energy does it take to break a hydrogen bond?
an ionic bond?
h-bond: 12-30 kJ/mol
ionic: 20 kJ/mol
What are hydrogen bonds?
electrostatic interactions between H donors and H acceptors
What is a H bond acceptor?
lone e- pair on atom that accepts H ions
What is a H bond donor?
a hydrogen in OH or NH2
What can never be a H donor or acceptor?
C-H: C cannot have free e-pairs
What is the most prevalent H donor and acceptor?
What is the most primary example of H bonding?
complimentary H bonding in DNA (ex between Guanine and Cytosine)
What is responsible for DNA?
the accuracy of H bonding
What imposes restrictions on folding of macromolecules so that only certain figurations can be achieved?
the linear bond that forms between the H bond donor and acceptor
What is dependent upon water?
pH and ionic equilibria
What are the properties of water? 8
high b.p
high m.p
high heat of vaporization
high surface tension
bent structure (polar molecu)
non-tetrahedral bond angles
H-bond donor and acceptor
potential to form 3-4 H bonds
What leads to the higher density of liquid water?
the h-bonds flicker and distances are shorter because h-bonds are not in a straight line
Explain the h bonds in ice.
h bonds are in a straight line, of equal lengths and constant angle, individual molecules are kept apart
How many H bonds per water does ice have?
ice: 4 H bonds, 10 microsec
water: 2.3, 10 psec
Why is water a solvent for ions?
polar nature allows it to interact with both cations and anions
forms a solvent shell
Why does NaCl dissolve in water?
water has a high dielectric constant
What is Coulomb's law?
E: force
D: dielectric constant
Why can water separate ions?
water has a high D, which is indirectly related to force. water molecules interact more strongly with ions than cations and anions can interact with ea other
What do Ions carry around when hydrated in water?
a hydration shell
what does water form with polar solutes?
h bonds
what is the secret of life?and why are they important?
hydrophobic interactions
important for structure or macromolecules and membranes
What is the hydrophobic effect?
Nonpolar (hydrophobic) molecules aggregate so that not as many h20 molecules are organized and the final S stage is increased. Entropy drives hydrophoblic interactions
What are amphilphilic molecules?
molecules that contain both polar and nonpolar groups
ex: f.a. and biological membranes
What is a clathrate?
an ordered cage that water molecules form around nonpolar molecules
What is the purpose of micelles
all hydrophobic groups are sequestered from water, the ordered shell of water molecules is min. and entropy is farther increased.
What does the colligative properties of water depend on?
number of solute molecules only
what is the limiting factor for det how high a tree can grow?
osmotic pressure
what is the H2O conc in water?
55.5 M
Why is water an electrical conductor?
Protons hop from molecule to molecule