BIO 172 UNIT 1MATERIAL QUESTIONS AND
ANSWERS
life
obeys the laws of physics and chemistry
order
organisms increase order within themselves by increasing disorder in the environment
Polar covalent bond
A covalent bond between atoms that differ in electronegativity. The shared electrons are pulled
closer to the more electronegative atom, making it slightly negative and the other atom slightly
positive.
Non-polar covalent bond
a covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting
in a balanced distribution of electrical charge. Additionally C-H is non-polar.
Ionic bond
Formed when one or more electrons are transferred from one atom to another. Weaker than
covalent bonds.
Hydrogen bonds
Very weak bonds; occurs when a hydrogen atom in one molecule is attracted to the electrostatic
atom in another molecule. These are intermolecular forces. Ex. H20. Similar to VanDerWaals
interactions. Partially positive H atom is attracted to polar molecules, usually in water. Does not
work with non-polar molecules, which are hydrophobic.
Van de Waals interaction
Weak attractions between molecules or parts of molecules that result from transient local partial
charges. Similar to H bonds. Strengthen with increasing size of molecule.
Water cohesion/adhesion
water molecules stick to each other (H bonding)
Hydrophobic
Having an aversion to water; tending to coalesce and form droplets in water. Non polar
molecules are hydrophobic and would rather stick to eachother. Like oil.
Hydrophilic
Attracted to water; polar molecules.
, Solvent
A liquid substance capable of dissolving other substances
Solute
A substance that is dissolved in a solution.
pH
Scale for acidity
electron
a negatively charged subatomic particle
amino
H-N-H
carboxyl
O=C-OH
Cysteine/Disulfide bonds
Cysteine residues (amino acids) can form disulfide bonds outside of the cytoplasm. These are
strong np covalent bonds that can only form in oxidized environments (outside of the
cytoplasm). The extracellular space can be an oxidized environment. Cysteine has a sulfhydryl
group, which can form np covalent disulfide bonds with other sulfhydryl groups.
Primary Structure
The first level of protein structure; the specific linear sequence of amino acids making up a
polypeptide chain.
Polypeptide backbone
Repeating sequence of atoms (-N-C-C-) that forms the core of a protein molecule and to which
the amino acid side chains are attached.
Quaternary structure
The fourth level of protein structure; the shape resulting from the association of two or more
polypeptide subunits. Quaternary structure is stabilized mainly by hydrophobic interactions,
hydrogen bonds, ionic bonds, and van der Waals forces between subunits, with occasional
disulfide bonds.
Tertiary structure
The third level of protein structure; the overall, three-dimensional shape of a polypeptide due to
interactions of the R groups of the amino acids making up the chain. Primary structure drives
tertiary structure.
ANSWERS
life
obeys the laws of physics and chemistry
order
organisms increase order within themselves by increasing disorder in the environment
Polar covalent bond
A covalent bond between atoms that differ in electronegativity. The shared electrons are pulled
closer to the more electronegative atom, making it slightly negative and the other atom slightly
positive.
Non-polar covalent bond
a covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting
in a balanced distribution of electrical charge. Additionally C-H is non-polar.
Ionic bond
Formed when one or more electrons are transferred from one atom to another. Weaker than
covalent bonds.
Hydrogen bonds
Very weak bonds; occurs when a hydrogen atom in one molecule is attracted to the electrostatic
atom in another molecule. These are intermolecular forces. Ex. H20. Similar to VanDerWaals
interactions. Partially positive H atom is attracted to polar molecules, usually in water. Does not
work with non-polar molecules, which are hydrophobic.
Van de Waals interaction
Weak attractions between molecules or parts of molecules that result from transient local partial
charges. Similar to H bonds. Strengthen with increasing size of molecule.
Water cohesion/adhesion
water molecules stick to each other (H bonding)
Hydrophobic
Having an aversion to water; tending to coalesce and form droplets in water. Non polar
molecules are hydrophobic and would rather stick to eachother. Like oil.
Hydrophilic
Attracted to water; polar molecules.
, Solvent
A liquid substance capable of dissolving other substances
Solute
A substance that is dissolved in a solution.
pH
Scale for acidity
electron
a negatively charged subatomic particle
amino
H-N-H
carboxyl
O=C-OH
Cysteine/Disulfide bonds
Cysteine residues (amino acids) can form disulfide bonds outside of the cytoplasm. These are
strong np covalent bonds that can only form in oxidized environments (outside of the
cytoplasm). The extracellular space can be an oxidized environment. Cysteine has a sulfhydryl
group, which can form np covalent disulfide bonds with other sulfhydryl groups.
Primary Structure
The first level of protein structure; the specific linear sequence of amino acids making up a
polypeptide chain.
Polypeptide backbone
Repeating sequence of atoms (-N-C-C-) that forms the core of a protein molecule and to which
the amino acid side chains are attached.
Quaternary structure
The fourth level of protein structure; the shape resulting from the association of two or more
polypeptide subunits. Quaternary structure is stabilized mainly by hydrophobic interactions,
hydrogen bonds, ionic bonds, and van der Waals forces between subunits, with occasional
disulfide bonds.
Tertiary structure
The third level of protein structure; the overall, three-dimensional shape of a polypeptide due to
interactions of the R groups of the amino acids making up the chain. Primary structure drives
tertiary structure.
