quiz questions Flashcards
A covalent chemical bond is one in which
outer-shell electrons of two atoms are shared so as to satisfactorily fill the outer electron shells of both atoms.
An atom with atomic number 12 would have what type of chemical behavior in bonding with other elements?
It would form ions with a +2 charge
In ammonium chloride salt (NH4Cl) the anion is a single chloride ion, Cl. What is the cation of NH4Cl?
NH4, with a charge of +1
Liquid water’s high specific heat is mainly a consequence of the
absorption and release of heat when attractions due to opposite partial charges break and form.
What bond forms when the differences of electronegativity between atoms in a molecule is greater than 2.0?
an ionic bond
The atomic number of sulfur is 16. Sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound:
H2S
A double covalent chemical bond represents the sharing of how many electrons?
Four
Ice is used to cool beverages primarily because
it absorbs heat as the number of hydrogen bonds decrease from the solid to liquid state.
In condensation (dehydration) reactions, the atoms that make up a water molecule are derived from
both of the monomers.
Nitrogen-14 and nitrogen-15 are isotopes, and nitrogen-15 is used to determine protein structure. Based on this information, one can conclude that nitrogen-15 has _______ nitrogen-14.
more neutrons than
Which of the following is an impossibly covalently bonded molecule?
Oxygen can only have 2 bonds
Which of the following molecules is entirely hydrophobic?
CH4
A molecule with the formula C18H36O2 is probably a
fatty acid.
Molecules with which functional groups may form polymers via dehydration reactions?
either hydroxyl or carboxyl groups
What type of covalent bond between amino acid side chains (R groups) functions in maintaining a polypeptide’s specific three-dimensional shape?
disulfide bond
The R group or side chain of the amino acid serine is –CH2–OH. The R group or side chain of the amino acid leucine is –CH2–CH–(CH3)2. Where would you expect to find these amino acids in a globular protein in aqueous solution?
Leucine would be in the interior, and serine would be on the exterior of the globular protein.
If cells are grown in a medium containing radioactive 35S, which of these molecules will be labeled?
proteins
DNAase is an enzyme that catalyzes the hydrolysis of the covalent bonds that join nucleotides together. What would first happen to DNA molecules treated with DNAase?
The phosphodiester bonds between deoxyribose sugars and phosphate groups would be broken.
If a DNA sample were composed of 10% thymine, what would be the percentage of guanine?
40
If one strand of a DNA molecule has the sequence of bases 5’ATTGCA3’, the other complementary strand would have the sequence
5’TGCAAT3’.
What is the structural feature that allows DNA to replicate?
complementary pairing of the nitrogenous bases
Amylase, a hydrolytic enzyme, is added to a starch solution at optimal pH and temperature for the reaction. After 3 hours no starch is present. How can the experiment be changed so that there is no starch present after just 1 hour.
Add more amylase
Lipase is a digestive enzyme that catalyzes the hydrolysis of ester linkages in triacylglycerols in the small intestine. In the laboratory, how can the activity of lipase be measured?
By measuring a decline in pH due to the carboxyl group on the fatty acids.
The 1974 Nobel prize for Medicine was awarded to Gerty and Carl Cori following their isolation and characterization of the two enzymes needed for glycogen synthesis. Why are two enzymes required to produce glycogen in animals?
One enzyme catalyzes the 1,4 glycosidic bond and the other enzyme catalyzes the 1,6 glycosidic bond where the glycogen molecule branches.
