Ch.1 - Biochemistry Berg Exam Questions with Answers
Latest Update
Show a timeline of the Earth showing when oxygen formed, microorganisms,
macroscopic organisms, cells with nuclei, dinosaurs, and human beings formed. -
Correct Answer 1001
How is DNA classified as a chemical? - Correct Answer DNA is a linear polymer
made up of four different types of monomers. It has a fixed backbone from which
protrude variable substituents, referred to as bases (1002).
What is the backbone of DNA made of? - Correct Answer The backbone is built of
repeating sugar-phosphate units. The sugars are molecules of deoxyribose from
which DNA receives its name. Each sugar is connected to two phosphate groups
through different linkages. Moreover, each sugar is oriented in the same way, and so
each DNA strand has directionality, with one end distinguishable from the other.
Joined to each deoxyribose is one of four possible bases: adenine (A), cytosine (C),
guanine (G), and thymine (T). 1002
Draw Adenine bonded to its pair. - Correct Answer 1003
Draw Thymine bonded to its pair. - Correct Answer 1003
Draw Guanine bonded to its pair. - Correct Answer 1004
Draw Cytosine bonded to its pair. - Correct Answer 1004
Describe the key to the functionality of the double helix structure of DNA. - Correct
Answer The key to this structure is that the bases form specific base pairs (bp) held
together by hydrogen bonds: adenine pairs with thymine (A-T) and guanine pairs
with cytosine (G-C). Hydrogen bonds are much weaker than covalent bonds such as
the carbon- carbon or carbon-nitrogen bonds that define the structures of the bases
themselves. Such weak bonds are crucial to biochemical systems; they are weak
enough to be reversibly broken in biochemical processes, yet they are strong
enough, particularly when many form simultaneously, to help stabilize specific
structures such as the double helix.
What enables the copying mechanism of DNA? - Correct Answer Because of base-
pairing, the sequence of bases along one strand completely determines the
sequence along the other strand. As Watson and Crick so coyly wrote: "It has not
escaped our notice that the specific pairing we have postulated immediately
suggests a possible copying mechanism for the genetic material." Thus, if the DNA
, double helix is separated into two single strands, each strand can act as a template
for the generation of its partner strand through specific base-pair formation. 1005
Through what kind of bonding does A connect to T? - Correct Answer 2 hydrogen
bonds
Through what kind of bonding does C connect to G? - Correct Answer 3 hydrogen
bonds
What's the bond length and energy of a C-C bond? - Correct Answer 1.54
Angstroms and bond energy of 355 kJ/mol (85 kcal/mol).
Draw the resonance of adenine. - Correct Answer 1006
How many nm is an angstrom? - Correct Answer an angstrom is 0.1 nm
How does the strength of noncovalent bonds compare to the strength of covalent
bonds? - Correct Answer Noncovalent bonds are weaker than covalent bonds.
What's the energy of an ionic interaction in the form of an equation? - Correct
Answer 1007
An attractive interaction has positive or negative energy? - Correct Answer By
convention, an attractive interaction has a negative energy. The ionic interaction
between two ions bearing single opposite charges separated by 3 Å in water (which
has a dielectric constant of 80) has an energy of -5.8 kJ/mol (-1.4 kcal/mol).
Describe the ionic interaction between two ions bearing single opposite charges in
water and in hexane. - Correct Answer The ionic interaction between two ions
bearing single opposite charges separated by 3 Å in water (which has a dielectric
constant of 80) has an energy of -5.8 kJ/mol (-1.4 kcal/mol). Note how important the
dielectric constant of the medium is. For the same ions separated by 3 Å in a
nonpolar solvent such as hexane (which has a dielectric constant of 2), the energy of
this interaction is -232 kJ/mol (-55 kcal/mol).
How does the dielectric constant of water compare to that of hexane? - Correct
Answer The dielectric constant of water is 40 times greater.
What's the hydrogen-bond donor and acceptor? - Correct Answer The hydrogen-
bond donor is the group that includes both the atom to which the hydrogen atom is
more tightly linked and the hydrogen atom itself, whereas the hydrogen-bond
acceptor is the atom less tightly linked to the hydrogen atom (1008).
Describe the energy and length range of hydrogen bonds. - Correct Answer
Hydrogen bonds are much weaker than covalent bonds. They have energies ranging
from 4 to 20 kJ/mol (from 1 to 5 kcal/mol). Hydrogen bonds are also somewhat
Latest Update
Show a timeline of the Earth showing when oxygen formed, microorganisms,
macroscopic organisms, cells with nuclei, dinosaurs, and human beings formed. -
Correct Answer 1001
How is DNA classified as a chemical? - Correct Answer DNA is a linear polymer
made up of four different types of monomers. It has a fixed backbone from which
protrude variable substituents, referred to as bases (1002).
What is the backbone of DNA made of? - Correct Answer The backbone is built of
repeating sugar-phosphate units. The sugars are molecules of deoxyribose from
which DNA receives its name. Each sugar is connected to two phosphate groups
through different linkages. Moreover, each sugar is oriented in the same way, and so
each DNA strand has directionality, with one end distinguishable from the other.
Joined to each deoxyribose is one of four possible bases: adenine (A), cytosine (C),
guanine (G), and thymine (T). 1002
Draw Adenine bonded to its pair. - Correct Answer 1003
Draw Thymine bonded to its pair. - Correct Answer 1003
Draw Guanine bonded to its pair. - Correct Answer 1004
Draw Cytosine bonded to its pair. - Correct Answer 1004
Describe the key to the functionality of the double helix structure of DNA. - Correct
Answer The key to this structure is that the bases form specific base pairs (bp) held
together by hydrogen bonds: adenine pairs with thymine (A-T) and guanine pairs
with cytosine (G-C). Hydrogen bonds are much weaker than covalent bonds such as
the carbon- carbon or carbon-nitrogen bonds that define the structures of the bases
themselves. Such weak bonds are crucial to biochemical systems; they are weak
enough to be reversibly broken in biochemical processes, yet they are strong
enough, particularly when many form simultaneously, to help stabilize specific
structures such as the double helix.
What enables the copying mechanism of DNA? - Correct Answer Because of base-
pairing, the sequence of bases along one strand completely determines the
sequence along the other strand. As Watson and Crick so coyly wrote: "It has not
escaped our notice that the specific pairing we have postulated immediately
suggests a possible copying mechanism for the genetic material." Thus, if the DNA
, double helix is separated into two single strands, each strand can act as a template
for the generation of its partner strand through specific base-pair formation. 1005
Through what kind of bonding does A connect to T? - Correct Answer 2 hydrogen
bonds
Through what kind of bonding does C connect to G? - Correct Answer 3 hydrogen
bonds
What's the bond length and energy of a C-C bond? - Correct Answer 1.54
Angstroms and bond energy of 355 kJ/mol (85 kcal/mol).
Draw the resonance of adenine. - Correct Answer 1006
How many nm is an angstrom? - Correct Answer an angstrom is 0.1 nm
How does the strength of noncovalent bonds compare to the strength of covalent
bonds? - Correct Answer Noncovalent bonds are weaker than covalent bonds.
What's the energy of an ionic interaction in the form of an equation? - Correct
Answer 1007
An attractive interaction has positive or negative energy? - Correct Answer By
convention, an attractive interaction has a negative energy. The ionic interaction
between two ions bearing single opposite charges separated by 3 Å in water (which
has a dielectric constant of 80) has an energy of -5.8 kJ/mol (-1.4 kcal/mol).
Describe the ionic interaction between two ions bearing single opposite charges in
water and in hexane. - Correct Answer The ionic interaction between two ions
bearing single opposite charges separated by 3 Å in water (which has a dielectric
constant of 80) has an energy of -5.8 kJ/mol (-1.4 kcal/mol). Note how important the
dielectric constant of the medium is. For the same ions separated by 3 Å in a
nonpolar solvent such as hexane (which has a dielectric constant of 2), the energy of
this interaction is -232 kJ/mol (-55 kcal/mol).
How does the dielectric constant of water compare to that of hexane? - Correct
Answer The dielectric constant of water is 40 times greater.
What's the hydrogen-bond donor and acceptor? - Correct Answer The hydrogen-
bond donor is the group that includes both the atom to which the hydrogen atom is
more tightly linked and the hydrogen atom itself, whereas the hydrogen-bond
acceptor is the atom less tightly linked to the hydrogen atom (1008).
Describe the energy and length range of hydrogen bonds. - Correct Answer
Hydrogen bonds are much weaker than covalent bonds. They have energies ranging
from 4 to 20 kJ/mol (from 1 to 5 kcal/mol). Hydrogen bonds are also somewhat
