Some proteins have alpha helices, some have beta sheets, and still others have a combination of both. What makes it possible for proteins to have these common structural elements?

Which of the following is NOT a feature of α helices?

Which of the following statements is TRUE?

Chemical reactions carried out by living systems depend on the ability of some organisms to capture and use atoms from nonliving sources in the environment. The specific subset of these reactions that break down nutrients in food can be described as

The best way to know if an organic molecule has been reduced is to see if there was an increase in the number of _________ bonds.

ΔG° indicates the change in the standard free energy as a reactant is converted to product. Given what you know about these values, which reaction below is the most favorable?

ΔG measures the change of free energy in a system as it converts reactant (Y) into product (X). When [Y] = [X], ΔG is equal to

What does the K_m value indicate with respect to enzyme–substrate interactions?

The study of enzymes also includes an examination of how the activity is regulated. Molecules that can act as competitive inhibitors for a specific reaction are often similar in shape and size to the enzyme’s substrate. Which variable or variables used to describe enzyme activity will remain the same in the presence and absence of a competitive inhibitor?

Energy cannot be created or destroyed, but it can be converted into other types of energy. Cells harvest some of the potential energy in the chemical bonds of foodstuffs to generate stored chemical energy in the form of activated carrier molecules, which are often employed to join two molecules together in ________ reactions.

You have a concentrated stock solution of 10 M NaOH and want to use it to produce a 150 mL solution of 3 M NaOH. What volume of water and stock solutions will you measure out to make this new solution?

An ionic bond between two atoms is formed as a result of the

Although covalent bonds are 10–100 times stronger than noncovalent interactions, many biological processes depend upon the number and type of noncovalent interactions between molecules. Which of the noncovalent interactions below will contribute most to the strong and specific binding of two molecules, such as a pair of proteins?

Which of the following monomer building blocks is necessary to assemble selectively permeable boundaries around and inside cells?

What is the pH of 100mM solution of HCl (strong acid)? pH=-log[H]

Which chemical group is present in the N terminus of proteins?

Which of the following is NOT TRUE about amino acids (find all that are false):

In the case of a simple conversion reaction such as X→Y, which value of ΔG° is associated with a larger concentration of X than Y at equilibrium?

Which of the following IS NOT a tenet of cell theory:

What type of regulation is it when a product inhibits its own synthesis?

The formation of CO2 from CH4 occurs by which type of reaction?

What defines the atomic number of an atom?

The terms “prokaryote” and “bacterium” are synonyms.

How do you like this 213 class so far? (no matter which answer you choose, you get the points!)

The amino acids glutamine and glutamic acid differ only in the structure of part of their side chains. At pH7, what type of interactions are possible for glutamic acid but not for glutamine?

Which of the following is FALSE about molecular chaperones?

The Ras protein is a GTPase that functions in many growth factor–signaling pathways. In its active form, with GTP bound, it transmits a downstream signal that leads to cell proliferation; in its inactive form, with GDP bound, the signal is not transmitted. Mutations in the gene for Ras are found in many cancers. Of the choices below, which alteration of Ras activity is most likely to contribute to the uncontrolled growth of cancer cells?

Cholesterol is an essential component of biological membranes. Although it is much smaller than the typical phospholipids and glycolipids in the membrane, it is a/an _________ molecule, having both hydrophilic and hydrophobic regions.

Cells require one particular monosaccharide as a starting material to synthesize nucleotide building blocks. Which of the monosaccharides below fills this important role?

Both DNA and RNA are synthesized by covalently linking a nucleoside triphosphate to the previous nucleotide, constantly adding to a growing chain. In the case of DNA, the new strand becomes part of a stable helix. The two strands are complementary in sequence and antiparallel in directionality. What is the principal force that holds these two strands together?

Because there are four different monomer building blocks that can be used to assemble RNA polymers, the number of possible sequence combinations that can be created for an RNA molecule made of 100 nucleotides is

Macromolecules in the cell can often interact transiently as a result of noncovalent interactions. These weak interactions also produce stable, highly specific interactions between molecules. Which of the factors below is the most significant in determining whether the interaction will be transient or stable?

Polypeptides are synthesized from amino acid building blocks. The condensation reaction between the growing polypeptide chain and the next amino acid to be added involves the loss of

Which of the following is NOT a feature commonly observed in β sheets?

Two or three α helices can sometimes wrap around each other to form coiled-coils. The stable wrapping of one helix around another is typically driven by ________ interactions.

Which of these amino acids is not charged but polar.

Enzymes cannot change the equilibrium of biochemical reactions

__________ play an important role in organizing lipid molecules with long hydrocarbon tails into biological membranes.