Exam 2: Chemical Components of Cells

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?

It is now a routine task to determine the exact order in which individual subunits have been linked together in polynucleotides (DNA) and polypeptides (proteins).However, it remains difficult to determine the arrangement of monomers in a polysaccharide.Explain why this is the case.

Which of the following factors DO NOT influence the length of a covalent bond?

Many types of cells have stores of lipids in their cytoplasm, usually seen as fat droplets.What is the lipid most commonly found in these droplets?

Which of the following expressions accurately describes the calculation of pH?

Which combination of answers best completes the following statement: When atoms are held together by __________ __________, they are typically referred to as __________.

Each nucleotide in DNA and RNA has an aromatic base.What is the principal force that keeps the bases in a polymer from interacting with water?

Polar covalent bonds are formed when the electrons in the bond are not shared equally between the two nuclei.Which one of these molecules contains polar bonds?

Silicon is an element that, like carbon, has four vacancies in its outer electron shell and therefore has the same bonding chemistry as carbon.Silicon is not found to any significant degree in the molecules found in living systems, however.Does this difference arise because elemental carbon is more abundant than silicon? What other explanations are there for the preferential selection of carbon over silicon as the basis for the molecules of life?

For each of the following sentences, fill in the blanks with the best word or phrase selected from the list below.Not all words or phrases will be used; each word or phrase should be used only once. amino ionized polypeptides \alpha -carbon length protein carbon noncovalent R group carboxyl peptide bonds side chains hydroxide Proteins are __________ built from amino acids, which each have an amino group and a __________ group attached to the central __________.There are 20 possible __________ that differ in structure and are generally referred to as "R." In solutions of neutral pH, amino acids are __________, carrying both a positive and a negative charge.When a protein is made, amino acids are linked together through __________, which are formed by condensation reactions between the carboxyl end of the last amino acid and the __________ end of the next amino acid to be added to the growing chain.

A.If 0.5 mole of glucose weighs 90 g, what is the molecular mass of glucose? B.How much glucose do you have to add to water to produce 1 liter of a 0.25 M solution of glucose? C.How many molecules are there in 1 mole of glucose?

There is incredible chemical diversity even in the simplest of cells.A typical bacterial cell contains more than 6000 different types of molecules.From the list below, select the class of molecules with the largest number of different types.

Figure 2-34 -Oligosaccharides are short sugar polymers that can become covalently linked to proteins and lipids through condensation reactions.These modified proteins and lipids are called glycoproteins and glycolipids, respectively.Within a protein, which of the amino acids (shown in Figure 2-34) is the most probable target for this type of modification?

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

A.What is the pH of pure water? B.What concentration of hydronium ions does a solution of pH₈ contain? C.Complete the following reaction: CH₃COOH + H₂O ↔ __________. D.Will the reaction in (C) occur more readily (be driven to the right) if the pH of the solution is high?

Which subatomic particles can vary between isotopes of the same element, without changing the observed chemical properties?

The first task you are assigned in your summer laboratory job is to prepare a concentrated NaOH stock solution.The molecular weight of NaOH is 40.How many grams of solid NaOH will you need to weigh out to obtain a 500 mL solution that has a concentration of 10 M?

As a protein is made, the polypeptide is in an extended conformation, with every amino acid exposed to the aqueous environment.Although both polar and charged side chains can mix readily with water, this is not the case for nonpolar side chains.Explain how hydrophobic interactions may play a role in the early stages of protein folding, and have an influence on the final protein conformation.