Bio I - Exam 2 - Chapter 5

A nucleotide is made of which of the following chemical components?

A nitrogenous base, a phosphate group, and a pentose sugar.

What do Alzheimer's, Parkinson's, and mad cow disease have in common?

All have been associated with the buildup of misfolded proteins in cells.

Enzyme molecules require a specific shape to perform their catalytic function. Which of the following might alter the shape of an enzymatic protein?

All of the listed responses are correct.

Which of the following is true regarding complementary base pairing in DNA and RNA molecules?

Although the base pairing between two strands of DNA in a DNA molecule can be thousands to millions of base pairs long, base pairing in an RNA molecule is limited to short stretches of nucleotides in the same molecule or between two RNA molecules.

Which of the following molecules is a monosaccharide?

C6H12O6

Which of the following is a polymer?

Cellulose, a plant cell wall component

Which type of protein shields a newly forming protein from cytoplasmic influences while it is folding into its functional form?

Chaperonins

A shortage of phosphorus in the soil would make it especially difficult for a plant to manufacture __________.

DNA

What is the process by which monomers are linked together to form polymers?

Dehydration or condensation reactions

When a protein is denatured, why does it lose its functionality?

Denaturation breaks the weak bonds, such as hydrogen bonds and van der Waals interactions, that hold the protein in its three-dimensional shape. Without the proper shape, the protein cannot function.

Which is the term for compounds that do not mix with water?

Hydrophobic

What is a distinguishing feature of most naturally occurring fats?

Nearly all naturally occurring unsaturated fats have cis double bonds.

What is a key feature of omega-3 fatty acids that distinguishes them from other types of fatty acids?

None of the listed responses correctly describes a distinguishing key feature of omega-3 fatty acids.

To what does the term "polypeptide" refer?

None of the listed responses is correct.

The alpha helix and beta pleated sheet represent which level of protein structure?

Secondary structure

Amylase is an enzyme that breaks down starch. Why can't the same enzyme break down cellulose?

The monosaccharide monomers in cellulose are bonded together differently than in starch.

Which of the following are pyrimidines found in the nucleic acid DNA?

Thymine and cytosine

The peptide bond is __________.

a covalent bond joining amino acids together to form a polypeptide

A glucose molecule is to starch as __________.

a nucleotide is to a nucleic acid

In a hydrolysis reaction, __________, and in this process water is __________.

a polymer is broken up into its constituent monomers; consumed

Manufacturers make vegetable oils solid or semisolid at room temperature by __________.

adding hydrogen atoms to the double bonds in the fatty acid hydrocarbon chains

On the basis of the principle of complementary base pairing, you would expect the percentage of __________ to be equal to the percentage of __________.

adenine; thymine

Protein molecules are polymers (chains) of __________.

amino acid molecules

Lipids differ from other large biological molecules in that they __________.

are not truly polymers

Which of the following components of a tossed salad will pass through the human digestive tract and be digested the least?

cellulose (in the lettuce)

At a conference, the speaker's grand finale was sautéing mealworms (insect larvae) in butter and serving them to the audience. They were crunchy (like popcorn hulls) because their exoskeletons contain the polysaccharide __________.

chitin

The type of bond that forms to join monomers (such as sugars and amino acids) into polymers (such as starch and proteins) is a(n) __________ bond.

covalent

Carbohydrates are used in our bodies mainly for __________.

energy storage and release

Some lipids are formed when fatty acids are linked to glycerol. These subunits are linked together by __________.

ester linkages

Which of the following carbohydrate molecules has the lowest molecular weight?

glucose

A polysaccharide that is used for storing energy in human muscle and liver cells is __________.

glycogen

The subunits (monomers) in cellulose are linked together by __________.

glycosidic linkages

The fatty acid tails of a phospholipid are __________ because they __________.

hydrophobic; have no charges to which water molecules can adhere

The sex hormones estrogen, progesterone, and testosterone belong to which class of molecules?

lipids

Which of the following is the major energy storage compound of plant seeds?

oils

In what polysaccharide form do plants store glucose to be available later as an energy source?

starch

The polysaccharide that you are most likely to have eaten recently is __________.

starch

The overall three-dimensional shape of a single polypeptide is called the __________.

tertiary structure

In a 1-4 glycosidic linkage, __________.

the number 1 carbon in one monosaccharide is bound to the number 4 carbon in another monosaccharide

The "primary structure" of a protein refers to __________.

the sequence of amino acids

One characteristic shared by sucrose, lactose, and maltose is that __________.

they are all disaccharides

Carbohydrates can function in which of the following ways?

Structural support and energy storage

High cholesterol levels are considered a major risk factor for heart disease. If it is so bad for humans, why does the body make cholesterol in the first place?

Cholesterol is the basis for many important molecules such as sex hormones.

Generally, animals cannot digest (hydrolyze) the glycosidic linkages between the glucose molecules in cellulose. How then do cows get enough nutrients from eating grass?

Microorganisms in their digestive tracts hydrolyze the cellulose to individual glucose units.

Nutritionally, saturated triacylglycerols are considered to be less healthful than unsaturated triacylglycerols. What is the difference between them?

Saturated triacylglycerols have more hydrogen atoms than unsaturated triacylglycerols.

Which of the following is a true statement comparing phospholipids and triacylglycerols (fats and oils)?

Phospholipid molecules have a distinctly polar "head" and a distinctly nonpolar "tail," whereas triacylglycerols are predominantly nonpolar.

Which of the following describes a difference between DNA and RNA?

RNA molecules consist of a single polynucleotide chain, whereas DNA molecules consist of two polynucleotide chains organized into a double helix; one of their nitrogenous bases is different; and they contain different sugars

If a small droplet of triacylglycerol molecules is suspended in water, the fat molecules form a "ball of spaghetti" with no particular orientation. But if a droplet of phospholipid molecules is put in water, all the molecules point outward, toward the water. Phospholipids are forced into this orientation because phospholipids have __________.

a charged end and a noncharged end

The lipids that form the main structural component of cell membranes are __________.

phospholipids

Cellulose is a __________ made of many __________.

polymer; glucose molecules