Chapter 5 - biology

The flow of genetic information in a cell goes from _____.

DNA to RNA to protein

What structural difference accounts for the functional differences between starch and cellulose?

Starch and cellulose differ in the glycosidic linkages between their glucose monomers.

What role does complementary base pairing play in nucleic acids?

The complementary base pairing of the two strands of DNA makes possible the precise replication of DNA every time a cell divides, ensuring that genetic information is faithfully transmitted. In some types of RNA, complementary base pairing enables RNA molecules to assume specific three-dimensional shapes that facilitate diverse functions.

Which feature of large biological molecules explains their great diversity?

The many ways that monomers of each class of biological molecule can be combined into polymers

What is the fundamental basis for the differences between large carbohydrates, proteins, and nucleic acids?

The polymers of large carbohydrates (polysaccharides), proteins, and nucleic acids are built from three different types of monomers (monosaccharides, amino acids, and nucleotides, respectively).

How many hydrogen atoms can be attached to carbon B?

1

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 or polar end and an uncharged or nonpolar end

Which of the following is not analogous to a biological polymer?

a truck

which functional group can act as a base?

amino

Olestra is a calorie-free fat that is synthesized by reacting sucrose with fatty acids. What is the maximum number of fatty acid molecules that can crosslink with the sucrose molecule?

8

Explain the basis for the great diversity of proteins.

A polypeptide, which may consist of hundreds of amino acids in a specific sequence (primary structure),has regions of coils and pleats (secondary structure), which are then folded into irregular contortions (tertiary structure) and may be non covalently associated with other polypeptides (quaternary structure). The linear order of amino acids, with the varying properties of their side chains (R groups), determines what secondary and tertiary structures will form to produce a protein.The resulting unique three-dimensional shapes of proteins are key to their specific and diverse functions.

Compare starch and cellulose. What role does each play in the human body?

Both starch and cellulose are polymers of glucose, but the glucose monomers are in the αα configuration in starch and the ββ configuration in cellulose. The glycosidic linkages thus have different geometries, giving the polymers different shapes and thus different properties. Starch is an energy-storage compound in plants; cellulose is a structural component of plant cell walls. Humans can hydrolyze starch to provide energy but cannot hydrolyze cellulose. Cellulose aids in the passage of food through the digestive tract.

Which of the following molecules is a monosaccharide?

C6H12O6

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)

Why are lipids not considered to be polymers or macromolecules?

Lipids are not polymers because they do not exist as a chain of linked monomers. They are not considered macromolecules because they do not reach the giant size of many polysaccharides, proteins, and nucleic acids.

Which of the following lists ranks these molecules in the correct order by size from smallest to largest?

Water, glucose, sucrose, protein

Given the sequences of a particular gene in fruit flies, fish, mice, and humans, predict the relative similarity of the human sequence to that of each of the other species.

You would expect the human gene sequence to be most similar to that of the mouse (another mammal), then to that of the fish (another vertebrate), and least similar to that of the fruit fly (an invertebrate).

People who are lactose intolerant cannot extract energy from milk because ________.

an enzyme is not functioning correctly

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

are not truly polymers

Which of the following categories includes all others in the list?

carbohydrate

Which functional group can act as an acid?

carboxyl

Plant cell walls consist mainly of __________.

cellulose

Which polysaccharide is an important component in the structure of many animal and fungal cells?

chitin

Palm coconut oils are more like animal fats than other plant oils. Because they __________ than other plant oils, they may contribute to cardiovascular disease.

contain fewer double bonds

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

glycogen

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are in the αα form. Which of the following could amylase break down?

glycogen, starch, and amylopectin

Sucrose is formed when glucose is joined to fructose by a(n) _____.

glycosidic linkage

The characteristic that all lipids have in common is __________.

none of them dissolve in water

The building blocks or monomers of nucleic acid molecules are called_____.

nucleotides

A hydrophobic amino acid R group (side group) would be found where in a properly folded protein?

on the inside of the folded chain, away from water

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

phospholipids

The structural level of a protein least affected by a disruption in hydrogen bonding is the______.

primary level

The four main categories of large biological molecules present in living systems are __________.

proteins, nucleic acids, carbohydrates, and lipids

Some regions of a polypeptide may coil or fold back on themselves. This folding is called __________, and the coils or folds are held in place by __________.

secondary structure,..... hydrogen bonds

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

they are all disaccharides

Which of the following statements is correct regarding starch and cellulose?

they are polymers of glucose

A dehydration reaction (or condensation reaction) is the process in which __________.

water molecules are produced as a polymer is formed from monomers

Maltose is a disaccharide that can easily be digested into glucose molecules. Which type of glycosidic linkage connects glucose molecules in maltose?

α 1-4