NAS2 Part 6 Review

What are biological macromolecules?

Large organic molecules necessary for life that are built from smaller organic molecules.

What are the four major classes of biological macromolecules?

Carbohydrates, lipids, proteins, and nucleic acids.

Which molecules make up most of a cell’s dry mass?

Biological macromolecules. Water makes up most of the cell’s total or complete mass.

True or false: Water makes up most of a cell’s dry mass.

False. Macromolecules make up most of a cell’s dry mass; water makes up most of its complete mass.

What does it mean that biological macromolecules are organic?

They contain carbon bonded to hydrogen.

Besides carbon and hydrogen, which elements may occur in biological macromolecules?

Oxygen, nitrogen, and additional minor elements.

What is a monomer?

A single subunit or building block that can join with other subunits to form a larger molecule.

What is a polymer?

A larger molecule formed when monomers join together through covalent bonds.

How do monomers and polymers differ?

A monomer is a single building block; a polymer is a larger molecule made from repeating or joined monomers.

What type of bond joins monomers into polymers?

A covalent bond.

Why can one kind of monomer produce several different polymers?

The same monomer can be linked in different arrangements and configurations.

Which three polymers are composed of glucose monomers?

Starch, glycogen, and cellulose.

True or false: Different polymers must always be made from different monomers.

False. The same kind of monomer can be arranged in different ways to form different polymers.

How does variation in monomer type and arrangement contribute to biological diversity?

Different monomers can combine in many configurations, producing a diverse range of macromolecules with different properties.

What is dehydration synthesis?

A reaction that joins monomers while releasing a water molecule; it is also called a condensation reaction.

What does the phrase “dehydration synthesis” mean literally?

To put together while losing water.

What are two names for the reaction that joins monomers and releases water?

Dehydration synthesis and condensation reaction.

Which groups combine to produce water during dehydration synthesis?

A hydrogen from one monomer combines with a hydroxyl group from another monomer.

Sequence the main events of dehydration synthesis.

Two monomers align; an H from one and an OH from the other form water; water is released; the monomers share electrons and form a covalent bond.

Is water a reactant or a product in dehydration synthesis?

A product.

What happens as additional monomers join during dehydration synthesis?

A chain of repeating monomers grows, forming a polymer.

Why does dehydration synthesis generally require energy?

It forms new covalent bonds, and new bond formation requires an energy investment.

True or false: Dehydration synthesis breaks covalent bonds and adds water.

False. Dehydration synthesis forms covalent bonds and releases water.

In Figure 3.2, which two monomers join during dehydration synthesis?

Two glucose molecules.

What disaccharide is formed in Figure 3.2?

Maltose.

What additional product is formed when two glucose molecules form maltose in Figure 3.2?

One water molecule.

In a diagram of two glucose molecules becoming maltose plus H2O, which process is shown?

Dehydration synthesis (condensation).

If three monomers are joined into one chain by dehydration synthesis, how many water molecules are released?

Two water molecules, because two covalent linkages must form.

If five monomers are assembled into one unbranched polymer, how many dehydration reactions are required?

Four dehydration reactions, one for each bond joining adjacent monomers.

What is hydrolysis?

A reaction that breaks a polymer into smaller units or monomers by adding water across a covalent bond.

Is water a reactant or a product in hydrolysis?

A reactant.

What happens to a water molecule during hydrolysis?

It splits; one product receives a hydrogen and the other receives a hydroxyl group.

Sequence the main events of hydrolysis.

Water is added across a covalent bond; the bond breaks; water splits; one component gains H and the other gains OH.

What generally happens to energy during hydrolysis?

Energy is generally released as bonds are broken.

True or false: Hydrolysis removes water to build polymers.

False. Hydrolysis adds water to break polymers into smaller units.

In Figure 3.3, what molecule is broken down by hydrolysis?

Maltose.

What products form when maltose undergoes hydrolysis in Figure 3.3?

Two glucose monomers.

What role does water play in Figure 3.3?

Water is added as a reactant and split so that H and OH attach to the two glucose products.

In a diagram of maltose plus H2O becoming two glucose molecules, which process is shown?

Hydrolysis.

How are dehydration synthesis and hydrolysis related?

They are reverse reactions: dehydration builds larger molecules by releasing water, while hydrolysis breaks them down by adding water.

Compare the bond changes in dehydration synthesis and hydrolysis.

Dehydration synthesis forms new covalent bonds; hydrolysis breaks covalent bonds.

Compare water’s role in dehydration synthesis and hydrolysis.

Dehydration synthesis produces water; hydrolysis consumes water.

Compare the typical energy changes of dehydration synthesis and hydrolysis.

Dehydration synthesis generally requires energy; hydrolysis generally releases energy.

A reaction produces water and creates a covalent bond between subunits. Is it hydrolysis or dehydration synthesis?

Dehydration synthesis.

A reaction uses water and separates a molecule into two components. Is it hydrolysis or dehydration synthesis?

Hydrolysis.

A polymer is split at three covalent linkages. How many water molecules are required?

Three water molecules, one for each bond hydrolyzed.

What is the role of enzymes in dehydration and hydrolysis reactions?

Specific enzymes catalyze, or speed up, the reactions.

Are the same enzymes used for every macromolecule reaction?

No. Each monomer–polymer reaction is specific to its macromolecule class and requires specific enzymes.

Why is hydrolysis important in digestion?

It breaks food macromolecules into smaller molecules that intestinal cells can absorb more easily.

What do digested macromolecules ultimately provide for cells?

Smaller molecules that can provide energy for cellular activities.

Which enzymes named in Section 3.1 break down carbohydrates?

Amylase, sucrase, lactase, and maltase.

Which enzyme breaks down starch and other carbohydrate substrates in digestion?

Amylase.

Which enzyme breaks down sucrose?

Sucrase.

Which enzyme breaks down lactose?

Lactase.

Which enzyme breaks down maltose?

Maltase.

What are proteases?

Enzymes that break down proteins.

Which specific protein-digesting enzymes are named in Section 3.1?

Pepsin and peptidase.

What non-enzyme substance named in the section helps break down proteins?

Hydrochloric acid.

Which enzymes break down lipids?

Lipases.

A person cannot efficiently digest lactose. Which enzyme is most directly deficient?

Lactase.

Which enzyme would most directly hydrolyze the maltose shown in Figure 3.3 during digestion?

Maltase.

Which general enzyme class would hydrolyze dietary proteins?

Proteases.

Which enzyme class would hydrolyze dietary fats?

Lipases.

What additional property can a polymer acquire compared with its separate monomers?

A polymer can have new characteristics that are not simply the sum of the properties of its individual monomers.

Why does assembling many monomers into polymers help maintain cellular osmotic conditions?

A polymer produces much lower osmotic pressure than the same ingredients present as many separate small molecules.

True or false: A polymer creates the same osmotic pressure as all of its monomers remaining separate.

False. The polymer creates much lower osmotic pressure, which helps maintain cellular osmotic conditions.

Why is storing small molecules as polymers advantageous beyond compact organization?

It reduces the number of separate dissolved particles and therefore lowers osmotic pressure inside the cell.

Summarize macromolecule synthesis in one statement.

Monomers are joined by enzyme-catalyzed dehydration reactions that form covalent bonds, release water, require energy, and build polymers.

Summarize macromolecule breakdown in one statement.

Polymers are separated by enzyme-catalyzed hydrolysis reactions that add water across covalent bonds, produce smaller units, and generally release energy.

Complete the pattern: dehydration synthesis—builds, releases water, forms bonds; hydrolysis—____.

Breaks down, uses water, and breaks bonds.

A digestive enzyme converts a disaccharide into two monosaccharides. Identify the reaction type and water’s role.

The reaction is hydrolysis, and water is consumed and split across the bond.

True or false: Hydrolysis and dehydration reactions operate identically for every macromolecule because all use the same monomers and enzymes.

False. Their general patterns are similar across macromolecules, but each monomer–polymer reaction is specific to its class and uses specific enzymes.