MB CH3: Macromolecules & Enzymes PART 2

The reaction that joins two monomers to form a polymer is known as a _____ reaction. The molecule of water formed is due to the interaction between _____ and a hydrogen ion.

dehydration ... a hydroxyl group The reaction removes a molecule of water, so it dehydrates the molecule. The interaction occurs between the hydroxyl group of one molecule and a hydrogen ion of a second molecule.

A DNA nucleotide is composed of a __________.

deoxyribose sugar, which is bonded to a phosphate group and a nitrogenous base The deoxyribose sugar is attached to both the phosphate group and the nitrogenous base. Return to Assignment

What is the correct label for "A"? THIS IS AN IMAGE

energy of activation The energy of activation must be overcome in order for a reaction to proceed.

An enzyme _____.

is an organic catalyst

As a result of its involvement in a reaction, an enzyme _____.

is unchanged

Most enzymes are _____.

proteins

Enzymes work by _____.

reducing activation energy

What name is given to the reactants in an enzymatically catalyzed reaction?

substrate

When two monosaccharides link to form a disaccharide, the by-product is __________.

water Two monosaccharides are linked via a dehydration reaction, and water is produced in the process.

Biological Macromolecules PART A Can you match the terms to their definitions? Drag the terms on the left to the appropriate blanks on the right to complete the sentences.

1. A *DEHYDRATION* reaction builds polymers from monomers. 2. A *HYDROLYSIS* reaction breaks down polymers into monomers. 3. A(n) *AMINO ACID* is a building block of polypeptides, such as the protein hemoglobin. 4. A(n) *POLYPEPTIDE* is a polymer of amino acids. 5. A(n) *MONOSACCHARIDE* is a building block of polysaccharides such as starch. 6. A(n) *POLYSACCHARIDE* is a polymer of monosaccharides. 7. A(n) *NUCLEOTIDE* is a building block of polynucleotides such as DNA. 8. A(n) *POLYNUCLEOTIDE* is a polymer of nucleotides.

Biological Macromolecules PART B Each of the main types of biological macromolecules (proteins, nucleic acids, carbohydrates, and lipids) are polymers of specific types of monomers. Match the monomers with their polymer examples. The monomers may be used more than once.

1. Myoglobin is a protein that binds oxygen molecules and is a polymer of *AMINO ACIDS.* 2. Insulin is a protein hormone that regulates blood glucose levels and is a polymer of *AMINO ACIDS*. 3. Animals store energy in the form of glycogen, a carbohydrate made up of thousands of *MONOSACCHARIDES.* 4. The nucleic acids DNA and RNA carry genetic information and are made up of many *NUCLEOTIDES.*

Biological Macromolecules PART C Which of the following is an example of a dehydration reaction?

DNA molecules are replicated in a cell by building new DNA molecules from nucleotides. Deyhdration reactions are used to make larger molecules (polymers) from smaller molecules (monomers). Bulding a new DNA molecule (a polynucleotide) from nucleotides (monomers) is an example of a dehydration reaction. The other options describe hydrolysis reactions.

Which statement regarding enzyme function is true?

Excessive salt ions can cause an enzyme to denature. Few enzymes can tolerate extremely salty conditions, because the salt ions interfere with some of the chemical bonds that maintain protein structure.

Use the graph and your knowledge of enzymes to identify the THREE true statements about enzymes.

Statement 1: By binding to reactant molecules, enzymes make it easier for the bonds in the molecules to break apart. Statement 2: Reactants cannot convert to products without an initial input of energy to start the reaction. Statement 3: Enzymes lower the overall energy input needed for a reaction to occur. For a chemical reaction to begin, chemical bonds in the reactant molecules must be broken. This process requires that the molecules absorb energy from their surroundings. The energy that must be invested to start a reaction is called activation energy because it activates the reactants and triggers the chemical reaction. Enzymes enable metabolism to occur by reducing the amount of activation energy required to break the bonds of reactant molecules.

Biological Macromolecules PART D Once you eat a cookie, enzymes in your digestive tract begin to break down the cookie into smaller molecules. Which TWO statements are true regarding this process?

Statement 1: Hydrolysis reactions are breaking the macromolecules in the cookie down into smaller molecules Statement 2: Water is required for the reactions that break the macromolecules in the cookie down into smaller molecules. Enzymes that break down food into smaller molecules are performing hydrolysis reactions, which require water.

Which of these statements about enzyme inhibitors is true?

The action of competitive inhibitors may be reversible or irreversible. Competitive inhibitors that bind covalently to the enzyme would be irreversible, and those that bind weakly would be reversible.

A glucose molecule is to starch as __________.

a nucleotide is to a nucleic acid Nucleotides are the monomers that make nucleic acids, just as glucose is the monosaccharide from which starch is constructed.

Which curve shows the course of the reaction in the presence of an enzyme--the black curve or the red curve? Which line represents the activation energy for that reaction--a, b, or c? THIS IS AN IMAGE

red curve; line b

Which of the following would be affected when a protein is denatured?

tertiary structure The tertiary and secondary structures are a product of localized hydrogen bonding. The hydrogen bond is relatively weak and easily disrupted.