BSC 3096 Chapter 2

A 1.0 M NaCl solution contains 58.5 g of salt per liter. (a) How many molecules of NaCl are present in 1 L of this solution? (b) How many millimoles of NaCl are present? (c) How many equivalents of Na+ are present? (d) Express 58.5 g of NaCl per liter as a percent solution.

(a) 6.02×1023 molecules of NaCl, (b) 1000 millimoles, (c) 1 equivalent, (d) 5.85% solution

What is the pH of a 0.005 M HCl solution? Assume complete dissociation. A. 0.30 B. 3.3 C. 2.3 D. 4.3

2.3

A change in pH value of one unit indicates a A. change of 10-2 in pH. B. change of 10-1 in pH. C. 1-fold change in [H+]. D. 10 fold change in [H+]. E. Cannot be determined.

10 fold change in [H+]

How would you make 200 mL of a 10% glucose solution? Calculate the molarity of this solution. How many millimoles of glucose are present in 500 mL of this solution? (Hint: What is the molecular mass of glucose?)

10 g/100 mL=100 g/L×1 mole/180 g=0.556 moles/L or 556 millimoles/L (556 mM). 500 mL of 10% glucose would have 50 g glucose×1 mole/180 g = 278 millimoles glucose.

If in an acid-base reaction H2SO42- donates two H+, one mole of H2SO42- would equal how many equivalents? A. 4 B. 2 C. 1 D. 0.5 E. 0.75

2

100 mg/dL is a typical blood concentration of glucose. The molecular weight of glucose is approximately 180 daltons. What is the molarity of this solution in millimoles? A. 18 B. 10 C. 0.56 D. 5.6 E. 100

5.6

How many grams of NaCl, m.w. 58.5 daltons, are necessary to make 1 liter of 5% saline? A. 1 B. 58.5 C. 2.9 D. 50 E. 6.02 × 1023

50

A 5 M solution of 100 mL of glucose contains how many grams of glucose, m.w. 180 daltons? A. 180 B. 90 C. 1.0 D. 360 E. 6.02 × 1023

90

Which of the following would be considered an allosteric modulator? A. A substance that can be displaced by competition at the active site. B. A substance that binds irreversibly. C. A substance that binds to proteins away from the active site. D. A substance that has no effect on the affinity of the ligand. E. A substance involved in activation via phosphorylation.

A substance that binds to proteins away from the active site.

Name three nucleotides or nucleic acids, and tell why each one is important.

ATP: usable energy in a high-energy bond. DNA stores genetic information. RNA translates genetic information into proteins. cAMP: transfer of signals into cells. NAD and FAD transfer energy.

The most important energy-transferring compound in cells is a nucleotide known as A. protein. B. fructose. C. deoxyribonucleic acid. D.glucose. E. adenosine triphosphate

Adenosine triphosphate

Drug B should mimic the activity of a normal nervous system signal molecule.

Agonist

A modulator that increases protein function by binding to a protein distant from the binding site is called __________. A. allosteric activator B. allosteric inhibitor C. a cofactor D. a competitive inhibitor

Allosteric activator

A negatively charged ion is called a(n) , and a positively charged ion is called a(n) .

Anion, cation

The organic molecules known as phospholipids are key components of cell membranes and composed of which molecules? A. nucleotides B. glycerol C. fatty acids D. amino acids E. both glycerol and fatty acids

Both glycerol and fatty acids

A molecule that moderates changes in pH is called a .

Buffer

Which compound is hydrophobic? A. Table salt B. Potassium ions (K+) C. Sugar D. Butter

Butter

Essential amino acids that are used to build proteins A. can be derived from the foods we eat and digest. B. can only be made by cells within our bodies. C. can be used medically for both diagnosis and treatment of diseases. D. exist in twenty six different configurations. E. Are linked together by ionic chemical bonds in proteins.

Can be derived from the foods we eats and digest.

Which of the following biological molecules does glycogen belong to? A. carbohydrates B. lipids C. nucleotides D. proteins

Carbohydrates

A positively charged ion is called a(n) A. proton. B. neutron. C. electron. D. anion. E. cation.

Cation

An ion, such as Ca2+ or Mg2+, that must be present in order for an enzyme to work is called a(n) .

Cofactor

If a reaction which is stopped by substance X can recover when a lot more of the native activator is supplied, substance X would be considered which of the following? A. a phosphotase B. covalent modulator C. competitive inhibitor D. allosteric modulator E. irreversible antagonist

Competitive inhibitor

In a(n) __________bond, electrons are shared between atoms. If the electrons are attracted more strongly to one atom than to the other, the molecule is said to be a(n)____ molecule. If the electrons are evenly shared, the molecule is said to be a(n)______molecule.

Covalent, polar, nonpolar

Based on what you know from experience about the tendency of the following substances to dissolve in water, predict whether they are polar or nonpolar molecules: table sugar, vegetable oil.

Table sugar dissolves easily, so it is polar. Vegetable oil does not dissolve in water, so it is nonpolar.

Calculate the amount of NaCl you would weigh out to make one liter of 0.9% NaCl. Explain how you would make a liter of this solution

Dissolve 9 g of NaCl in water

True or false? All organic molecules are biomolecules.

False. All biomolecules are organic molecules, but the reverse is not true.

The storage form of glucose for animals is called ______. starch chitin glucose lactose glycogen

Glycogen

All of these statements about carbohydrates are true except one. Identify the exception. A. Simple sugars include galactose, glucose, and ribose. B. Polysaccharides are important both for energy storage and to provide structure to cells. C. Cellulose is the most abundant carbohydrate on earth. D. Glycogen is important both for energy storage and to provide structure for cells. E. Glycogen is a storage polysaccharide made by animal cells.

Glycogen is important both for energy storage and to provide structure for cells.

In the equation H2CO3 ↔ H+ + HCO3- which of these chemical speices is an acid? HCO3- H+ H2CO3

H2CO3

A component of an important buffer in the human body is A. HCO3-. B. HCl. C. H2O. D. H+. E. NaCl.

HCO3-

Potassium ions (K+) are: A. Hydrophilic and do not dissolve in water. B. Hydrophobic and do not dissolve in water. C. Hydrophobic and dissolve in water. D. Hydrophilic and dissolve in water.

Hydrophilic and dissolve in water

You know that two soluble proteins are isoforms of each other. What can you predict about their structures, functions, and affinities for ligands?

Isoforms are structurally similar, with similar functions but differing affinities for ligands. They may function best under different conditions.

A molecule that binds to another molecule is called a(n) .

Ligand

A(n) ________ is any molecule or ion that binds to another molecule. A. cofactor B. phospholipid C. vitamin D. enzyme E. ligand

Ligand

To which of the following groups of biomolecules do triglycerides and steroids belong? A. nucleotides B. lipids and proteins C. proteins D. lipids E. Carbohydrates

Lipids

Proteins combined with fats are called , and proteins combined with carbohydrates are called .

Lipoproteins, glycoproteins

When atoms bind tightly to one another, such as H2O or O2, one unit is called a(n) .

Molecule

The harder a cell works, the more CO2 it produces. CO2 is carried in the blood according to the following equation: CO2+H2O ⇌ H++HCO −3 What effect does hard work by your muscle cells have on the pH of the blood?

More CO2 means more H+by the law of mass action. More H+ means a decrease in pH.

Part complete Nucleic acids are polymers of units called A. bases. B. fatty acids. C. ribose. D. nucleotides. E. amino acids.

Nucleotides

An atom of carbon has four unpaired electrons in an outer shell with space for eight electrons. How many covalent bonds will one carbon atom form with other atoms?

One carbon atom needs to share four electrons to fill its outer shell; therefore, it will form four covalent bonds.

Name two elements whose presence contributes to a molecule becoming a polar molecule.

Oxygen and nitrogen strongly attract electrons and tend to form polar bonds.

Define the pH of a solution. If pH is less than 7, the solution is ; if pH is greater than 7, the solution is .

PH= [H+] Acidic, basic

A solution in which [H+]=10−3 M is (acidic/basic), whereas a solution in which [H+]=10−10 M is (acidic/basic). Give the pH for each of these solutions.p

Ph= 3 acidic pH=10 basic

List the four kinds of biomolecules. Give an example of each kind that is relevant to physiology.

Proteins (collagen, hemoglobin, enzymes); carbohydrates (glucose, sucrose); lipids (cholesterol, phospholipids); and nucleic acids (ATP, DNA, RNA).

Glycoproteins are made up of proteins and lipids. lipids and carbohydrates. proteins and carbohydrates. lipids and nucleotides.

Proteins and lipids.

Which of the following biological molecules exhibit the characteristics of saturation, specificity and competition? A. lipids B. carbohydrates C. lipids and proteins D. receptor proteins E. nucleotides

Receptor proteins

Proteins that bind signal molecules and initiate cellular responses are called __________. A. enzymes B. binding proteins C. immunoglobulins D. receptors

Receptors

Which is most likely to be solid at room temperature? polyunsaturated fats monounsaturated fats saturated fats

Saturated fats

The concentration of a solution expresses the amount of A. solute per volume of solution. B. solvent per volume of solute. C. solvent per volume of solution. D. solute per volume of solvent. E. None of the answers are correct.

Solute per volume of solution.

The largest carbohydrate molecules are called polysaccharides because they are composed of ________ molecules bonded together with one another. pyrimidine purine sugar amino acid nucleotide

Sugar

When an enzyme reaches its saturation point, A. the binding sites are fully occupied, and the reaction rate reaches a minimal value. B. the binding sites are fully occupied, and the reaction rate reaches a maximum value. C. the binding sites are minimally occupied, and the reaction rate reaches a maximum value. D. the binding sites are minimally occupied, and the reaction rate reaches a minimal valu

The binding sites are fully occupied, and the reaction rate reaches a maximum value.

During intense exercise our muscles produce lactic acid. This weak acid partially dissociates in water, forming the anion lactate and H+. What do you predict should happen to the pH of the cytoplasm inside of muscle cells during intense exercise? A. The intracellullar pH of muscles cells should decrease. B. The intracellullar pH of muscles cells should not change. C. The intracellullar pH of muscles cells should increase.

The intracellullar pH of muscles cells should decrease.

Which of the following would cause a protein response rate to be maximal? A. The protein has been down-regulated. B. The protein is denatured. C. The protein binding sites are saturated. D. There are too few ligand molecules.

The proteins binding sites are saturated.

Which of the following is an important characteristic of lipids? A. They are nonpolar. B. They are converted to hormones. C. They dissolve in water. D. They can be linked into long chains

They are nonpolar.

Why do nonpolar molecules, such as cholesterol, repel water? A. The covalent bonds of lipids create a small charge that repels water molecules. B. They contain many hydrogen bonds. C. They have an even distribution of electrons. D. Their electrons tend to cluster around the carbon atoms within the molecule.

They have an even distribution of electrons.

Glycerol plus three fatty acids produces a ______. triglyceride eicosaniod steriod phospholipid

Triglyceride

Drug A must bind to an enzyme and enhance its activity.

allosteric activator covalent modulator

Drug C should block the activity of a membrane receptor protein.

antagonist competitive inhibitor

Which of the following formulas describes the relationship between pH and hydrogen ions? A. [H+] = log pH B. pH = log [H+] C. pH= [H+] + [OH-] D. pH = -log [H+] E. [H+] = -log pH

pH = -log [H+]

Induced fit

the ability of a protein to alter shape as it binds a ligand

Specificty

the ability of a protein to bind one molecule but not another

When an enzyme reaches its saturation point, A. the amount of substrate for the enzyme to act upon is very high. B. the amount of product produced by the enzyme decreases. C. the amount of substrate for the enzyme to act upon is very low. D. the amount of product produced continues to increase. E. the amount of substrate for the enzyme to act upon is very low and the amount of product produced by the enzyme decreases.

the amount of substrate for the enzyme to act upon is very high.

binding site

the part of a protein molecule that binds the ligand

In a 5% NaCl solution, A. the solute is water. B. this means there are 5 grams of sodium chloride for every 100 mL of total solution. C. this means there are 5 grams of sodium chloride for every 100 mL of water and there are 5 grams of sodium chloride for every 100 mL of total solution. D. this means there are 5 grams of sodium chloride for every 100 mL of water. E. this means there are 5 grams of sodium chloride for every 100 mL of total solution and the solute is water.

this means there are 5 grams of sodium chloride for every 100 mL of total solution.