Smartbook 2-Proteins and Nucleic Acids

How many levels of structure do biologists recognize in proteins?

4

Although scientists generally recognize (blank) levels of protein structure, some proteins lack (blank) structure.

4, quaternary

(Blank) is often referred to as the "energy currency of the cell."

ATP

Typically, fats found in animals (usually solid) are (blank) fats while fats found in plants (usually liquid) are (blank) fats.

Blank 1: saturated Blank 2: unsaturated

The 4 main groups of biological macromolecules are nucleic acids, (blank), (blank), and (blank).

Carbohydrates, proteins, and lipids

(Blank) atoms form the framework of biological molecules.

Carbon

The two main classes of nucleic acids are (blank) and (blank).

DNA and RNA

In cells, the formation of polymers (or polymerization) occurs via chemical reactions termed (blank) reactions. Polymers are broken down (depolymerization) by chemical reactions called (blank) reactions.

Dehydration, hydrolysis

A molecule that only contains (blank) and (blank) is called a hydrocarbon.

Hydrogen and Carbon

Most unsaturated fats come from these organisms:

Plants

Match the level of protein structure with the correct description. Primary, Secondary, Tertiary, Quaternary: a) Sequence of amino acids b) interactions between 2 or more polypeptides to form a protein c) a-helices and B-sheets d) three- dimensional folding of a single polypeptide

Primary a) Sequence of amino acids Secondary c) a-helices and B-sheets Tertiary d) three- dimensional folding of a single polypeptide Quaternary b) interactions between 2 or more polypeptides to form a protein

The structure of proteins is usually discussed in terms of a hierarchy of: a) 4 levels. b) 5 levels. c) 2 levels. d) 3 levels.

a) 4 levels

What are the building blocks of proteins? a) Amino acids b) Carboxylic acids c) Nucleotides

a) Amino acids

The framework or backbone of biological molecules consists predominantly of which of the following atoms? a) Carbon b) Hydrogen c) Oxygen d) Nitrogen

a) Carbon

Select all that apply: What are the three major structural components of an amino acid? a) Carboxyl group b) Amino group c) Glycerol d) Nitrogenous base e) Phosphate group f) Side chain (R)

a) Carboxyl group b) Amino group f) Side chain (R)

Which of the following help proteins fold into their correct 3-D shape? a) Chaperone proteins b) Hormones c) Gene regulators d) Enzymes e) Immunoglobulins

a) Chaperone proteins

Identify the two major classes of nucleic acids. a) DNA and RNA b) Thymine and uracil c) Purines and pyrimidines d) tRNA and mRNA e) Amino acids and fatty acids

a) DNA and RNA

Select all that apply From the following list, choose all lipids. Multiple select question. a) Fats b) Oils c) Certain vitamins d) Polypeptides e) DNA and RNA

a) Fats b) Oils c) Certain vitamins

Which functional group is found in glycerol but not in a fatty acid? a) Hydroxyl b) Methyl c) Carboxyl d) Phosphate e) Amino

a) Hydroxyl

Select all that apply: Choose all the ways in which RNA participates in protein synthesis. a) Some RNA molecules carry amino acids used to synthesize a protein. b) Some RNA molecules are part of the ribosome. c) Some RNA molecules help to fold the protein as it is being made. d) Some RNA molecules can transport newly made proteins to different cell organelles. e) Some RNA molecules carry information for the synthesis of the protein.

a) Some RNA molecules carry amino acids used to synthesize a protein. b) Some RNA molecules are part of the ribosome. e) Some RNA molecules carry information for the synthesis of the protein.

What is the primary structure of a protein? a) The amino acid sequence of the polypeptides. b) The relative frequency of different amino acids in the polypeptides. c) The interactions between amino acids that cause folding of the polypeptides. d) The sequences of secondary structural elements in the polypeptides. e) All secondary folding in the polypeptides caused by interactions between the amino acid side chains.

a) The amino acid sequence of the polypeptides.

Select all that apply: Which of the following are functions of proteins? a) They can store ions, such as calcium and iron. b) They provide structural support for many animal tissues. c) They transport ions and molecules across cell membranes. d) They are the most efficient molecules for storing energy. e) They are the main component of plant cell walls. f) They play a key role in the contraction of muscles.

a) They can store ions, such as calcium and iron. b) They provide structural support for many animal tissues. c) They transport ions and molecules across cell membranes. f) They play a key role in the contraction of muscles.

Select all that apply: Of the following list, choose the functions of proteins in living cells. a) They catalyze chemical reactions. b) They are the immediate source of energy for most cell activities. c) They play a key role in moving materials within cells. d) They transport oxygen in the blood of vertebrates. e) They carry genetic information from one generation to the next. f) They help the body recognize and destroy foreign microbes and cancer cells.

a) They catalyze chemical reactions. c) They play a key role in moving materials within cells. d) They transport oxygen in the blood of vertebrates. f) They help the body recognize and destroy foreign microbes and cancer cells.

Which of the following best describes the behavior of long-chain lipids in water? a) They cluster together in order to minimize contact of their nonpolar regions with the surrounding water. b) They cluster together and expose their nonpolar regions to the surrounding aqueous environment. c) They fold up in order to expose what polar regions they do have to the surrounding aqueous environment. d) They spread apart in order to minimize contact of their nonpolar regions with the surrounding water.

a) They cluster together in order to minimize contact of their nonpolar regions with the surrounding water.

Which of the following statements about phospholipids is true? a) They have a polar "head" and two non-polar "tails". b) They include cholesterol, testosterone, and estrogen. c) They consist of glycerol joined to three fatty acids and a phosphate group.

a) They have a polar "head" and two non-polar "tails".

Select all that apply: Choose all statements that correctly describe phospholipids. a) They have a polar "head" and two nonpolar "tails". b) They often catalyze chemical reactions within cells. c) They spontaneously form micelles or bilayers in water. d) They consist of glycerol joined to two fatty acids and a phosphate group.

a) They have a polar "head" and two nonpolar "tails". c) They spontaneously form micelles or bilayers in water. d) They consist of glycerol joined to two fatty acids and a phosphate group.

Select all that apply: Which describes most animal fats? a) They have only single bonds in their hydrocarbon chains. b) They are unsaturated. c) They have lower melting points than plant fats. d) They are solid at room temperature. e) They are saturated.

a) They have only single bonds in their hydrocarbon chains. d) They are solid at room temperature. e) They are saturated.

Select all that apply Choose all features of fatty acids found in triglycerides. a) They usually have between 14 and 20 carbon atoms. b) They almost always have an odd number of carbon atoms. c) They can have a varying number of double bonds (including none). d) They always contain at least one double bond.

a) They usually have between 14 and 20 carbon atoms. c) They can have a varying number of double bonds (including none).

Select all that apply: Identify functions of ATP. a) To drive energetically unfavorable reactions b) To power the movement of cells c) To store information within the cell d) To accept electrons during oxidation-reduction reactions e) To power transport across cell membranes

a) To drive energetically unfavorable reactions b) To power the movement of cells e) To power transport across cell membranes

How do saturated and unsaturated fats differ in their ability to pack together? a) Unsaturated fats cannot pack as tightly as saturated fats because of the presence of double bonds between the carbon atoms. b) There is no difference in the ability of saturated and unsaturated fats to pack together. c) Saturated fats cannot pack as tightly as unsaturated fats because of the lack of double bonds between the carbon atoms.

a) Unsaturated fats cannot pack as tightly as saturated fats because of the presence of double bonds between the carbon atoms.

Changes in a protein's environment can cause the protein to unfold and lose its shape in a process called a) denaturation. b) hydrolysis. c) depolymerization. d) dissociation.

a) denaturation.

Which of the following are lipids? a) Waxes b) fats c) starch and glycogen d) nucleotides

a) waxes b) fats

Which of the following accurately describes the chemical structure of a typical amino acid found in a protein? a) A central carbon is bound to a carbonyl group, an amino group, and two R groups. b) A central carbon atom is bound to an amino group, carboxyl group, a side chain, and a hydrogen atom. c) A central carbon is double bonded to both an amino group and a carboxyl group.

b) A central carbon atom is bound to an amino group, carboxyl group, a side chain, and a hydrogen atom.

Which of the following bonds is essentially nonpolar? a) C--O b) C--H c) N--H d) C--N e) O--H

b) C--H

If the interactions that maintain the 3-dimensional shape of a protein are disrupted so that the polypeptide chains completely unfold, how is this protein described? a) It is ionized. b) It is denatured. c) It is linearized. d) It is polymerized. e) It is unpolymerized.

b) It is denatured.

Select all that apply Which of the following recently discovered molecules of RNA regulate gene expressions and help protect cells from invading viruses? a) vRNAs b) Micro-RNA c) Small interfering RNAs d) tRNAs

b) Micro-RNA c) Small interfering RNAs

Which of the following molecules have the ability to serve as templates to produce precise copies of themselves? a) Lipids b) Nucleic acids c) Carbohydrates d) Proteins

b) Nucleic acids

Select all that apply: Carbon-oxygen and carbon-nitrogen bonds are described as which of the following? a) Formed by an equal sharing of electrons b) Polar covalent c) Ionic d) Formed by an unequal sharing of electrons e) Nonpolar covalent

b) Polar covalent d) Formed by an unequal sharing of electrons

Select all that apply: Fatty acids can vary in which of the following? a) The number of hydroxyl groups in the hydrocarbon chain b) The length of the hydrocarbon chain c) The number of double bonds in the hydrocarbon chain d) The location of the carboxyl group

b) The length of the hydrocarbon chain c) The number of double bonds in the hydrocarbon chain

Which of the following is a characteristic that all lipids share? a) They contain amino acids. b) They are largely insoluble in water. c) They are largely soluble in water. d) They have a low proportion of nonpolar bonds.

b) They are largely insoluble in water.

Select all that apply: Choose the characteristics that are shared by all lipids? a) They are composed of glycerol and fatty acids. b) They are nonpolar (or mostly nonpolar). c) They are highly soluble in water. d) They are hydrophobic.

b) They are nonpolar (or mostly nonpolar). d) They are hydrophobic.

Select all that apply: Which describes most plant fats? a) They are saturated. b) They are unsaturated. c) They have one or more double bonds between the carbon atoms in their hydrocarbon chains. d) They have higher melting points than most animal fats e) They are liquid at room temperature.

b) They are unsaturated. c) They have one or more double bonds between the carbon atoms in their hydrocarbon chains. e) They are liquid at room temperature.

What is the function of chaperone proteins? a) They transport proteins from one part of the cell to another. b) They help other proteins fold correctly. c) They function as receptors for chemical messengers. d) They transport proteins into and out of the cell. e) They transport nucleic acids into and out of the nucleus.

b) They help other proteins fold correctly.

Select all that apply: Fat molecules are commonly referred to as which of the following? a) Steroids b) Triglycerides c) Triacylglycerols d) Glycerols e) Phospholipids

b) Triglycerides c) Triacylglycerols

Proteins are polymers made up of how many different amino acids? a) 4 b) 5 c) 20 d) 16

c) 20

Select all that apply Lipids are composed mostly of which two elements? Multiple select question. a) Oxygen b) Nitrogen c) Hydrogen d) Phosphorus e) Carbon

c) Hydrogen e) Carbon

What are lipids? a) Lipids are hydrophilic molecules that usually lack nitrogen. b) Lipids are hydrophobic molecules composed primarily of carbon, hydrogen and nitrogen. c) Lipids are hydrophobic molecules composed primarily of hydrogen and carbon. d) Lipids are hydrophilic molecules composed primarily of hydrogen and carbon. e) Lipids are hydrophobic molecules that usually lack oxygen.

c) Lipids are hydrophobic molecules composed primarily of hydrogen and carbon.

Select all that apply: Choose all of the following that accurately describe oils, such as olive oil? a) Oils have high melting points and are solid at room temperature. b) Oils are fats that are high in saturated fatty acids. c) Oils have low melting points and are liquid at room temperature. d) Oils are fats that are high in unsaturated fatty acids.

c) Oils have low melting points and are liquid at room temperature. d) Oils are fats that are high in unsaturated fatty acids.

The sequence of amino acids in a protein is specified by which of the following? a) The overall 3-dimensional shape of the protein b) Special protein-synthsizing enzymes c) The sequence of nucleotides in a segment of DNA d) The alternating sugar-phosphate groups in the DNA backbone

c) The sequence of nucleotides in a segment of DNA

What feature of lipid molecules makes them insoluble in water? a) They are mostly polar. b) They have charged functional groups. c) They are mostly nonpolar. d) They are hydrophilic.

c) They are mostly nonpolar.

How are fat molecules formed? a) Three fatty acids are covalently bound to each other. b) A saturated fatty acid is covalently bound to an unsaturated fatty acid. c) A fatty acid is covalently bound to 3 glycerol molecules. d) Glycerol is covalently bound to three fatty acids.

d) Glycerol is covalently bound to three fatty acids.

Which of the following is an accurate description of a triglyceride? a) Three glycerol molecules joined to one fatty acid b) A hydrocarbon chain bound to 3 carboxyl groups c) A three-carbon chain where each carbon is bound to a hydroxyl group d) One glycerol molecule joined to three fatty acids

d) One glycerol molecule joined to three fatty acids

C--C and C--H bonds are best described as which of the following? a) Ionic b) Moderately polar c) Strongly polar d) Nonpolar

d) nonpolar

If a single protein carries out multiple functions, such as binding DNA and activating transcription, then each function may be carried out by a specific region of the protein called a(n) (blank).

domain

Different regions of a protein that carry out specific functions are referred to as which of the following? a) Amino acids b) Polypeptides c) Subunits d) Tertiary structure e) Domains

e) Domains

Glycerol is a three-carbon polyalcohol consisting of three carbon atoms that each have a(n) (blank) group attached, while a fatty acid consists of a hydrocarbon chain with a(n) (blank) group at one end.

hydroxyl carboxyl

Organisms use sequences of (blank) in their DNA to specify the sequences of (blank) (blank) in their proteins.

nucleotides, amino acids

The amino acid sequence of its polypeptide(s) is called the (blank) structure of a protein.

primary