High School Biology : Understanding Proteins and Nucleic Acids

Study concepts, example questions & explanations for High School Biology

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Example Questions

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Example Question #1 : Understanding Proteins And Nucleic Acids

Which macromolecule is polymerized using peptide bonds?

Possible Answers:

Proteins

Lipids

Polysaccharides

Nucleic acids

Correct answer:

Proteins

Explanation:

Proteins are composed of amino acids linked together by peptide bonds. Nucleic acids are linked by phosphodiester bonds and polysaccharides are held together by glycosidic linkages. Lipid polymers are linked by simple covalent bonds.

Example Question #2 : Understanding Proteins And Nucleic Acids

Which of the following base pairs would never be seen in a healthy double helix of a nucleic acid?

Possible Answers:

Adenine-thymine

Adenine-uracil

Guanine-cytosine

Guanine-uracil

Correct answer:

Guanine-uracil

Explanation:

In DNA, guanine will always pair with cytosine (C-G) and adenine will always pair with thymine (A-T). In RNA, thymine is replaced with the pyrimidine uracil, meaning that adenine will pair with uracil in RNA (A-U). Guanine and uracil will never be paired together.

Example Question #3 : Understanding Proteins And Nucleic Acids

Which of the following can be found in proteins?

Possible Answers:

Ribonucleotides

Phosphates

Nucleosomes

Nucleotides

Amino acids

Correct answer:

Amino acids

Explanation:

Proteins are made up of a string of amino acids. Ribosomes are responsible for facilitating the formation of covalent peptide bonds between amino acids to build the polypeptide chain. Proteins called chaperones then help fold the protein into the proper shape.

Nucleotides are found in DNA and ribonucleotides are found in RNA. Nucleosomes are small regions of DNA that are tightly wound around histone proteins. Phosphates are functional groups made of one phosphorus atom and four oxygen atoms. Phosphates are found in numerous molecules, including DNA, RNA, and phospholipids in the cell membrane, but are not generally found in proteins.

 

Example Question #4 : Understanding Proteins And Nucleic Acids

A membrane pump transports ions against their concentration gradient. The pump most likely uses what type of cellular energy source?

Possible Answers:

Nucleotide derivative

Lipid

Polypeptide

Carbohydrate

Correct answer:

Nucleotide derivative

Explanation:

The question states that the pump transports ions against their concentration gradient. This means that this pump must use active transport. Recall that active transport requires energy in the form of ATP. ATP, or adenine triphosphate, is a type of nucleotide because it contains a nitrogenous base, a pentose sugar, and phosphate groups.

Lipids and carbohydrates (such as glucose) are the energy source for the body; however, these macromolecules themselves do not provide energy for cellular processes. They undergo metabolism and generate ATP, the molecule used by cellular processes that require energy.

Example Question #5 : Understanding Proteins And Nucleic Acids

In which level of protein structure are the  helices and  pleated sheets found?

Possible Answers:

Quaternary

Principle

Secondary

Primary

Tertiary

Correct answer:

Secondary

Explanation:

Primary protein structure is the sequence of the amino acids, linked by peptide bonds. Secondary protein structure involves  helices and  pleated sheets formed by hydrogen bonds between backbone amino and carboxyl groups. Tertiary protein structure involves electrostatic interactions between the R groups of the amino acids in the polypeptide. The tertiary structure of a protein may be globular or filamentous, and may include disulfide bonds and/or salt bridges. Quaternary protein structure involves interactions between two or more polypeptide chains.

Example Question #6 : Understanding Proteins And Nucleic Acids

Enzymes belong to which macromolecule-building block pair?

Possible Answers:

Polypeptide; carbohydrate

Polypeptide; protein

Nucleotides; nucleic acids

Polypeptide; lipid

Polysaccharide; protein 

Correct answer:

Polypeptide; protein

Explanation:

Enzymes are polypeptides. Polypeptides are created from proteins/amino acids. They contain a nitrogen, and have a nitrogen-carbon-carbon  backbone.  

Carbohydrates are referred to as polysaccharides when they form large molecules. They function as energy storage, and are responsible for the structure of plant cell walls. They are made of carbon, hydrogen, and oxygen.

Lipids in large molecules make up fats, oils, waxes, and phospholipids. They provide membrane structure, energy storage, and insulation. They are also made of carbon, hydrogen, and oxygen, and contain numerous carbon-hydrogen bonds. 

Nucleic acids (DNA and RNA) are made of chains of nucleotides, bound together by phosphodiester bonds.

Example Question #7 : Understanding Proteins And Nucleic Acids

Which of the following is responsible for the unique chemical and physical properties of different amino acids?

Possible Answers:

Amino end

Carboxyl end

C-terminus

N-terminus

Side chains

Correct answer:

Side chains

Explanation:

All amino acids have a carboxyl end, and an amino end, both of which contain the same respective atoms. The main differences in amino acids come from the different side chains contained by each amino acid.

Example Question #8 : Understanding Proteins And Nucleic Acids

The __________ group is exposed at the N terminus end of a protein, while the __________ group is exposed at the C terminus. 

Possible Answers:

nitrogen. . . carbonyl

nitrogen. . . carboxylic acid

amine. . . carboxylic acid

amino. . . carbonyl

Correct answer:

amine. . . carboxylic acid

Explanation:

The N terminus is the end of the protein with the amino group——exposed, and the C terminus is the end of the protein with the carboxyl group——exposed. 

Example Question #9 : Understanding Proteins And Nucleic Acids

Which of the following is not a function of a protein?

Possible Answers:

Storage

Transport

Memory

Structure

Correct answer:

Memory

Explanation:

Proteins have six main functions: 1) movement (e.g. actin and myosin), 2) structure (e.g. keratin), 3) transport (e.g. hemoglobin), 4) protection (e.g. antibodies), 5) communication (e.g. hormones), 6) and catalyzation of chemical reactions (e.g. enzymes).

Example Question #10 : Understanding Proteins And Nucleic Acids

Which of the following does not contribute to amino acid structure? 

Possible Answers:

Amino group

Alpha carbon

Carboxyl group 

Glycerol 

R-side group

Correct answer:

Glycerol 

Explanation:

The structure of a given amino acid consists of an alpha carbon, amino group, carboxyl group, hydrogen, and a R-side group. R-side groups can have a variety of characteristics. They can be non-polar, polar, acidic, or basic. Amino acids can bond together through a peptide bond via dehydration synthesis—the loss of a single oxygen from one amino acid’s carboxyl group and two hydrogens from the other amino acid’s amine group.

Polypeptides are polymers of amino acids formed by this process. Glycerol is a component of a phospholipid.

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