CHEM 11 Spring 2015 Practice Exam 3

Questions and Answers

A hemiacetal contains?

Two OR groups (alkoxy groups)

Two OR groups (alkoxy groups) bonded to the same carbon

An OH (hydroxyl) group and an OR (alkoxy) group

An OH (hydroxyl) group and an OR (alkoxy) group bonded to the same carbon (correct)

The functional group R C O H is characteristic of?

Esters

Carboxylic acids

Ethers

Ketones

Aldehydes (correct)

The functional group R C O R' is characteristic of?

Ethers

Esters (correct)

Ketones

Aldehydes

Carboxylic acids

Which compound has the lowest boiling point?

CH3CH2CON(CH2CH3)2 Signup and view all the answers

Heating a carboxylic acid with a primary amine forms _____ + water.

a primary amide Signup and view all the answers

Which name is possible for a carboxylic acid?

m-butylbenzoic acid Signup and view all the answers

What is the IUPAC name for the substance having the following condensed structural formula? (CH3)3CCH2COOH

3,3-dimethylbutanoic acid Signup and view all the answers

Which compound has the highest boiling point?

CH3CH2CH2CH2CH2COOH Signup and view all the answers

What products are produced when a carboxylic acid reacts with an alcohol, in the presence of sulfuric acid?

an ester + water Signup and view all the answers

Carboxylic acids react with bases, such as NaOH, to form _____.

water-soluble salts Signup and view all the answers

What is the treatment of a carboxylic acid (RCOOH) with an alcohol (R'OH) in the presence of an acid catalyst to form an ester (RCOOR') called?

a Fischer esterification Signup and view all the answers

What products are formed in the acid hydrolysis of?

ethanol and acetic acid Signup and view all the answers

Which compound is the most soluble in water?

CH3CH2CH2CH2CH2COOK Signup and view all the answers

Which of these structures represents a soap?

CH3(CH2)14CO2– Na+ Signup and view all the answers

What is the IUPAC name of the compound shown here?

N-propylhexanamine Signup and view all the answers

What is the IUPAC name of the compound shown here?

N-butyl-4-heptanamine Signup and view all the answers

Which compound has the lowest boiling point?

(CH3)2NCH2CH2CH2CH2CH3 Signup and view all the answers

What is the IUPAC name of the compound shown here?

N-ethyl-N-methylpropanammonium chloride Signup and view all the answers

Which substance is a weak acid in aqueous solution?

CH3COOH Signup and view all the answers

Which substance is a weak base in aqueous solution?

CH3NH2 Signup and view all the answers

What are monosaccharides with a carbonyl group at C1 called?

aldoses Signup and view all the answers

What is the classification of the compound shown here?

a ketotetrose Signup and view all the answers

Which compound is the most soluble in water?

CHOCHOHCHOHCHOHCHOHCH2OH Signup and view all the answers

When converting a Fischer projection to a Haworth projection, where are all of the substituents on the right side of the carbon skeleton drawn in the Haworth projection?

down Signup and view all the answers

Which is not an example of a lipid?

phenol Signup and view all the answers

What functional group is contained in most hydrolyzable lipids?

ester Signup and view all the answers

Linolenic acid, CH3CH2CH=CHCH2CH=CHCH2CH2CH2CH2CH2CH2CH2COOH, is _____.

an omega-3 acid Signup and view all the answers

Which compound is most likely to be an oil at the lowest temperature?

CH3(CH2)2CH=CH(CH2)2CH=CH(CH2)2CH=CH(CH2)2COOH Signup and view all the answers

What two types of compounds react to form a wax?

a fatty acid and a high molecular weight alcohol Signup and view all the answers

What process uses integral proteins to move ions, specifically Na+, K+, and Ca2+, through a cell membrane, traveling against the concentration gradient from the side of lower concentration to the side of higher concentration?

active transport Signup and view all the answers

What is the main component of the cell membrane?

phospholipids Signup and view all the answers

Which type of linkage between the two rings is in the structure shown?

12-β-glycoside linkage Signup and view all the answers

What is the structure of amylopectin?

Branched skeleton of glucose molecules joined by 14-α-glycoside linkages Signup and view all the answers

What type of polysaccharide is depicted in the 'cartoon' shown?

amylose Signup and view all the answers

Which is the simplest amino acid?

glycine Signup and view all the answers

Which amino acid is an acidic amino acid?

aspartic acid Signup and view all the answers

What is the charge on alanine at a pH equal to the pI?

neutral Signup and view all the answers

The term protein is usually reserved for polymers of more than _____ amino acids.

100 Signup and view all the answers

How many different dipeptides can be formed when one valine reacts with one glycine?

2 Signup and view all the answers

What is the N-terminal amino acid in the tetrapeptide glycylalanylisoleucylmethionine?

glycine Signup and view all the answers

What is the strongest type of interaction between two cysteine amino acids in a protein?

disulfide bond Signup and view all the answers

What is the strongest type of interaction between an isoleucine amino acid and a phenylalanine amino acid in a protein?

London dispersion forces Signup and view all the answers

What is the process of altering the shape of a protein without breaking the amide bonds that form the primary structure?

denaturation Signup and view all the answers

From the name alone, which compound is an enzyme?

triosephosphate isomerase Signup and view all the answers

What is the three-dimensional arrangement of localized regions of a protein into α-helices and β-pleated sheets called?

the secondary structure of a protein Signup and view all the answers

Which is not a characteristic of an α-helix?

The R groups of the amino acids extend inward from the core of the helix. Signup and view all the answers

Which amino acid is most likely to be located in the interior of a globular protein?

leucine Signup and view all the answers

Which is an example of a globular protein?

hemoglobin Signup and view all the answers

What type of inhibitor binds to the enzyme but does not bind at the active site?

a noncompetitive inhibitor Signup and view all the answers

Which component is not part of a nucleotide?

an amino acid Signup and view all the answers

Which base is found in DNA or RNA, but not both?

uracil Signup and view all the answers

What is a nucleoside?

a monosaccharide + a base Signup and view all the answers

A polynucleotide contains _____

one free phosphate group at the 5' end Signup and view all the answers

How many hydrogen bonds form between a G–C base pair in a DNA double helix?

3 Signup and view all the answers

What is the complementary strand for the DNA strand 5'–AAGGTAGC–3'?

3'–TTCCATCG–5' Signup and view all the answers

What is the process by which DNA makes a copy of itself when a cell divides?

replication Signup and view all the answers

What is the step in the synthesis of proteins from RNA called where the genetic message contained in RNA determines the specific amino acid sequence of a protein?

translation Signup and view all the answers

Which is not a type of RNA molecule?

dRNA Signup and view all the answers

Which statement is not true?

Three codons are called start codons. Signup and view all the answers

Which is not one of the three stages in translation?

mutation Signup and view all the answers

What is the amino acid sequence that is coded by mRNA sequence 5' AAG GCU AGU GGC 3'?

Lys–Ala–Ser–Gly Signup and view all the answers

Which codon does not code for alanine?

GAC Signup and view all the answers

Each individual tRNA contains _____

an anticodon of three nucleotides that is complementary to the codon in mRNA and identifies individual amino acids. Signup and view all the answers

What polypeptide would be synthesized from the following template strand of DNA: 3' CGG AGA CGG ACG 5'?

Arg–Arg–Arg–Cys Signup and view all the answers

What type of mutation is expressed when a DNA sequence changes from GGA TCA CCG GAA… to GGA TCC CGG…?

a point mutation Signup and view all the answers

A DNA sequence segment is initially AAA ATG TGA CCC. Which mutation would have the largest effect on the resultant protein synthesized?

AAA ATG GAC CCU Signup and view all the answers

Study Notes

Hemiacetals and Acetals

Hemiacetal consists of a hydroxyl (OH) group and an alkoxy (OR) group on the same carbon atom.
An acetal is formed when two alkoxy groups are bound to the same carbon atom.

Functional Groups

Aldehydes are characterized by the R-C(=O)-H functional group.
Ketones have the R-C(=O)-R' functional group.
Carboxylic acids contain a carboxyl group, while esters are related to carboxylic acids with an alkoxy group.

Boiling Points

Boiling points of compounds can vary significantly based on molecular structure and functional groups, with amines and carboxylic acids generally exhibiting higher boiling points.

Amides and Esters

Heating a carboxylic acid with a primary amine produces a primary amide and water.
Carboxylic acids react with alcohols in the presence of acid to form esters, a process known as Fischer esterification.

Solubility and Salts

The presence of long-chain hydrocarbons affects the solubility of compounds in water, with shorter chains and polar functional groups generally increasing solubility.

Lipids and Fatty Acids

Natural lipids often contain ester functional groups and may include triacylglycerols and cholesterol.
Linolenic acid is classified as an omega-3 fatty acid due to its structure.

Proteins and Amino Acids

The simplest amino acid is glycine.
Cysteine can form disulfide bonds, which are strong interactions in proteins, while isoleucine and phenylalanine are linked by weaker London dispersion forces.

Nucleotides and Nucleic Acids

A nucleotide consists of a nitrogen base, a monosaccharide, and a phosphate group.
The base uracil is unique to RNA, while thymine is found only in DNA.

Translation and Codons

Translation synthesizes proteins based on mRNA sequences, with specific codons coding for particular amino acids.
Each tRNA carries an anticodon that recognizes its complementary mRNA codon during protein synthesis.

Mutations

Mutations can affect protein synthesis, with point mutations being a single base change that can alter codons.
The impact of mutations varies, with insertions and deletions often causing significant changes in protein structure.

General Concepts

Lipids generally form through the reaction of fatty acids with high molecular weight alcohols to create waxes.
Integral proteins play a crucial role in transporting ions across cell membranes via active transport.

Molecular Structures

Understanding molecular structures and drawings is crucial for identifying compounds such as soaps, amino acids, and sugars.
Distinction between globular and fibrous proteins is important in biochemistry, with hemoglobin being a key example of a globular protein.

Functional Classification

Primary, secondary, and tertiary structures of proteins define their function and stability.
The classification of saccharides includes categories like aldoses and ketoses, which depend on the position of the carbonyl group.

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Description

Test your knowledge of hemiacetals and related compounds in this practice exam for CHEM 11. The quiz includes questions on structural characteristics and functional groups, focusing on important organic chemistry concepts. Prepare ahead for your upcoming exams with these essential practice questions.