Microbiology

Nina Parker

Chapter 7

Microbial Biochemistry - all with Video Answers

Educators

Chapter Questions

Problem 1

Which of these elements is not a micronutrient?
a. $\mathrm{C}$
b. $\mathrm{Ca}$
c. $\mathrm{Co}$
d. $\mathrm{Cu}$

Emily Marty

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Problem 2

Which of the following is the name for molecules whose structures are nonsuperimposable mirror images?
a. structural isomers
b. monomers
c. polymers
d. enantiomers

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Problem 3

By definition, carbohydrates contain which elements?
a. carbon and hydrogen
b. carbon, hydrogen, and nitrogen
c. carbon, hydrogen, and oxygen
d. carbon and oxygen

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Problem 4

Monosaccharides may link together to form polysaccharides by forming which type of bond?
a. hydrogen
b. peptide
c. ionic
d. glycosidic

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Problem 5

Which of the following describes lipids?
a. a source of nutrients for organisms
b. energy-storage molecules
c. molecules having structural role in membranes
d. molecules that are part of hormones and pigments
e. all of the above

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Problem 6

Molecules bearing both polar and nonpolar groups are said to be which of the following?
a. hydrophilic
b. amphipathic
c. hydrophobic
d. polyfunctional

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Problem 7

Which of the following groups varies among different amino acids?
a. hydrogen atom
b. carboxyl group
c. $R$ group
d. amino group

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Problem 8

The amino acids present in proteins differ in which of the following?
a. size
b. shape
c. side groups
d. all of the above

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Problem 9

Which of the following bonds are not involved in tertiary structure?
a. peptide bonds
b. ionic bonds
c. hydrophobic interactions
d. hydrogen bonds

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Problem 10

Which of the following characteristics/compounds is not considered to be a phenotypic biochemical characteristic used of microbial identification?
a. poly-\beta-hydroxybutyrate
b. small-subunit (16S) rRNA gene
c. carbon utilization
d. lipid composition

Joanna Quigley

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Problem 11

Proteomic analysis is a methodology that deals with which of the following?
a. the analysis of proteins functioning as enzymes within the cell
b. analysis of transport proteins in the cell
c. the analysis of integral proteins of the cell membrane
d. the study of all accumulated proteins of an organism

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Problem 12

Which method involves the generation of gas phase ions from intact microorganisms?
a. FAME
b. PLFA
c. MALDI-TOF
d. Lancefield group testing

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Problem 13

Which method involves the analysis of membranebound carbohydrates?
a. FAME
b. PLFA
c. MALDI-TOF
d. Lancefield group testing

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Problem 14

Which method involves conversion of a microbe's lipids to volatile compounds for analysis by gas chromatography?
a. FAME
b. proteomic analysis
c. MALDI-TOF
d. Lancefield group testing

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Problem 15

True/False
Aldehydes, amides, carboxylic acids, esters, and ketones all contain carbonyl groups.

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Problem 16

True/False
Two molecules containing the same types and numbers of atoms but different bonding sequences are called enantiomers.

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Problem 17

True/False
Lipids are a naturally occurring group of substances that are not soluble in water but are freely soluble in organic solvents.

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Problem 18

True/False
Fatty acids having no double bonds are called "unsaturated."

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Problem 19

True/False
A triglyceride is formed by joining three glycerol molecules to a fatty acid backbone in a dehydration reaction.

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Problem 20

True/False
A change in one amino acid in a protein sequence always results in a loss of function.

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Problem 21

True/False
MALDI-TOF relies on obtaining a unique mass spectrum for the bacteria tested and then checking the acquired mass spectrum against the spectrum databases registered in the analysis software to identify the microorganism.

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Problem 22

True/False
Lancefield group tests can identify microbes using antibodies that specifically bind cell-surface proteins.

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Problem 23

Match each polysaccharide with its description.
___chitin A. energy storage polymer in plants
___glycogen B. structural polymer found in plants
___starch C. structural polymer found in cell walls of fungi and exoskeletons of some animals
___cellulose D. energy storage polymer found in animal cells and bacteria

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Problem 24

Waxes contain esters formed from long-chain __________ and saturated __________, and they may also contain substituted hydrocarbons.

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Problem 25

Cholesterol is the most common member of the __________ group, found in animal tissues; it has a tetracyclic carbon ring system with a __________ bond in one of the rings and one free __________group.

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Problem 26

The sequence of amino acids in a protein is called its __________.

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Problem 27

Denaturation implies the loss of the __________ and __________ structures without the loss of the __________ structure.

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Problem 28

A FAME analysis involves the conversion of _______ to more volatile _____ for analysis using ____________.

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Problem 29

Why are carbon, nitrogen, oxygen, and hydrogen the most abundant elements in living matter and, therefore, considered macronutrients?

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Problem 30

Identify the functional group in each of the depicted structural formulas.

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Problem 31

What are monosaccharides, disaccharides, and polysaccharides?

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Problem 32

Describe the structure of a typical phospholipid. Are these molecules polar or nonpolar?

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Problem 33

Compare MALDI-TOF, FAME, and PLFA, and explain how each technique would be used to identify pathogens.

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Problem 34

The structural formula shown corresponds to penicillin $G$, a narrow-spectrum antibiotic that is given intravenously or intramuscularly as a treatment for several bacterial diseases. The antibiotic is produced by fungi of the genus Penicillium. (a) Identify three major functional groups in this molecule that each comprise two simpler functional groups. (b) Name the two simpler functional groups composing each of the major functional groups identified in (a).

Joanna Quigley

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Problem 35

The figure depicts the structural formulas of glucose, galactose, and fructose.
(a) Circle the functional groups that classify the sugars either an aldose or a ketose, and identify each sugar as one or the other. (b) The chemical formula of these compounds is the same, although the structural formula is different. What are such compounds called?

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Problem 36

Structural diagrams for the linear and cyclic forms of a monosaccharide are shown. (a) What is the molecular formula for this monosaccharide? (Count the C, $\mathrm{H}$ and $\mathrm{O}$ atoms in each to confirm that these two molecules have the same formula, and report this formula.) (b) Identify which hydroxyl group in the linear structure undergoes the ring-forming reaction with the carbonyl group.

Alexander Cheng

Alexander Cheng

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Problem 37

The term "dextrose" is commonly used in medical settings when referring to the biologically relevant isomer of the monosaccharide glucose. Explain the logic of this alternative name.

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Problem 38

Microorganisms can thrive under many different conditions, including high-temperature environments such as hot springs. To function properly, cell membranes have to be in a fluid state. How do you expect the fatty acid content (saturated versus unsaturated) of bacteria living in high-temperature environments might compare with that of bacteria living in more moderate temperatures?

Emily Marty

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Problem 39

Heating a protein sufficiently may cause it to denature. Considering the definition of denaturation, what does this statement say about the strengths of peptide bonds in comparison to hydrogen bonds?

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Problem 40

The image shown represents a tetrapeptide.
(a) How many peptide bonds are in this molecule?
(b) Identify the side groups of the four amino acids composing this peptide.

Joanna Quigley

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