Chapter 3: End of Chapter Questions
1. What are the major features of a bacterial cell, and how do they fit together for cell
function as a whole?
The bacterial cell has a relatively small genome that is condensed within a region
called the nucleoid. It contains very little, if any, noncoding or extraneous DNA.
The cytoplasm is packed with 70S ribosomes. Depending on the genus, there are
various subcellular components that coordinate cell function. The outer envelope
of the cell consists of the cell membrane, which is surrounded by a cell wall in
most bacteria. Together they protect the cell, regulate exchange with its
surroundings, and are involved in communication with other cells
2. What fundamental traits do most prokaryotes have in common with eukaryotic
microbes? What traits are different?
Overall, they are very similar. The traits stated in question 1 could also be stated
for eukaryotes, except the eukaryotes have more noncoding DNA and the genetic
material is housed in a membrane-bounded nucleus. Whereas the cell membranes
have similar structures and functions, some of their chemical makeup is very
different. Cell walls, if present, are also chemically distinct. Eukaryotes also
contain other organelles, which are membrane-bound, highly specialized entities.
3. Outline the structure of the peptidoglycan sacculus and explain how it expands
during growth. Cite two different kinds of experimental data that support our
current views of the sacculus.
The peptidoglycan sacculus is a single interlinked molecule that encloses the
entire cell. It consists of parallel polymers of disaccharides called glycan chains
cross-linked with peptide side chains. The layers are - alternating units of N-
acetylglucosamine and N-acetylmuramic acid, forming a large sheet. Layers of
these sheets are held together by peptide side chains. Peptide extensions can form
cross-bridges connecting parallel strands of glycans. In essence, the sacculus is a
huge mesh bag, holding the cell together.
Cell wall expansion and septation can be observed by EM and further dissected
by using fluorescence microscopy to follow specific proteins during the growth
and septation process. Genetic mutants have been used in conjunction with
fluorescence microscopy to reveal an even greater understanding of the process.
4. Compare and contrast the structure of Gram-positive and Gram-negative cell
envelopes. Explain the strengths and weaknesses of each kind of envelope.
The Gram-positive cell has only two layers: the cell membrane and the cell wall.
The cell wall contains multiple layers of peptidoglycan. It also contains teichoic
acids, which are not found in Gram-negative cells. Gram-positive cells have much
more structural integrity than Gram-negative cells because of the thick, highly
cross-linked peptidoglycan.
This study source was downloaded by 100000899606396 from CourseHero.com on 10-09-2025 17:26:51 GMT -05:00
https://www.coursehero.com/file/49519408/Chapter-3-end-of-chapter-questionsdocx/
1. What are the major features of a bacterial cell, and how do they fit together for cell
function as a whole?
The bacterial cell has a relatively small genome that is condensed within a region
called the nucleoid. It contains very little, if any, noncoding or extraneous DNA.
The cytoplasm is packed with 70S ribosomes. Depending on the genus, there are
various subcellular components that coordinate cell function. The outer envelope
of the cell consists of the cell membrane, which is surrounded by a cell wall in
most bacteria. Together they protect the cell, regulate exchange with its
surroundings, and are involved in communication with other cells
2. What fundamental traits do most prokaryotes have in common with eukaryotic
microbes? What traits are different?
Overall, they are very similar. The traits stated in question 1 could also be stated
for eukaryotes, except the eukaryotes have more noncoding DNA and the genetic
material is housed in a membrane-bounded nucleus. Whereas the cell membranes
have similar structures and functions, some of their chemical makeup is very
different. Cell walls, if present, are also chemically distinct. Eukaryotes also
contain other organelles, which are membrane-bound, highly specialized entities.
3. Outline the structure of the peptidoglycan sacculus and explain how it expands
during growth. Cite two different kinds of experimental data that support our
current views of the sacculus.
The peptidoglycan sacculus is a single interlinked molecule that encloses the
entire cell. It consists of parallel polymers of disaccharides called glycan chains
cross-linked with peptide side chains. The layers are - alternating units of N-
acetylglucosamine and N-acetylmuramic acid, forming a large sheet. Layers of
these sheets are held together by peptide side chains. Peptide extensions can form
cross-bridges connecting parallel strands of glycans. In essence, the sacculus is a
huge mesh bag, holding the cell together.
Cell wall expansion and septation can be observed by EM and further dissected
by using fluorescence microscopy to follow specific proteins during the growth
and septation process. Genetic mutants have been used in conjunction with
fluorescence microscopy to reveal an even greater understanding of the process.
4. Compare and contrast the structure of Gram-positive and Gram-negative cell
envelopes. Explain the strengths and weaknesses of each kind of envelope.
The Gram-positive cell has only two layers: the cell membrane and the cell wall.
The cell wall contains multiple layers of peptidoglycan. It also contains teichoic
acids, which are not found in Gram-negative cells. Gram-positive cells have much
more structural integrity than Gram-negative cells because of the thick, highly
cross-linked peptidoglycan.
This study source was downloaded by 100000899606396 from CourseHero.com on 10-09-2025 17:26:51 GMT -05:00
https://www.coursehero.com/file/49519408/Chapter-3-end-of-chapter-questionsdocx/
