Microbiology: Chapter

Peptidoglycans are composed of sugars and ________.

Amino acids The glycan refers to the sugars, and peptide refers to the other component Amino acids combine to form the peptide portion of the peptidoglycan

The filament and basal body are associated with which of the following external structures found in some bacterial cells?

Flagella

A bacterial cell possesses a glycocalyx. Which of the following is false? - It will be engulfed more quickly by defensive cells of the host - It will be less likely to dry out - It will be able to attach to surfaces - It will be more pathogenic

It will be engulfed more quickly by defensive cells of the host

Gram-negative bacterial cell wall

Lipopolysaccharides Dual lipid bilayer membrane Thin layer of peptidoglycan Periplasmic space

One of the ways smooth endoplasmic reticulum (ER) differs from rough endoplasmic reticulum is that rough ER is covered by

Ribosomes Ribosomes dock on the rough ER, and proteins are completed inside the rough ER

What structure acts as a selective barrier, regulating the traffic of materials into and out of the cell?

Plasma membrane The plasma membrane surrounds the cell and regulates the movement of materials into and out of the cell

Peptidoglycan is a polymer of millions of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) sugars based on glucose molecules linked together in long chains cross-braced with four amino acids that link individual polymer chains together in a chain-link fence pattern. Layers of cross-braced NAG and NAM sheets are stacked vertically and held together by proteins with lipid anchors attached to the cell's cytoplasmic membrane to form a scaffold of sugars and proteins that is able to hold the bacterial cell's shape, even in response to extreme osmotic pressures. How would you expect a microbiology student to be able to describe the composition of peptidoglycan? What is the composition of the peptidoglycan layers found in the cell wall of bacteria?

Short amino acid chains, NAG, NAM, and some lipid proteins

Where is the genetic information of the cell stored?

Nucleus DNA is the genetic information of the cell and it is stored in the nucleus

One chain of alternating NAGs and NAMs is connected to another chain via _____.

Tetrapeptides Tetrapeptides are composed of four amino acids and make up the "peptido" portion of peptidoglycan

Which of the following organelles breaks down worn-out organelles? - Rough endoplasmic reticulum (ER) - Mitochondria - Smooth endoplasmic reticulum (ER) - Golgi apparatus - Lysosomes

Lysosomes Lysosomes contain digestive enzymes and break down worn-out organelles

Where in a cell is ATP made?

Mitochondria ATP is made in mitochondria

What carries instructions for making proteins from the nucleus into the cytoplasm

mRNA The "m" in mRNA stands for "messenger"; mRNA is the messenger that carries genetic instructions from the nucleus to the cytoplasm

Gram-positive bacterial cell wall

Teichoic acids Single lipid bilayer membrane Thick layer of peptidoglycan

Which of the following is NOT a characteristic of eukaryotic cell? - Presence of a nuclear envelope - Contain chromosomes composed of DNA and histones - Presence of membrane-bound organelles - Can undergo transcription and translation simultaneously

Can undergo transcription and translation simultaneously

The structural framework in a cell is the

Cytoskeleton The cytoskeleton is the structural framework of a cell

A cell wall is a requirement for all living bacteria

False

At this point in writing your tutorial, you have to find a way to get across to the students the importance of a cell wall to a bacterium. How do you convey that the bacterial cell will be at the mercy of its environment? The cell wall will need to act as a support mechanism to neutralize the inflow or outflow of water that would alter the shape of the cell. The cell cannot search out for a better place in the environment that has more available water; or if there is water that it has a high enough solute concentration that the cell will not gain water. Because that's the problem for a bacterial cell, it cannot control the tonicity due to solute concentrations in the surrounding water. Water will flow in or out depending on solute concentrations and the only thing a bacterial cell can do to keep from collapsing due to water loss or rupturing due to too much water coming in is to have a strong cell wall that will hold its shape regardless of the osmotic pressures. The rigidity of the cell wall will maintain a set shape regardless of water flow. The proteins and lipids that anchor the cytoplasmic membrane to the cell wall will tether the membrane to the peptidoglycan layer so that when environmental conditions result in the loss of water from the cell, the membrane will not collapse in on itself. Similarly, changes in environmental conditions that would result in the inflow of water would expand the volume of the cell to the limits of the cell wall and no more. The composition of the cell wall allows for the expansion and contraction of the cell wall in response to the gain or loss of water from the cell.

False Since the bacterial cell is at the mercy of the environment, it requires a rigid structure to maintain its shape when osmotic pressure would cause a cell to shrink or expand. The cell wall The cell wall peptidoglycan layer is flexible but still rigid enough to maintain its shape; the cytoplasmic membrane is attached to the cell wall through the use of proteins and lipids

With the description of the different cell walls, membranes, and associated proteins set in the students' minds, you now need to introduce them to the idea that the cell wall can also act as a foundation to build things upon. Bacterial appendages require a strong foundation that will offer the support needed to move and function in a dynamic world. For example, flagella are long, whiplike protein structures that are used by many Gram-positive and Gram-negative bacteria for locomotion. In order to function effectively, a flagellum must be firmly anchored to the cell wall. How will you be able to get across the idea that the peptidoglycan cell wall is strong enough to support such a mechanism? With a protein rod that passes through the cell wall and protein rings used to anchor it in the membranes, these basal bodies are the rudimentary biological motors that use ATP power to spin the hook and the flagella attached to it. Bacterial flagella have a biological motor that spins within the cell wall and is powered by ATP. This allows the flagella to spin in a whiplike motion to propel the bacterium.

False The biological motor that spins the flagella for bacterial propulsion is powered by the electron imbalance across the membrane that generates a gradient that the cell can harness for energy via proton motive force

Which of the following is part of the endomembrane system? - Ribosomes - Cytoskeleton - Mitochondria - Flagellum - Golgi apparatus

Golgi Apparatus The endomembrane system includes the ER, the Golgi apparatus, lyosomes, and vesicles. It manufactures, processes, and packages proteins

Where are lipids made in the cell?

Smooth endoplasmic reticulum (ER)

One of the main differences between a Gram-positive and a Gram-negative bacterial cell wall is that the peptidoglycan portion of a Gram-positive cell wall is _____ as compared to a Gram-negative cell wall.

Thicker The peptidoglycan layer of gram-positive bacteria is much thicker than that of gram-negative bacteria