Ch 3 Mastering

Which step of binary fission is the reason for genetically identical daughter cells?

Replication of the bacterial chromosome

Choose the characteristics that separate the archaea from other prokaryotic cells. Select all that apply. a. Archaea lack true peptidoglycan in their cell walls. b. The cytoplasmic membrane lipids of archaea have branched or ringform hydrocarbon chains. c. The morphology of the cell is rigid and is geometric in shape, similar to a sphere or cylinder. d. All currently identified and characterized archaea have been linked as the causative agent to an animal or human disease.

- Archaea lack true peptidoglycan in their cell walls. - The cytoplasmic membrane lipids of archaea have branched or ringform hydrocarbon chains.

Choose the true statement(s) about binary fission in prokaryotic cells. a. Binary fission results in offspring, which are genetically identical to the parent cell. b. Binary fission is a type of sexual reproduction which introduces genetic variation from parent to offspring. c. Binary fission frequency differs between species and is affected by environmental conditions. d. Binary fission is a type of asexual reproduction that is simpler than mitosis.

- Binary fission results in offspring, which are genetically identical to the parent cell. - Binary fission frequency differs between species and is affected by environmental conditions. - Binary fission is a type of asexual reproduction that is simpler than mitosis.

Choose from the following statements the ones that correctly discuss reproduction using binary fission in a bacterial cell. a. Each daughter cell is an exact copy of the other, both genetically and morphologically. b. Each daughter cell will contain an equal number of organelles. c. Due to the stretching of the cytoplasmic membrane, both cells will contain a complete genome. d. The daughter cell will be a permanently smaller copy of the mother cell but will contain a complete genome.

- Each daughter cell is an exact copy of the other, both genetically and morphologically. - Due to the stretching of the cytoplasmic membrane, both cells will contain a complete genome.

Choose the true statement(s) about prokaryotic cells. a. Prokaryotes do not change shape or arrangement to enhance their survival. b. Most of a prokaryote's nutrients are obtained through diffusion. c. All prokaryotes are unicellular organisms. d. All prokaryotes lack a membrane-bound nucleus and organelles.

- Most of a prokaryote's nutrients are obtained through diffusion. - All prokaryotes are unicellular organisms. - All prokaryotes lack a membrane-bound nucleus and organelles.

Choose the true statement(s) about prokaryotic external appendages. a. Fimbriae aid in gene transfer through conjugation. b. Pili allow for adhesion, movement, and aid in gene transfer through conjugation. c. Flagella allow for motility. d. The glycocalyx promotes adhesion and interferes with phagocytosis.

- Pili allow for adhesion, movement, and aid in gene transfer through conjugation. - Flagella allow for motility. - The glycocalyx promotes adhesion and interferes with phagocytosis.

Put the following steps of bacterial replication in the correct order, starting from a parent cell. 1. Cell elongation 2. Septum formation 3. Chromosome replication 4. Separation of daughter cells

3, 1, 2, 4

How is osmosis different from simple diffusion?

Water movement is driven by the concentration of solutes rather than its own concentration.

How does water enter and exit a cell?

By simple diffusion or by use of an integral transport protein

Which of the following does not represent a shape or arrangement that a prokaryote can assume?

Clusters of bacilli form a Staph arrangement.

Which of the following molecules would be blocked by a cell membrane?

Ions

Choose the false statement about cellular transport mechanisms. a. Facilitated diffusion does not require energy and uses membrane proteins to move substances down their concentration gradient. b. Osmosis is the passive movement of water from a low-solute concentration to a high-solute concentration. c. Diffusion is the passive movement of substances from areas of low concentration to areas of high concentration. d. Active transport requires energy and uses carrier proteins to move substances against their concentration gradient.

Diffusion is the passive movement of substances from areas of low concentration to areas of high concentration.

Which of the following is NOT a step in bacterial cell division? a. Splitting apart of two new daughter cells b. Replication of the genetic material c. Cell elongation d. Disappearance of nuclear envelope

Disappearance of nuclear envelope

A cell wall is a requirement for all living bacteria. Is this statement True or False?

False

A cell wall is a requirement for all living bacteria. Is this statement True or False?

False

If you begin with six cells, how many cells would you have after three rounds of division?

Forty-eight cells

_____________ bacteria lack an outer membrane, have a thick layer of peptidoglycan, contain teichoic acid, and lack mycolic acid.

Gram-positive

Choose the false statement regarding prokaryotic plasma membranes. a. Gases, water, and small non-charged substances can diffuse through the selectively permeable plasma membrane. b. Ions and large polar substances can diffuse through the plasma membrane without assistance. c. The plasma membrane's phospholipid bilayer contains hydrophilic phosphates and hydrophobic fatty acids. d. The plasma membrane is a phospholipid bilayer that serves as barrier for a cell.

Ions and large polar substances can diffuse through the plasma membrane without assistance.

What is a hallmark of passive transport across cell membranes?

It occurs along an electrochemical gradient, and may involve the use of transport proteins.

How long does it take for the daughter cells to initiate or start the next round of replication?

No time is required -- they are ready to divide immediately after DNA replication and separation of the daughter cells is complete if conditions are right.

Why are most prokaryotic cells small?

Nutrient diffusion is most efficient for smaller cells.

Which of the following would not move freely across the cytoplasmic membrane?

Positively charged hydrogen ions

How is simple diffusion different from other types of passive transport?

Simple diffusion does not require a permease.

Choose the true statement about the Domain Bacteria a. The Domain Bacteria is made up of prokaryotes and likely originated 3.8 billion years ago. b. The Domains Bacteria and Archaea are genetically identical. c. Bacteria inhabit extreme environments and are not linked to human diseases. d. The Domain Eukarya is more closely related to the Domain Bacteria than to the Domain Archaea.

The Domain Bacteria is made up of prokaryotes and likely originated 3.8 billion years ago.

What will happen to a cell that is placed in a solution containing a high concentration of sugar, a molecule that cannot pass across the cell membrane?

The cell will lose its interior water, causing it to shrivel up and possibly die.

What would happen if the septum did not form during binary fission?

The parent cell would now have two copies of the chromosome.

What makes phospholipid membranes good at keeping some molecules out, and allowing others to freely pass?

They have both hydrophilic and hydrophobic regions.

Starting with three cells, how many cells would result from three rounds of replication?

Twenty-four

What results when a single bacterium reproduces?

Two genetically identical daughter cells

Nonspecific permeases

allow a variety of molecules to cross the cytoplasmic membrane.

All of the following are examples of inclusion bodies in prokaryotic cells except __________.

endospores

A glycoprotein

is a type of peripheral protein above that can be used as a receptor or in enzymatic functions.

Once equilibrium is reached,

molecules move, but there is no net movement in a particular direction.

Prokaryotic cells house a single circular chromosome in their __________.

nucleoid region

The peptidoglycan cell wall and the one or two membranes present also impart a three-dimensional shape to the bacterial cell. The overall shape and arrangement of bacteria are genetically determined, so that each genus of bacteria has a characteristic shape (round, rod, spiral, etc.) and arrangements of the growing cell population (individual cells, chains of cells, or clustered cells). Drag the descriptive terms to the pictured bacterial shapes

pg 69

The ability of certain bacterial cells to take on different cell shapes is known as

pleomorphism.

Which of the following arrangements is sometimes referred to as having a beads-on-a-string appearance?

streptococci

Integral proteins are mostly involved in

transport function

A positively charged sodium ion

would require the use of integral protein channels to pass through a cell membrane.

Why aren't Archaea discussed as much as bacteria?

Archaea haven't been linked to human diseases.

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. Is this statement True or False?

False

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. Is this statement True or False?

False

The thickness of this sugar-protein scaffold of peptidoglycan can be used to separate most bacteria into two groups. In your tutorial, you want to illustrate to the students that the thickness of the peptidoglycan layer can be used by microbiologists to differentiate many bacteria by only using an easy staining method that all microbiologists will have to master. This staining procedure, known as the Gram stain, is based on the retention of dyes within the cell wall for a positive result or the rinsing away of the dyes and leakage of the membrane for a negative result. A thicker cell wall will allow for retention of dye crystals that will give the bacterial cell a blue-purple color (positive result), but the thinner cell walls will not allow for the retention of these crystals during rinsing, which will mean that these cells will then be colorless unless another dye that does not require interaction with the cell wall to maintain its retention is used (negative result). In addition to differences in cell wall thickness, Gram-positive and Gram-negative bacteria also differ in the proteins and lipids associated with their cell walls, as well as the composition of their cell membranes. Gram-positive walls are composed of an underlying cytoplasmic membrane, with the thick peptidoglycan layer on the outside offering support. Proteins anchor the membrane and the cell wall together to provide support and structure between the two. Gram-negative staining walls have a different layout. You try to explain in your tutorial that even though these bacteria stain "negative" they do have a thin layer of peptidoglycan sandwiched in between two lipid bilayer membranes. Place each attribute into the bin of the bacterial group it belongs to, based on whether the bacterium is a Gram-positive or a Gram-negative cell.

Gram-positive - thick layer of peptidoglycan - teichoic acids - single lipid bilayer membrane Gram-negative - thin layer of peptidoglycan - dual lipid bilayer membranes - periplasmic space - lipopolysaccharides

Which of the following statements regarding active transport is false? a. It requires the use of a transport protein. b. It powers the diffusion of water across the cell membrane. c. It requires ATP.

It powers the diffusion of water across the cell membrane.

Considering the process of osmosis, what will occur if a bacterial cell is put into a hypotonic solution?

The cell will take on water and may lyse if its cell wall is damaged.

What enables the copied chromosomes to separate during binary fission?

The chromosomes are attached to different parts of cell membrane, which elongates and thus separates the chromosomes.

Why is no energy required in passive transport?

The concentration gradient drives the movement.

Hydrophobic molecules move across a membrane

by passive transport directly across the membrane.

Cell shape is determined by which of the following?

cell wall and cytoskeleton components

In a section that will be a brief survey of the prokaryotic bacteria, you want to give an overview of the multiple groups of bacteria and representative bacteria within each group. The groupings have been developed based on many characteristics of the bacterial cells and attempt to group together different species with similar cellular characteristics. Cellular morphology, cell wall composition, and metabolism have historically been used as means to roughly group bacteria together into different classes and genera. Current technologies have been expanding and reorganizing these groupings based on lipid content and genomic characterizations. Which of the following characteristics would NOT be used to aid in classifying a newly discovered bacterial species? a. cell wall composition b. cellular appendages c. cellular size d. nutrients required e. DNA composition

cellular size

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? Pick the answer that lists the composition of the bacterial cell wall.

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