BSC-116-001 Chapter 27

What is the function of fimbriae?

A. They are used in motility.
B. They are used to transfer DNA during conjugation.
C. They are components of the outer cell wall in gram-negative bacteria.
D. They protect the cell from dehydration.
E. They are used to attach the cell to its substrate or to other prokaryotes.

E. They are used to attach the cell to its substrate or to other prokaryotes. They are hair-like projections that aid in attachment. They are also known as attachment pili to distinguish them from the pili used in conjugation.

How does the large amount of genetic variation observed in prokaryotes arise?

A. The mutation rate in prokaryotes is much higher than in eukaryotes.
B. They have extremely short generation times and large populations.
C. They can exchange DNA with many types of prokaryotes by way of horizontal gene transfer.
D. They have a relatively small genome.
E. The second and third answers are correct.

E. The second and third answers are correct. The short generation times and large population sizes in most prokaryotic species, coupled with their ability to exchange genes, helps to increase genetic variability beyond what we would expect in asexually reproducing organisms.

Genes for the resistance to antibiotics are usually located _____.

A. in mitochondria
B. on the main chromosome
C. on plasmids
D. in eukaryotic cells
E. on the outside of the cell wall

C. on plasmids Genes for the resistance to antibiotics are usually located on plasmids.

gram-positive bacteria

1.) Have a thick layer of peptidoglycan 2.) Appear purple after Gram staining 3.) Alcohol rinse does not remove crystal violet

gram-negative bacteria

1.) Have a thin layer of peptidoglycan 2.) Appear pink after Gram staining 3.) Have an outer membrane as part of their cell-wall structure 4.) Alcohol rinse does remove crystal violet

gram-positive/ gram-negative bacteria

1.) Both have a plasma membrane

Autotroph

Require energy only from inorganic sources

Heterotroph

Require energy from atlas one organic nutrient

Phototrophs

Use light as energy source

Chemotrophs

Use chemicals as energy source

Azotobacter is a genus of bacteria that live in soil and have the following characteristics:
– They are bacilli.
– They are gram-negative.
– They are obligate aerobes.
– They can fix nitrogen. (Unlike some other nitrogen-fixing bacteria, which associate with the roots of plants, Azotobacter species are free-living.)

1.) They use O2 for cellular respiration 2.) They can convert atmospheric nitrogen to ammonia 3.) They are shaped like rods 4.) They have a relatively thin layer of peptidoglycan in their cell wall

Cocci

spherical prokaryotes

Bacilli

rod-shaped prokaryotes

Spirilla

spiral prokaryotes

Bacteria that live around deep-sea, hot-water vents obtain energy by oxidizing inorganic hydrogen sulfide belched out by the vents. They use this energy to build organic molecules from carbon obtained from the carbon dioxide in seawater. These bacteria are _____.

A. chemoheterotrophs
B. photoheterotrophs
C. chemoautotrophs
D. photoautotrophs

C. chemoautotrophs They use inorganic molecules (in redox reactions) for energy, and carbon dioxide for carbon.

Which statement is true about obligate anaerobes?

A. They will use O2 if it is present, but can obtain energy by fermentation if needed.
B. They obtain energy by oxidizing ferrous ions.
C. They use O2 for cellular respiration and cannot grow without it.
D. They live exclusively by cellular respiration or by anaerobic respiration.
E. They are poisoned by O2.

E. They are poisoned by O2. Some obligate anaerobes live exclusively by fermentation; others extract chemical energy by anaerobic respiration, in which substances other than O2 accept electrons at the "downhill" end of electron transport chains.

The prokaryotic cells that built stromatolites are classified as _____.

A. proteobacteria
B. chlamydias
C. spirochetes
D. gram-positive bacteria
E. cyanobacteria

E. cyanobacteria Cyanobacteria built stromatolites.

The prokaryotic cells that were the first to add significant quantities of oxygen to Earth’s atmosphere are classified as _____.

A. proteobacteria
B. chlamydias
C. spirochetes
D. gram-positive bacteria
E. cyanobacteria

E. cyanobacteria Cyanobacteria are aerobic photosynthesizers.

Streptococcus pyogenes is classified with _____.

A. proteobacteria
B. chlamydias
C. spirochetes
D. gram-positive bacteria
E. cyanobacteria

D. gram-positive bacteria S. pyogenes attracts the violet Gram stain.

Organisms that can cause nongonococcal urethritis are classified with _____.

A. proteobacteria
B. chlamydias
C. spirochetes
D. gram-positive bacteria
E. cyanobacteria

B. chlamydias Chlamydia trachomatis causes nongonococcal urethritis.

The chemoheterotroph Proteus vulgaris is a rod-shaped bacterium classified with _____.

A. proteobacteria
B. chlamydias
C. spirochetes
D. gram-positive bacteria
E. cyanobacteria

A. proteobacteria Proteus vulgaris is classified with proteobacteria.

Spiral-shaped bacteria are likely to be placed with _____.

A.proteobacteria
B. chlamydias
C. spirochetes
D. gram-positive bacteria
E. cyanobacteria

C. spirochetes The name of these organisms provides the answer to the question.

The prokaryotic organisms most likely to be found living in salt ponds are the _____.

A. thermophiles
B. methanogens
C. Korarchaeota
D. extremophiles
E. halophiles

E. halophiles These archaea live in salty environments such as the Dead Sea.

How are archaeans most similar to bacteria?

A.the structure of their cell walls
B. methanogenesis
C. the occurrence of introns in their chromosomes
D. nucleotide sequence of small subunit ribosomal RNA
E. the shape of their chromosomes and plasmids

E. the shape of their chromosomes and plasmids Prokaryotes typically have circular chromosomes and plasmids

An ecological relationship between organisms of different species that are in direct contact can best be described as _____.

A. taxis
B. commensal
C. symbiotic
D. mutualistic
E. parasitic

C. symbiotic This is the definition of symbiosis.

Which statement about endotoxins is true?

A. The source of endotoxins is endospores.
B. Endotoxins are released only when bacteria die and their cell walls break down.
C. Endotoxins are proteins secreted by prokaryotes.
D. An example of a prokaryote that produces endotoxins is Clostridium botulinum.
E. Endotoxins are components of the cell wall of gram-positive bacteria.

B. Endotoxins are released only when bacteria die and their cell walls break down. Endotoxins are a component of the outer membrane of gram-negative bacteria.

Bioremediation is _____.

A. the use of prokaryotes in producing pharmaceutical products
B. the modification of prokaryotes for industrial purposes
C. the use of organisms to remove pollutants from the environment
D. the use of biological processes to remedy diseases
E. the use of prokaryotes in producing transgenic organisms

C. the use of organisms to remove pollutants from the environment This is the general use of the term bioremediation.

Select the valid comparison between eukaryotes and prokaryotes.

A.Eukaryotes are far more metabolically diverse than prokaryotes.
B. Prokaryote cells have simpler internal structure and genomic organization than eukaryotic cells.
C. The total biomass of eukaryotes is approximately ten times the total biomass of prokaryotes.

B. Prokaryote cells have simpler internal structure and genomic organization than eukaryotic cells. Read about the internal and genomic organization of prokaryotes.

Which of the following processes contributes to genetic recombination in prokaryotes?
Which of the following processes contributes to genetic recombination in prokaryotes?
A.) Transduction
B.) Mutation
C.) Meiosis

A.) Transduction In transduction, bacteriophages carry bacterial genes from one host cell to another, producing a recombinant bacterial genome. Read about the other processes that contribute to genetic recombination in prokaryotes.

Peptidoglycan

A polymer composed of modified sugars cross-linked by short polypeptides. This molecular fabric encloses the entire bacterium and anchors other molecules that extend from its surface.

Capsule

Is a sticky layer of polysaccharide or protein that surrounds the cell wall of many prokaryotes.

Endospores

Resistant cells bacteria develop when they lack an essential nutrient in a way to withstand harsh conditions.

Fimbriae

Hairlike appendages some prokaryotes use to stick to their substrate or to one another.

Pili

Appendages (longer than fimbriae) that pull two cells together prior to DNA transfer from one cell to another.

Taxis

A directed movement toward or away from a stimulus.

Nucleoid

Where the chromosome is located in a prokaryote; region of the cytoplasm that is not enclosed by a membrane.

Plasmids

Small rings of independently replicating DNA molecules.

Transformation

Where the genotype and possibly phenotype of a prokaryotic cell are altered by the uptake of foreign DNA from its surroundings.

Transduction

When phages carry prokaryotic genes from one host cell to another.

Conjugation

DNA is transferred between two prokaryotic cells that are temporarily joined.

F factor

A particular piece of DNA that allows the ability to form pili and donate DNA during conjugation.

R plasmids

"resistance genes" which code for enzymes that specifically destroy or otherwise hinder the effectiveness of certain antibiotics, such as tetracycline or ampicillin.

Obligate aerobes

Must use O2 for cellular respiration.

Obligate anaerobes

Poisoned by O2; some live exclusively by fermentation; others extract chemical energy by anaerobic respiration.

Facultative anaerobes

Can use O2 if its present but can also carry out fermentation or anaerobic respiration.

Nitrogen fixation

Some cyanobacteria and some methanogens convert atmospheric nitrogen (N2) to ammonia (NH3).

Extreme halophiles

Live in highly saline environments.

Extreme thermophiles

Thrive in very hot environments.

Methanogens

Arachaea that release methane as a by-product of their unique ways of obtaining energy.

Decomposers

Break down dead organisms and waste products unlocking supplies of carbon, nitrogen, and other elements.

Symbiosis

An ecological relationship in which two species live in close contact of one another.

Mutualism

+ +

Commensalism

+ 0

Parasitism

+ –

Pathogens

Parasites that cause disease.

Exotoxins

Are proteins secreted by certain bacteria and other organisms.

Endotoxins

Are lipopolysaccharide components of the outer membrane of gram-negative bacteria. They are only released when bacteria die and their cell walls break down.

Genetic variation in bacterial populations cannot result from

A. transduction
B. conjugation
C. mutation
D. meiosis

D. meiosis

Photoautotrophs use

A. light as energy source and CO2 as a carbon source.
B. light as energy source and methane as a carbon source.
C. N2 as an energy source and CO2 as a carbon source.
D. CO2 as both an energy source and a carbon source.

A. light as energy source and CO2 as a carbon source.

Which of the following involves metabolic cooperation among prokaryotic cells?

A. binary fission
B. endospore formation
C. biofilms
D. photoautotrophy

C. biofilms

Bacteria perform the following ecological roles. Which role typically does not involve symbiosis?

A. skin commensalist
B. decomposer
C. gut mutualist
D. pathogen

B. decomposer

Plantlike photosynthesis that releases O2 occurs in

A. cyanobacteria
B. gram-positive bacteria
C. archaea
D. chemoautotrophic bacteria

A. cyanobacteria