Name KEY

Microbiology Chapter 4: Bacteria and Archaea

4.1 Bacterial Form & Function

  1. Use page 83 in your book to fill in the following table, describing the function of each bacterial cell part.
Bacterial Cell Structures and Functions
In ALL Bacterial Cells:
Structure / Function
Cell (Cytoplasmic) Membrane / A thin sheet of lipid and protein that surrounds the cytoplasm and controls the flow of materials into and out of the cell pool.
Bacterial Chromosome or Nucleoid / Composed of condensed DNA molecules. DNA directs all genetics and heredity of the cell and codes for all proteins.
Ribosomes / Tiny particles composed of protein and RNA that are the sites of protein synthesis.
Cytoplasm / Water-based solution filling the entire cell.
In SOME Bacterial Cells:
Structure / Function
S Layer / Monolayer of protein used for protection and/or attachment.
Fimbriae / Fine, hair-like bristles extending from the cell surface that help in adhesion to other cells and surfaces.
Outer Membrane / Extra membrane similar to cell membrane but also containing lipopolysaccharide. Controls flow of materials, and portions of it are toxic to mammals when released.
Cell Wall / A semi-rigid casing that provides structural support and shape for the cell.
Actin Cytoskeleton / Long fibers of proteins that encircle the cell just inside the cell membrane and contribute to the shape of the cell.
Actin Cytoskeleton / Long fibers of proteins that encircle the cell just inside the cell membrane and contribute to the shape of the cell.
Pilus / An appendage used for drawing another bacterium close in order to transfer DNA to it.
Capsule / A coating or layer of molecules external to the cell wall. It serves protective, adhesive, and receptor functions. It may fit tightly or be very loose and diffuse. Also called a slime layer, or glycocalyx.
Inclusion/Granule / Stored nutrients such as fat, phosphate, or glycogen deposited in dense crystals or particles that can be tapped into when needed.
Bacterial Microcompartments / Protein-coated packets used to localize enzymes and other proteins in the cytoplasm.
Plasmid / Double-stranded DNA circle containing extra genes.
Flagellum / Specialized appendage attached to the cell by a basal body that holds a long, rotating filament. The movement pushes the cell forward and provides motility.
Endospore / Dormant body formed within some bacteria that allows for their survival in adverse conditions.
Intracellular Membranes / Membrane on the inside side of the cell wall.
  1. Fill in the following table to describe how bacteria & archaea are different from eukaryotes.

The way DNA is packaged:
Eukaryotes have their DNA organized and packaged around proteins called histones. This DNA is housed within a nucleus.
Bacteria & Archaea have DNA that floats freely in the cytoplasm; they do NOT have a nucleus or histones.
Cell Wall makeup:
In eukaryotes, animal cells do not have cell walls and plants have cell walls made of cellulose.
In prokaryotes and archaea the cell wall is made of peptidoglycan, which is much stronger than cellulose.
Internal Structures:
Eukaryotic cells have many membrane-bound, specialized organelles. Prokaryotic cells lack membrane-bound organelles.
It’s important to note that both eukaryotic and prokaryotic cells have ribosomes for protein synthesis; ribosomes do not have membranes.
  1. A bacterial cell is organized into three levels. Fill in the following table to describe each, then refer to your answer in #1 for a review of the function of each part.

Bacterial Cell Organization
External:
1. Appendages
a. Flagella
b. Pili
c. Fimbriae
2. Surface Layers
a. S Layer
b. Glycocalyx
i. Capsule
ii. Slime Layer
Cell Envelope:
1. Outer Membrane
2. Cell Wall
3. Cell Membrane
Internal:
1. Cytoplasm
2. Ribosomes
3. Inclusions
4. Microcompartments
5. Nucleoid / Chromosome
6. Cytoskeleton
7. Endospore
8. Plasmid
9. Intracellular Membranes
  1. Unlike specialized eukaryotic cells making up a multicellular organism, each individual bacterial cell is fully capable of carrying out all necessary life activities on its own. Name three of these activities.

Reproduction, Metabolism, Nutrient Processing

  1. When do bacteria act as a group?

When they are close to one another in colonies or biofilms and communicate with each other through chemicals that cause them to behave differently than they would if they were living singly.

  1. What are nanowires?

Appendages that bacteria sometimes use to communicate with one another by transferring electrons or other substances outside the cell onto metals, such as iron.

  1. Describe how biofilms play a major role in infections disease.

Biofilms are not completely eradicated by antibiotics. For example, chronic ear infections in children are typically caused by a biofilm. Antibiotics help, but do not cure so additional procedures must be used, such as placing tubes in the child ear.

  1. Coccus typically means spherical in shape, but also refers to several other shapes. Name them.

Oval or bean-shaped

  1. Bacillus typically refers to a rod shape. How does this shape vary from species to species?

Blocky, spindle-shaped, round-ended, long and threadlike (filamentous), club-shaped, or drumstick-shaped

  1. Describe the shape of coccobacillus and draw a simple picture.

A short, plump rod, that is sometimes gently curved (vibrio)

  1. Spirillum typically means spiraled in shape, but there are several forms. Describe the spirochete shape.

A flexible form that resembles a spring.

  1. How are micrographs useful in viewing the shape of bacterial cells?

They allow the scientist to view the cells in 3-D form.

  1. What are pleomorphisms and what causes them?

When cells of a single species vary in size and shape, caused by nutritional or slight genetic differences.

  1. Bacterial cells often group themselves together in specific patters. Describe the tetrad and sarcina patterns of grouping in cocci shaped bacteria.

Tetrads refers to groups of four and sarcina refers to a cubical packet of 8, 16, or more cells.

  1. On page 86, answer the 5 questions in 4.1 Learning Outcomes – Assess Your progress.
  1. List the structures all bacteria possess.
  1. Identify at least four structures that some, but not all, bacteria possess.
  1. Describe the three major shapes of bacteria.
  1. Describe other more unusual shapes of bacteria.
  1. Provide at least four terms to describe bacterial arrangements.

*There will be a 60 Point Multiple Choice Test based off of section 4.1 in the book and this notes packet. It will consist of 30 Multiple Choice questions, at 2 points each.

4.2 External Structures

  1. What are appendages and what two groups can they be divided into?

Accessory structures that sprout from the surface of bacteria.

Two groups:

  1. Provide Motility
  2. Flagella
  3. Axial Filaments
  4. Provide Attachment
  5. Fimbriae
  6. Pili
  1. What is a flagellum? Describe its function.

An appendage that provides motility and the ability to swim though an aqueous habitat.

  1. What are the three structures making up a flagellum and how do they work together to allow unique movement of the bacterial cell?
  1. Filament – helical structure made up of proteins
  2. Hook (Sheath) – Anchored to the cell by the basal body
  3. Basal Body – Stack of rings firmly anchored through the cell wall to the cell membrane and outer membrane

This arrangement permits the hook with this filament to rotate 360o!

  1. How common is the presence of flagella in coccus, bacillus and spirilla shaped bacteria?

Only a small number of coccus have flagella.

About half of bacillus have flagella.

All spirilla have flagella.

  1. Fill in the table below to describe the number and arrangement patterns of flagella.

Number and Arrangement Patterns of Flagella
  1. Polar Arrangement - The flagella are attached at one or both ends of the cell.
  1. Monotrichous - Single flagellum
  1. Lophotrichous– Small bunches or tufts of flagella emerging from the same site
  1. Amphitrichous– Flagella at both poles of the cell

  1. Peritricous Arrangement– Flagella are dispersed randomly over the surface of the cell

  1. Oftentimes, the presence of flagella gives the bacteria special abilities. Some of the abilities include chemotaxis and phototaxis. Describe chemotaxisandphototaxis.
  1. Chemotaxis– Some bacteria with flagella can detect specific chemicals in the environment and move towards it.
  1. Phototaxis– Some bacteria with flagella can detect light in the environment and move towards it. (Important for photosynthetic bacteria.)
  1. Aside from flagella, some bacteria have additional appendages, but instead of being used for movement, they are used for sticking to other things. Describe the pilus and the fimbria.
  1. Pilus–a long, rigid tubular structure made of a special protein called pilin. These are found on gram-negative bacteria and allow for bacterial “mating.” The pilus is like a tunnel that connects two bacterial cells, allowing them to exchange genetic material.
  1. Fimbria– small, bristle-like fibers sprouting off the surface of bacterial cells, allowing bacterial cells to stick to one another as well as surfaces.

*The ability to attach allows bacteria to become pathogenic more easily, causing disease. Medical advancements are attempting to make new forms of antibiotics that would attack and destroy the pilus or fimbria instead of the cell wall.

  1. Fill in the blanks: Pilin is the protein that makes up a Pilus. Pili have only been found on gram-negative bacteria. Pili are used in the “mating” process between bacteria, known as conjugation.
  2. What is conjugation?

The partial transfer of DNA from one cell to another via a pilus.

  1. What is an S layer?

Single layers of thousands of copies of a single protein linked together. They are often called “the armor” of a bacterial cell because bacteria only produce an S layer when they live in a hostile environment.

  1. What is a glycocalyxand when is it called a capsule?

A coating of repeating polysaccharide units (carbohydrates) that may or may not include some protein. This protects the cell and may help it to adhere to surfaces in its environment.

A glycocalyx is called a capsule when it is bound more tightly to the cell than a slime layer is and it is denser and thicker.

  1. How might a glycocalyx be beneficial for the bacterium, but a problem for humans?

Glycocalyxs are often formed in pathogenic bacteria. This is beneficial for the bacteria because it protects it and enables it to live and survive in harsh environment that would otherwise kill it. It is a problem for humans because it means that when a person is infected it is very hard to treat. Ex. Streptococcus pneumoniae, which causes pneumonia.

  1. On page 91, answer the 2 questions in 4.2 Learning Outcomes – Assess Your progress.
  1. Describe the structure and function of five different types of bacterial external structures.
  1. Explain how a flagellum works in the presence of an attractant.

*There will be a 30 Point Multiple Choice Quiz based off of section 4.2 in the book and this notes packet. It will consist of 15 Multiple Choice questions, at 2 points each.

SKIP 4.3 The Cell Envelope: The Boundary Layer of Bacteria

4.4 Bacterial Internal Structures

  1. Fill in the following table to state the function of each internal structure.

Internal Structure / Function
Cytoplasm / A gelatinous solution encased by the cell membrane. Biochemical and synthetic activities occur here and it is made of 70-80% water.
Nucleoid / A dense area of the cell where DNA congregates.
Plasmid / Non-essential, circular DNA, giving the bacteria a special trait. Ex. antibiotic resistance
Ribosome / Non-membrane bound structure where protein synthesis occurs.
Inclusion Bodies (Inclusions) / A storehouse for nutrients in bacterial cells. When the environment become depleted of necessary nutrients the bacteria can draw upon this reserve.
  1. What are metachromatic granules?

Part of a building block that makes up nucleic acids and ATP. They stain red/purple when dyed.

  1. What are endospores and what makes them so resistant to heat?

A survival mechanism where a bacterium is in an environment where it can no longer live so it makes a hard shell around it and goes into “hibernation” until the environment becomes more fit and it can“come back to life.”

  1. What causes a cell to go from the vegetative state to a sporulating state?

The depletion of nutrients in the environment, especially a nitrogen or carbon deficiency.

  1. Describe the steps of the sporulation cycle.

  1. Fill in the following table to describe the medical significance of some commonly encountered bacterial spores.

Bacterial Spores / Medical Significance
Bacillus anthracis / It perseveres in endospore form and has been used in bioterrorism.
Clostridium / Includes pathogens such as C. tetani, and C. perfringens (which causes gas gangrene - a bacterial infection that produces gas in tissues in gangrene. This deadly form of gangrene usually is caused by Clostridium perfringens bacteria. It is a medical emergency. About 1000 cases of gas gangrene occur yearly in the United States.)
C. tetani / Causes tetanus (lockjaw – causes muscle spasms and convulsions);most people are vaccinated for this
C. botulinum / Deadly form of food poisoning
  1. On page 100, answer the 2 questions in 4.4 Learning Outcomes – Assess Your progress.
  1. Identify five structures that may be contained in bacterial cytoplasm.
  1. Detail the causes and mechanisms of sporogenesis and germination.

*There will be a 60 Point Multiple Choice Test based off of section 4.4 in the book and this notes packet. It will consist of 30 Multiple Choice questions, at 2 points each.

4.5 The Archaea: The Other “Prokaryotes”

  1. Are Archaea more closely related to prokaryotes or eukaryotes? Explain.

Eukaryotes based on ribosomal RNA sequences that are not found in bacteria, and their protein synthesis and ribosomal subunit structures being similar. (In other words, their genetics are more similar.)

  1. Fill in the following table to describe the function of the given Archaea and where we find them.

Archaea / Function / Environment
Methanogens / Can convert CO2 and H2 into methane gas (CH4) / Anaerobic swamp mud, the bottom sediments of lakes and oceans, and the digestive systems of animals (such as cows.)
Halophiles / Require salt to grow. Sometimes gives bodies of water its color (Ex. Lake Natron in the Great Rift Valley on the border of Tanzania & Kenya make the lake appear red. / The saltiest places on earth, the inland seas, salt lakes, salt mines, and inside salted fish.
Psychrophililes / Archaea that are adapted to growing at very low temperatures (extreme cold). / Ice caps, glaciers
Hyperthermophiles / Archaea that are adapted to growing at very high temperatures. / Volcanic waters and solids and submarine vents.
  1. On page 102, answer the question in 4.5 Learning Outcomes – Assess Your progress.
  1. List some differences between Archaea and bacteria.

4.6 Classification Systems for Bacteria and Archaea

  1. How did Bergey’s Manual classify bacteria and Archaea?

Based on phenotypic traits of bacteria, such as shape, cultural behavior, and biochemical reactions.

  1. How did Bergey’s Manual of Systematic Bacteriology classify bacteria and Archaea?

Combines phenotypic relatedness with rRNA sequencing. (rRNA is ribosomal RNA)

  1. How did Bergey’s Manual of Determinative Bacteriology classify bacteria and Archaea?

Based entirely on phenotypic characteristics as categorized by traits commonly assayed in clinical, teaching and research labs. Used by scientists that need to identify bacteria but don’t need to know their evolutionary backgrounds. This is a narrower form of Bergey’s Manual mentioned in #1.

  1. Fill in the following table to describe the four types of taxonomic scheme.

Taxonomic Scheme / Description
Gracilicutes / Gram-negative and very thin
Firmicutes / Gram-positive and thick and strong
Tenericutes / Lack cell walls and are soft
Mendosicutes / Archaea
  1. Fill in the following table to describe the three types of diagnostic scheme.

Diagnostic Scheme / Description
Aerobic / Bacteria that use oxygen in metabolism.
Anaerobic / Bacteria that do not use oxygen in metabolism.
Facultative / Bacteria that may or may not use oxygen in their metabolism, depending on the environment they are in.
  1. Subspecies, Strain and Type are all synonyms that mean what?

Bacteria of the same species that have differing characteristics.

  1. On page 105, answer the 3 questions in 4.6 Learning Outcomes – Assess Your progress.
  1. Differentiate between Bergey’s Manual of Systematic Bacteriology and Bergey’s Manual of Determinative Bacteriology.
  1. Name four divisions ending in –cutes and describe their characteristics.
  1. Define a species in terms of bacteria.

*There will be a 100 Point Test on all of Chapter 4. There will be 40 Multiple Choice, worth 2 points each and 2 Open Ended worth 10 points each.