Chapter 4: Bacterial Anatomy

01/30/2025- finished flashcard set ~X.

What are the characteristics shared by all living organisms?

• Heredity (genetic material/ DNA)

• Reproduction (increase in numbers)

• Growth (increase in size)

• Development

• Metabolism

• Responsiveness (ability to change internal or external properties in reaction to a change in condition)

• Transport

Are viruses living?

No

What are the general characteristics of Eukaryotic cells?

• Present nucleus.

• present internal membranes.

• include all living organisms other than bacteria.

What are the general characteristics of prokaryotic cells?

• Absent nucleus

• Absent Internal membranes

• Include bacteria only

What are the 3 appendages types?

• Flagella (flagellum)

• Pilli

• Fimbriae

What are the 2 groups of appendages based on?

• Motility

• Attachment or channels

What is the term associated with bacteria that have flagella?

Motile

What is the term associated with bacteria that do not have flagella?

Nonmotile

What are the 3 structural components of prokaryotic flagella?

• Filament

• Hook

• Basal body

How many rings of integral proteins are in the flagella of gram + bacteria?

Two rings

How many rings of integral proteins are in the flagella of gram - bacteria?

Four rings

How do prokaryotic flagella move?

it propels

How do bacterial flagella move?

They move by “runs” and “tumbles”.

• Runs are in counter clockwise flagellar rotation and move in a single direction.

• Tumbles are in clockwise flagellar rotation and have abrupt/random changes.

Do flagellated eukaryotes move the same way as flagellated prokaryotes?

No

What are the 5 arrangements of flagella?

• Atrichous

• Monotrichous

• Lophotrichous

• Amphitrichous

• Peritrichous

Atrichous

without flagella

Monotrichous

One flagellum located at a polar end.

Lophotrichous

A cluster of flagella located at one end. “tufts”

Amphitrichous

Single flagellum or cluster of flagella located at each polar end.

Peritrichous

Flagella found laterally; non- polar.

What are the periplasmic flagella (endoplasmic)?

• Spirochetes: spiral shaped bacteria can have flagella at both ends that tightly wrap (spiral) around a cell instead of protruding. The flagella is an endoflagella that forms an axial filament that wraps around the cell between membrane & outer membrane.

• "Corkscrew” movement is made by endoflagella to rotate leading to the rotation of axial filament to rotate.

  • Treponema pallidium (syphilis)

  • Borrelia burgdorferi (lyme disease)

• Nonmotile will only exhibit “Brownian movement”.

What are fimbriae?

sticky, bristle like extensions of bacteria.

What are the function of fimbriae?

• Adhesion to one other bacteria or environment.

• Used to move across a substrate or to one another.

• Increases pathogenicity.

What is a bacterial example with lots of fimbriae?

Neisseria gonorrhoeae (gonorrhea)

Define pili and it’s function.

Tubules of protein that are on Gram - bacteria.

• Mediate the transfer of DNA from 1 cell to another.

What comprises the Cell Envelope in a bacterial cell?

• Glycocaylx

• Cell wall

• Cell membrane

What is the function of the Cell Envelope?

To provide a single protective unit

How many types of glycocalyx are there?

2 types:

• Capsule: firmly attached with repeated unit of organic chemicals bonded to the cell.

• Slime layer: loose and water soluble.

Where are biofilms likely to form in the patient?

on/in artificial valves, joints, hips, catheters, etc.

What are the general steps in biofilm development?

• After attachment, colonizers begin to multiply.

• Glycocalyx with fimbriae, pili, capsules, or slime layers accumulate. This develops the biofilm matrix and create a microhabitat for other microbes.

What is quorum sensing?

It is a several stage process that self-monitors for:

• Cell density

• Secretions of chemical signals

• Genetic Activation

It also allows biofilm to react and/or function as a unit by allowing:

• Genetic transfer

• Production of virulence factors

• Antibiotic resistance

Cell walls are present in all bacteria with what exception?

mycoplasma & L-form (A condition resulting from a mutation).

What is peptidoglycan composed of and what joins them together?

N-acetylglucosamine (NAG) and N-Acetylmuramic (NAM)

What are the functions of the cell wall?

• Give the cell its shape

• Provide protection against osmotic changes

What are the 2 principal types of cells within bacteria? How can they be differentiated?

They can be differentiated by the Gram stain.

• Gram positive - stains purple

• Gram negative - stains pink

What is the difference between Gram + and Gram - bacteria?

Gram + bacteria (ex. Staphylococci):

• Thick Peptidoglycan layer

• Teichoic acid

• No outer membrane

• Shows purple in Gram stain

Gram - bacteria (ex. E.Coli)

• Thin peptidoglycan layer

• NO teichoic acid

• Has an outer membrane external to the cell wall

• Shows pink in Gram stain.

What molecule gives the Gram + bacteria an overall negative charge?

Teichoic acid

What molecules give Gram - bacteria an overall negative charge?

Lipopolysaccharide (LPS)

What is lipid A?

• Acts as an endotoxin in some species when lipid A is released. May trigger inflammation, shock, blood clotting…

• Endotoxins are only lipid A. Only gram - have this.

• We are exposed to lipid A when gram - bacteria are dividing or breaking down.

What are the functions of the cell membrane?

NOTE: Absolute requirement for all living cells.

• Retains cytoplasm.

• Serves as a selectively permeable membrane or semi-permeable membrane.

• Serves as a DNA anchor during binary fission.

• Contain enzymes for cell wall synthesis.

• Location of enzymes used to produce ATP for the cell.

• Forms finger-like pockets into cytoplasm- mesosomes - to increase surface area.

• Contains the transport systems.

• Anchors bacterial flagella.

What does the cytoplasm consist of?

• Gelatinous solution inside cells

  • Sugars

  • Amino acids

  • Salts

• 70-80% water.

• Contains:

  • Inclusions

  • Endospores

  • Nonmembranous organelles

    • Ribosomes

Where is DNA located and in what form?

In the nucleoid region located near the cell membrane. Chromosomes are located here and are in a single, circular molecule form containing ~ 4,000 genes.

What is a plasmid and its advantages?

a small, circular piece of DNA that exists and replicates independently of the bacteria’s chromosome(s). It is present in some but not all bacteria.

Advantages:

• Antibiotic resistance

• increases pathogenicity

• creates metabolic pathways

What intracellular organelle synthesizes proteins?

Ribosomes

Are bacterial ribosomes solid or consist of 2 subunits?

Composed of 2 subunits which are both polypeptide & ribosomal RNA (rRNA).

What values are associated with prokaryotic and eukaryotic ribosomes?

“S”= Svedberge unit

50+30 ≠ 70

What is an endospore?

Dormant bodies that are highly resistance to desiccation, staining, disinfection, chemical and radiation exposure, heating, and freezing.

What 3 genera form endospores?

Gram + ONLY genera such as Bacillus, Clostridium, and Clostridiodes.

What are the benefits of forming endospores?

• High resistance to elimination methods

• Increases pathogenicity

Are endospores indestructible?

No. pressurized steam at 120 C for 20-30 minutes will destroy it.

What determines bacterial shape?

its cell wall.

What is a coccus?

Spherical shaped cells.

What is a bacillus?

Straight rod shaped cells.

What are examples of spiral or curved bacterium shape?

• Spirillum- cell is coiled like a spring and is rigid.

• Spirochete- cell is coiled like a spring but is flexible.

• Vibrio- cell is curved but is not a complete spiral.

Describe individual coccus cells arrangement

Cells separate following binary fission resulting in identical individual cells.

Describe Diplococcus arrangement

After the first division, daughter cells remain together. With repeated divisions the cells separate, resulting in only 2 cells remaining side by side.

Describe Streptococcus arrangement

A long chain of coccal cells

Describe Tetrad arrangement

4 coccal cells forming a “square”.

Describe Sarcinae arrangement

Results in a cube of 8 coccal cells.

Describe Staphylococcus arrangement

Cell that have been formed in clusters, seemingly randomly.

Describe individual bacilli cells arrangement

individual straight rod shaped cells

Describe Diplobacillus arrangement

2 bacilli cells adhering end to end

Describe Streptobacillus arrangement

A long chain of bacilli cells lying end to end resembling a train of boxcars.

Describe Palisade bacilli arrangement

Appear in clusters lying side-by-side like match sticks or a picket fence.

Define pleomorphic arrangement

An arrangement entailing a variety of shapes due to a lack of a rigid cell wall.

Where can the pleomorphic arrangement be seen?

• Mycoplasmas (wall-less bacteria)

• L-forms

• Protozoans (Eukaryotic)

What are the 2 major taxonomic groups of prokaryotic cells?

Archaeae (most primitive and extreme) and bacteria.

Define Species

A collection of bacterial cells which chare an overall similar pattern of traits in contrast to other bacteria whose pattern differs significantly.

Define Strain (or variety)

A culture derived from a single parent that differs in structure or metabolism from other cultures of that species.

• Pigmented and nonpigmented strains

• Flagellated and non-flagellated strains