Chapter 4: Bacteria and Archaea Vocabulary

Vocabulary practice cards covering key structures, classification systems, cell envelope variations, and traits of bacteria and archaea from Chapter 4.

bacteria and archaea

nuclear material that is free in the cytoplasm

they are different from eukaryotes

dna packaging

Bacteria and archaea have nuclear material that is free in the cytoplasm

internal structures

Bacteria and archaea: no membrane-bound organelles

cell membrane

controls what enters and leaves

ribosomes

makes protein

chromosome

contains the bacterial DNA/ genetic information

cell wall

provides structural support and protection for the cell and prevents it from busting

flagella

helps bacteria move

pili

hair like structure

attachment and some cases dna transfer

fimbriae

short, hair-like projections that enable bacteria to attach to surfaces and other cells.

hooks

Provide adhesion but not locomotion

• Flagella can also be used for attachment in some species

S layer

A protective outer layer composed of protein or glycoprotein found in some bacteria and archaea, providing structural support and protecting against environmental stresses.

inclusions

storage areas for nutrients/materials inside the cell

endospores

extremely resistant structures that help bacteria survive harsh conditions

All bacteria crc

cell membrane

ribosomes

chromosomes

most bacteria c

cell wall

some bacteria FPFSIN

Flagella

pilli

fimbriae

s layer

inclusions

endospores

Average bacterial size

The standard physical size of a bacterial cell, measuring approximately $1\,\mu m$ .

Thiomargarita namibiensis:100 to 750 μm

• Nanobacteria: 0.05 to 0.2 μm

bacteria

lives as a community and can form biofilms, providing advantages for survival and growth.

nanowires

Think of nanowires as tiny electrical wires coming from bacteria and transfers electrons

Coccus

A cell shape that is spherical or ball-shaped, oval

bean-shaped

pointed

Bacillus

A bacterial cell shape that is cylindrical or rod-like.

filamentous

club shaped

vibro

curved

Pleomorphism

The property where cells of a single species vary in shape and size due to individual variations in cell wall structure.

cocci ADTSSS

single

diplococci

tetrads

staphylococci

streptococci

sarcina

Single

diplococci

pair

tretrads

groups of four

staphylococci and micrococci

irregular clusters

streptococci

chains of a few to hundreds of cells

Sarcina

A cubical packet arrangement consisting of eight, sixteen, or more cocci cells.

Bacilli PSD

palisades

strepobacilli

diplobacilli

Palisades

cell of a chain remming partially attached and fold back creating a side by side row of cells

streptobacilli

chains of cells

diplobacilli

pairs of cells with their ends attached

to major appendages

flagella

fimbriae

Flagella and axial filaments:

little propellers

motility

Three parts:

filament, hook, and basal body

Polar arrangement

flagella at or both ends

Monotrichous

single flagellum

Lophotrichous

small bunches or tufts

Amphitrichous

flagella at both poles of the cell

Peritrichous

lagella are dispersed randomly over the surface of the cell

Fine points of flagella function

1. Chemotaxis

2. Runs and tumbles

Chemotaxis

movement in response to chemical signals

Axial filaments

Periplasmic, internal flagella enclosed in the space between the cell wall and outer membrane of spirochetes that impart a twisting motion.

Pilus

1. made of pilin, used in conjugation

Provide adhesion but not locomotion

S layer

is a single layer of protein, “armor”

Glycocalyx

Repeating polysaccharide units that may or may not include protein

slime layer

Forms loosely around the cell

• Protects the cell from loss of water and nutrients

Capsule

More tightly bound to a cell than a slime layer

• Denser and thicker than a slime layer

 more difficult for phagocytes to kill

cell envelope

1. multilayer structure of two or three structures

Gram-positive cell envelope

A two-layered cell boundary consisting of a thick cell wall composed primarily of peptidoglycan and an inner cytoplasmic membrane.

Gram-negative cell envelope

A three-layered cell boundary consisting of an outer membrane, a thin cell wall of peptidoglycan, and an inner cytoplasmic membrane.

Peptidoglycan

1. glycan molecules cross-linked with peptides

2. Antimicrobial drugs (penicillin) target the cell wallFound in the cell walls of most bacteria

   • Unique macromolecule composed of glycan chains cross-

   linked with short peptide fragments

   • Provides a strong but flexible support framework

1. The gram-positive cell wall

Homogeneous thick sheath of peptidoglycan

Teichoic acid and Lipoteichoic acid

Acidic polymers functioning in cell wall maintenance and enlargement embedded within the thick peptidoglycan layer of gram-positive bacteria.

1. Nontypical cell walls

1. Mycobacterium, Nocardia 

2. Mycolic acid (waxy)

3. Acid-fast stain: tuberculosis and Hansen’s disease

Mycobacterium

composed of unique lipids

Mycolic acid

Very-long-chain fatty acid

• Contributes to pathogenicity of these organisms

• Makes them resistant to certain chemicals and dyes

Mycoplasmas

Bacteria that naturally lack a cell wall and exhibit pleomorphic shapes.

1. Mycoplasmas lack a cell wall

2. Pleomorphic mycoplasma

Cytoplasmic membrane structure

1. Lies under the cell wall

2. Lipid bilayer with embedded proteins

Functions of cytoplasmic membrane

1. Transport

2. Permeable

The gram-negative outer membrane (OM)

1. Lipopolysaccharide (LPS)

2. Endotoxin: stimulates fever and medical shock

3. Porin proteins

1. Lipopolysaccharide (LPS)

Polysaccharide chains function as cell markers and receptors

Endotoxin

stimulates fever and shock reactions

Porin proteins

Completely span the outer membrane

• Only allow relatively small molecules to penetrate

• Size can be altered to block the entrance of harmful chemicals

• Act as a defense against certain antibiotics

Gram stain results

1. Differential stain

2. Crystal violet, Gram’s iodine, alcohol, safranine

3. Gram-positive: purple and gram-negative: pink

1. Difference in cell envelope alters response

1. Antimicrobial resistance

2. Disinfectants

Proteins Lipid Macromolecules

in the outer cell wall of gram-positive bacteria canbe toxic

in the cell wall of Mycobacterium can be harmful to human cells

in the cell wall are foreign to humans andcan stimulate antibody production

Cytoplasm

1.  made up of 70−80% water

Cell pool contains

sugars, amino acids, and salts

Bacterial chromosomes and plasmid

1. The sources of genetic information

Nucleoid

1. dense are of the cell

Plasmids

Nonessential, double-stranded circular strands of DNA that can be passed between bacteria during conjugation and often carry antibiotic resistance traits.

Ribosomes

1. Sites of protein synthesis

1. Comprised of ribosomal RNA and protein

2. Bacterial ribosomes serve as targets for some antibiotics

Dispersed throughout the cytoplasm, often found in chains

Inclusion bodies and microcompartments

Storage sites for nutrients during periods of abundance

1. Inclusion bodies: store nutrients

2. Metachromatic granules

3. Bacterial microcompartments

The cytoskeleton

Actin-like proteins found in rod-shaped and spiral bacteria

Contribute to cell shape

• Potential target for antibiotic development

Bacterial endospore

A dormant, highly resistant cell structure produced by certain bacteria to survive severe conditions such as extreme heat, drying, freezing, radiation, and chemicals.

1. Two-phase life cycle

Vegetative cell: metabolically active

• Endospore: inert, resting condition

Sporulation

spore formation induced by environmental conditions

1. Endospore formation and resistance

1. Induced by depletion of nutrients

2. Endospores can withstand heat, drying, freezing, radiation, and chemicals

1. The germination of the endospores

1. Breaking of dormancy

2. Environmental conditions are favorable

Medical significance of bacterial endospores

1. Lockjaw, gas gangrene, anthrax, botulism

2. Control of spores

3. Disease connection: endospore infections

4. A note on terminology: spore and endospore

1. Unique characteristics

1. rRNA genetic sequence

2. Unique method of DNA compaction, membrane lipids, cell wall

Metabolic adaptation

1. Survive environments of intense heat, salt, acid, pH, pressure

2. Extremophiles: methanogens, halophiles, psychrophiles, thermophiles

Bergey's Manual of Determinative Bacteriology

A historical bacterial classification system based strictly on phenotypic, observable characteristics like shape, arrangement, and staining responses.

Bergey's Manual of Systematic Bacteriology

A bacterial classification system combining phenotypic traits with ribosomal RNA (rRNA) sequence analysis to establish genetic relationships.

1. Gracilicutes: gram-negative cell walls, thin-skinned

   • Firmicutes: gram-positive cell walls, thick and strong

   • Tenericutes: lack a cell wall, soft

   • Mendosicutes: archaea

1. Diagnostic scheme

1. Phenotypic method of classification

2. Gram-positive and gram-negative, cell walls, cell shape, arrangement, aerobic and anaerobic

Species and subspecies in bacteria and archaea

1. Strain, subspecies, or type

2. Serotype: distinct antibody response