Microbio: Module 2 - Bacterial Structures

Bacillus is rod shaped, coccus is spherical, spirilla is a rigid helix or wavy, spirochete is a flexible helix, and vibrio is curved

Distinguish between the various shapes and arrangements of bacterial cells

Gram positive has a thick peptidoglycan layer, stains purple, contains teichoic acids, no outer membranes, and is sensitive to penicillin; Gram negative has a thin peptidoglycan layer, stains pink/red, contains lipopolysaccharides, contains two membranes, and is not sensitive to penecillin

Compare and contrast Gram positive vs. Gram negative bacteria

Bacillus

Rod-shaped

Coccus

Spherical

Spiral

Rigid helix or wavy

Spirochete

Flexible helix

Vibrio

Curved or comma shaped

capsule, cell wall, cell (outer) membrane

The bacterial envelope consists of the ______, _______, ______ _______

external

The envelope is ____ to cytoplasm

Plasma Membrane

Selectively permeable, has a phospholipid bilayer where there are hydrophilic heads and hydrophobic tails

Capsule

Can be easily removed by treating a culture with appropriate enzymes or by manipulating the presence of nutrients in the culture; is not integral to the life of the cell; the presence of one promotes virulence (the capacity to produce disease); also the presence of one interferes with phagocytosis

Gram Positive

Has a thick peptidoglycan layer, stains purple, contains teichoic acids but not lipopolysaccharide (LPS), no outer membrane, and is sensitive to penicillin (mostly)

Gram positive

Which contains teichoic acids? Gram positive or gram negative?

Gram positive

Which does not have an outer membrane? Gram positive or gram negative?

Gram positive

Which stains purple? Gram positive or gram negative?

Gram Negative

Thin peptidoglycan layer, stain pink/red, contains lipopolysaccharides but not teichoic acids, contains two membranes, and is not sensitive to penicillin

Gram negative

Which has a thin peptidoglycan layer? Gram positive or gram negative?

Gram negative

Which stains pink? Gram positive or gram negative?

Gram negative

Which contains lipopolysaccharides? Gram positive or gram negative?

Gram positive

Which is sensitive to penicillin (mostly)? Gram positive or gram negative?

Cytoplasm

All of cell’s contents enclosed within plasma membrane; is the part of the cell enclosed within the plasma membrane and within it are numerous cellular constituents that function in cell growth and replication

Nucleoid

Region of cytoplasm containing chromosomal DNA; DNA rich area and is not defined by a membrane

Binary Fission

Bacteria replicate their DNA and divide by process of this

Plasmids

Small, circular, independently replicating pieces of dsDNA that are found in the cytoplasm of some bacteria and are independent of the chromosomal DNA

Endospore

Extremely hardy structures that are highly resistant to heat, drying, radiation, and a variety of chemical compounds

Flagella

Confer motility (movement), aids in chemotaxis, and has many arrangements (single, polar, bipolar, dispersed)

Chemotaxis

Movement towards attractant or away from repellant

Pilli

Shorter, straighter, and thinner than flagella; function is adhesion to anchor for colonization of host cells and other surfaces; transmission of DNA by forming a bridge between donor and recipient bacterial cells

Colony

Visible masses of bacterial cells growing on an agar surface of solid bacteriological media, each presumably derived from a single cell or clone

Antigens

Components of microbes, usually protein structures, that are recognized as foreign by immune system and are targeted for destruction

Identify bacterial pathogens

What are metabolic tests used for?

To name bacteria, Genus should be capitalized and species should be lowercase and both must be italicized

Describe the correct way to name a bacterial species. What two taxonomical ranks are used and how are they written?

Capsule (slime layer), cell wall, and plasma membrane

What is the structure of the cell envelope?

Promote virulence

What is the function of the capsule for the cell envelope?

Confers structure and shape; provides tensile strength

What is the function of the cell wall for the cell envelope?

Controls selectively permeable movement of molecules into and out of the bacterium

What is the function of the plasma membrane for the cell envelope?

Nucleoid, plasmids, endospores, ribosome, chromosome, inclusion bodies

What is the structure of the cytoplasm?

DNA rich area not enclosed by a membrane

What is the function of the nucleoid in the cytoplasm?

Confers properties such as antibiotic resistance; encodes limited number of genes; expand genetic capability of host cell; transferable from donor to recipient bacteria

What is the function of plasmids in the cytoplasm?

Confers extreme resistance to environmental factors

What is the function of endospores in the cytoplasm?

Determinant of genetic traits

What is the function of chromosomes in the cytoplasm?

Double stranded DNA and is one or more circular or linear chromosomes

What is the structure of nucleoid?

Small and circular

What is the structure of plasmids?

Adhesion as an anchor for colonization of host cells and other surfaces and transmission of DNA via sex pilus by forming a bridge between donor and recipient bacterial cells

What is the function of pili?

Used for motility and aids in chemotaxis

What is the function of flagella?

Long, hollow, filament made of subunits called flagellin

What is the structure of flagella?

Prokaryotic ribosomes are present in the cytoplasm and are smaller than eukaryotic ribosomes; eukaryotic ribosomes are free in the cytoplasm and are present on the endoplasmic reticulum

Summarize the key differences between prokaryotic and eukaryotic ribosomes