Lecture 2: Bacteriology Review Flashcards
Three things that prokaryotes and eukaryotes have in common
DNA, cell membrane, cytoplasm
Pathogenic bacteria tend to have a smaller genome because
Uses host genome to create needed proteins
In a light microscope/gram stain, gram + are
blue
In a light microscope/gram stain, gram - are
red
Staphylococci form
grapes
Streptococci form
chains
8 factors for evaluating colony appearance
Shape Margin Elevation Size Texture Appearance Pigmentation Optical property
Strain colony morphology depends on what four factors
Culture medium
Incubation time
Incubation conditions
Single gene functionality
Two things that bacterial cells lack
Cytoskeleton
Membrane-bound organelles
Cytoplasm
Jelly-like material that helps facilitate chemical reactions to dissolve solutes like carbs and proteins. Contains any cell organelles
Cytoplasm consists of an aqueous solution of three groups of molecules:
- Macromolecules such as proteins, mRNA, tRNA
- Small molecules that are energy sources, precursors of macromolecules, metabolites, or vitamins
- Various inorganic molecules that are required for enzymatic activity (co-factors)
Protein accounts for more than ___% of the dry weight of the cytoplasm
50
Nucleoid
-One large circular molecule of DNA
Nucleoid is composed of
- DNA (60%)
- Small amounts of RNA
- Small amount of protein
Nucleoid protein include
Transcription factors
Nucleoid-assisted proteins (NAPS)
Transcription factors
regulates the bacterial genome
NAPs
Carry out spatial organization of the nucleic acid
The number of proteins encoded by the bacterial chromosomes depends on
the species
Plasmid
Large circular molecule of double stranded DNA that replicates autonomously from the chromosome
Two categories of proteins encoded by plasmids
- Virulence factors: causes diseases
- Resistance genes: helps cell survive antibiotics and other toxic compounds
Each plasmid is present in the cell in a defined ___ _____ that is self-regulated by the plasmid
copy number
Conjugation
Transfer of plasmid from cell-cell
What can enter the cell through passive diffusion?
Small lipid soluble molecules
Purpose of the cell wall?
- Protects the cell from osmotic lysis
- Provides mechanical protection
What is the cell wall made of?
A polymer of disaccharides cross-linked by peptides, called peptidoglycan or murein
Gram positive bacteria cell wall?
thick layer of murein and techoic acids providing ridgidity
Gram negative bacteria cell wall?
Thin layer of murein, surrounded by the outer membrane which contains lipopolysaccharides (LPS or endotoxins), and porins
Porins
Proteins that allow diffusions of hydrophilic molecules into the periplasmic space
Capsule
A polysaccharide layer outside of the cell wall which confers a mucoid appearance to some bacterial cells
Capsule purpose
- Mediates attachment to particular surfaces
- Protects bacteria from engulfment by predatory protozoa/white blood cells (phagocytes)
- Protects from attack by antimicrobial agents
Three types of surface components
- Flagella
- Sex pilus
- Fimbriae
Flagella
Filamentous protein structures that allow the bacteria to swim/move
Fimbriae
Shorter and stiffer than flagella and are generally used for adherence to surfaces
Sex pilus
Used for conjugation in gram negative bacteria
Three main units of a flagella
- Filament
- Hook
- Basal body
Endospores
Dormant, highly resistant bodies that ensure survival during adverse environmental conditions
Sporulation
The process leading to spore formation
Germination
The process leading to the vegetative cycle
Two important types of bacteria that form spores
Bacillus
Chlostridium
