Study Guide Sheet 1 (pt1) Flashcards
What is meant by “antigenic group”, and how are groups often designated?
Antigenic groups are for organisms possessing a major antigen that may be common to more than one species of the genus; usually designated by capital letters
What is meant by “antigenic type”, and how are types often designated?
Antigenic types are for organisms possessing a specific antigen that is common to only very limited, closely related organisms; usually designated by numbers
State and describe the major shapes of bacteria cells
- Coccus - spherical
- Bacillus – rod or cylindrical
Variations of Bacillus:
a) Coccobacillus – short, plump bacillus which resembles a coccus
b) Coryneform or Diphtheroid – club shaped; resembling diphtheria bacillus
c) Pleomorphic – a single organism or species having various distinct forms, e.g same organism being short and plump as well as long an slender, perhaps both in the same field of view - Spirochete or spirillum – spiral or corkscrew shape (very thin, poorly staining, not usually visible by the gram stain method)
State and describe the arrangements of bacteria cells
- Single – (by itself), no particular arrangement
- Pairs – division on one plane; daughter cells remain paired
- Clusters – division on three planes, (look like grapes)
- Palisades – “picket fence”, division on one plane perpendicular to the short axis of the chain (bacilli only)
- Chains – division on one plane, perpendicular to the long axis of the chain; cells remain attached “end-to-end”
What are the major components of the bacterial cytoplasm?
- Composition – thick, aqueous, elastic
- Cell sap (e.g. water, nutrients, storage granules, etc…)
- Genetic material and mechanisms (DNA, RNA, ribosomes 70S)
What are the major functions of the bacterial cytoplasm?
Metabolism and replication
What are the major components of the bacterial cytoplasmic membrane?
Composition (8 – 10% of dry weight of cell)
Phospholipid bilayer
Proteins: some function as porins and others as enzymes
What are the overall functions of the bacterial cytoplasmic membrane?
- Selective permeability
- Site of energy production
- Site of synthesis and transport of peptidoglycan, teichoic acids, and outer membrane componets
- Site of extracellular hydrolytic enzymes
What are the major overall functions of the bacterial cell wall?
- Shape and rigidity
- Provides protection from the environment and from some antimicrobic agents
- Site of antibody attachment to major cell antigens
What is the metabolically dormant, heat resistant structure within the cytoplasm of certain gram-positive bacteria?
The Endospore (Spore)
What is the Endospore’s function
To allow the cell to survive under adverse harsh environmental conditions (heat, chemicals, and irradiation), by going from a vegetative state to a dormant state.
What is the mucoid (slimy) material surrounding certain bacterial cells?
The capsule
What are the capsules functions?
- Resistant to phagocytosis
- May “hide” surface antigens
- Sometimes assists in attachment (dental plaque)
What are the thread-like structures on the exterior of bacteria cells and what are they composed of?
Fimbriae; composed of glycoprotein
What are the functions of Fimbraie?
Aid in facilitating bacterial attachment to appropriate cells
Those which lengthen and are involved in DNA transfer during conjugation, are called sex pili.
Describe the components and structure of the gram-positive cell wall, including details of peptidoglycan.
- Peptidoglycan (60 – 80%) with N-acetlyglucosamine and N-acetylmuramic acid
- Teichoic acids
- Protein inclusions
Describe the components and structure of the gram-negative cell wall.
Outer membrane – lipopolysaccharides (O-antigen and lipid A) , lipoprotein layer and phospholipid bilayer
Peptidoglycan (10 – 20%)
Cytoplasmic membrane – phospholipid bilayer
Which major cell bacteria is very thin, poorly staining, not usually visible by the gram stain method
Spirochete or spirillum
Which bacteria cell arrangement is for bacilli only?
Palisades
What are porins?
proteins that form channels through which large molecules can pass
What factor controls transport of most compounds entering and leaving the cell
Selective permeability
Spore may be viable for how long?
Years
In the peptidoglycan of gram positive cell bacteria, how are N-acetlyglucosamine and N-acetylmuramic acid linked?
They are cross-linked by short peptide chains.
What connects to the cytoplasmic membrane with long chain glycerol or ribitol connected with phospholipid bridges?
Teichoic acids
Protein inclusions are _____ frequent in gram-positives than in gram-negatives.
Less
