1. Introduction to Bacteriology Flashcards
Prokaryote
Prokaryotes are organisms whose cells lack a nucleus and other organelles. Prokaryotes are divided into two distinct groups: the bacteria and the archaea.
Eukaryote
Eukaryotes are organisms whose cells contain a nucleus and other membrane-bound organelles. There is a wide range of eukaryotic organisms, including all animals, plants, fungi, and protists, as well as most algae.
Bacterial components
- Glycocalyx
- Flagella
- Pili/Fimbriae
- Cell wall
- Cell Membrane
- Cytoplasm
- Nucleoid
- Plasmid
- Ribosomes
- Inclusions
Glycocalyx
- Substance that surround cells
- If organized and firmly attached to the cell wall = capsule
- If unorganized and loosely attached to the cell wall = slime layer
- Important component of biofilm (helps cell to attach to various
surfaces and to each other)
Flagella
Long filamentous appendages for movement of bacteria
Types of flagella
- Peritrichous (distributed over entire cell)
e.g. Escherichia coli - Monotrichous and polar (a single flagellum at one poles or
ends of the cell)
e.g. Vibrio cholerae - Lophotrichous and polar (a tuft of flagella coming from one
pole)
e.g. Helicobacter pylori - Amphitrichous and polar (at both pole of the cell)
e.g. Campylobacter jejuni
Pili / Fimbriae
- Hairlike appendages – shorter, straighter, thinner than flagella
- Fimbriae:
#occur at the poles or evenly distributed over the entire surface of the cell
#a few to several hundred per cell - Pili:
#Longer than fimbriae
#One or two per cell
Cell wall
- Complex and semi-rigid structure
- Determine the shape of bacteria
Cell (cytoplasmic) membrane
- Contains phospholipids
- Enclosing the cytoplasm
Cytoplasm
- Contain 80% water and primarily protein, carbohydrates, lipids, inorganic ions and low-molecular-weight compounds
Nucleoid
- Chromosomal DNA is located
Plasmid
- Small, circular, supercoiled, double-stranded DNA
- Extrachromosomal genetic elements, not connected to bacterial
chromosome
Ribosomes
-A ribosome is an intercellular structure made of both RNA and protein, and it is the site of protein synthesis in the cell
Ribosomes
-A ribosome is an intercellular structure made of both RNA and protein, and it is the site of protein synthesis in the cell
Inclusions
- found in bacteria as particles of aggregated protein
- represent sites of viral multiplication in a bacterium or a
eukaryotic cell and usually consist of viral capsid proteins.
The formation of endospore
- DNA is replicated
- Cellular division of cytoplasmic membrane
- Prespore formation begins
- Cortex formation
- Spore coat formation begins
- Maturation begins Exosporium formation
- Mother spore releases mature spore (endospore)
Shape of bacterial
- Coccus
- Bacillus/ Rod
- Spiral
Arrangement of cocci bacteria
- Diplococci
- Streptococci
- Tetrad
- Sarcinae
- Staphylococci
Arrangement of Bacillus/ Rod Bacteria
- Single Bacilli
- Diplobacilli
- Streptobacilli
- Coccobacilli
Arrangement of Spiral Bacteria
- Vibrio (curved rod)
- Spirilum (helical)
- Spirochete (helical and flexible)
Gram-Positive Cell Wall
- thick layers of peptidoglycan = form thick & rigid structure
- Prominent component = teichoic acids
- X outer membrane, lipopolysaccharide, porin proteins, periplasm
Functions of teichoic acid
- Bind and regulate movement of cations
- Prevent extensive wall breakdown and cell lysis
- Provide antigenic specificity (to identify gram +ve bacteria)
Gram-Negative cell wall
- thin layers of peptidoglycan & an outer membrane
- X teichoic acids
- has outer membrane, lipopolysaccharide, porin proteins & periplasm
Types of staining
- Simple staining
- Differential staining
- Special staining
