Bacteriology Flashcards
Growth - processes of life
increase in size
Reproduction - processes of life
increase in number
Responsiveness - processes of life
ability to react to environmental stimuli
Metabolism - processes of life
organisms take in nutrient from outside themselves and use the nutrients in a series of controlled chemical reactions to provide the energy and structure needed to grow, reproduce, and respond.
Prokaryotes
They lack nucleus but can read DNA and make protein at the same time. They also lack various internal structures bound with phospholipid membranes. They are typically 100 times smaller. In addition, they include bacteria and archaea.
Eukaryotes
They have nucleus, is more complex, and is composed of algae, protozoa, fungi, animals, and plants.
Glycocalyces (“sweet cup”)
They are gelatinous, sticky substance surrounding the outside of the cell. It is also composed of polysaccharides, polypeptides, or even both.
Capsule (virulence factor) - Glycocalyces
They are protective structure outside the cell wall of the organism that secretes it and only certain bacteria can form capsules. The chemical composition of each capsule is unique to the strain of bacteria that secreted it.
It is composed of organized repeating units of organic chemicals, they firmly attach to the cell surface and prevent encapsulated bacteria from being recognized by host (phagocytosis).
Slime layer - Glycocalyces
They are loosely attaching themselves to the cell surface and thinner, are water-soluble, and the sticky layer allows prokaryotes to attach to surfaces.
Their job is to protect the cell against drying, traps nutrients and binds cells together, which is called biofilm.
Flagella
They are responsible for movement, have long structures that extend beyond cell surface, and are not present on all bacteria
Fimbriae (virulence factor)
They have sticky, bristle like projections, are used by bacteria to stick to one another and to substances in environment, are shorter than flagella, and also serve and important function in biofilms.
Pili
It is a special type of fimbriae and also known as conjugation pili, it is longer than fimbriae but shorter than flagella, bacteria typically have only or two per cell, and transfers DNA from one cell to another (conjugation).
Bacterial cell walls
They provide structure, shape, and protect cell from bursting when fluids flow into the cell by osmotic forces, assist some cells in attaching to other cells or in resisting antimicrobial drugs, can target cell wall of bacteria with antibiotics, and give bacterial cells characteristic shapes.
They are also composed of peptidoglycan, a mesh like complex polysaccharide. They also lie outside the cell membrane in nearly all bacteria.
Cocci
Spherical cells that appear singly or in chains (streptococci) or in
clusters (staphylococci) or in
cuboidal packets (sarcinae)
Bacilli
Rod-shaped cells
There can be single ones, diplobacilli-two, streptobacilli-in chains, palisade-almost side by side arrangement, and V-shaped bacilli
Coccobacillus
In between cocci and bacilli
Vibrio
Curved shaped rods
Spirillum
Stiff spiral shaped
Spirochete
Flexible spiral shaped
Pleomorphic
Star-shaped, triangular, and rectangular in shape
Diplococci
Cocci in pairs
Tetrads
Cocci divide in two perpendicular planes and remain attached
Structure of peptidoglycan
NAG and NAMs line up row after row, with tetrapeptide, a protein containing 4 amino acids. This tetrapeptide is what keeps the rows pulled apart by cross bridges.
Gram - Positive Bacterial Cell Walls
Has thick layer of peptidoglycan, contains unique chemicals called teichoic acids and lipoteichoic acids, appear purple in gram staining procedure.
Acid Fast Bacteria
It is found in Mycobacterium, composed of mainly of lipid.
Lipid component is the mycolic acid (waxy cell wall)
Fun fact, acid fast bacteria stain weakly gram positive because due to about 60% of mycolic acid (waxy cell wall). Mycolic acid actually helps the cells survive desiccation, or drying out, and therefore, makes it difficult to stain with regular water-based dyes.
Gram-Negative Bacterial Cell Walls
Has a thin layer of peptidoglycan, has bilayer membrane outside the peptidoglycan containing phospholipids, proteins and lipopolysaccharide (LPS). The LPS contains Lipid A (endotoxin) portion and may impede the treatment of disease. It also appears pink in Gram staining procedure.
Endotoxin
Endotoxin is only present in Gram negative cell walls only and released when the outer membrane disintegrates. The Lipid A of LPS can cause fever, vasodilation, inflammation, shock, and blood clotting.
Exotoxins
Produced both be Gram positive and negative bacteria. Target specific types of cell to destroy.
Cytotoxins - Exotoxins
kill host cells or affect their function
Neurotoxins - Exotoxins
specifically interfere with nerve cell function
Enterotoxins - Exotoxins
affect cells lining the gastrointestinal tract
Antibiotic Penicillin
Interferes the final stages of peptidoglycan synthesis
Bacteria without cell walls
They are often mistaken for viruses due to the small size and the lack of walls. They also have other features of prokaryotic cells such as ribosomes. Cell membrane contain sterol-like molecules, called hopanoids, which help stabilize the membrane.
Bacterial Cytoplasmic Membranes
Referred to as phospholipid bilayer and contains integral and peripheral proteins.
Osmosis
special name given to the diffusion of water across a semipermeable membrane. The semipermeable membrane allows water to come through, but not solutes
Isotonic solution
water on the outside equals on the inside
Hypertonic solution
there is more water on the outside than on the inside
Hypotonic solution
there is more water on the inside than on the outside
Group translocation
the substance is chemically altered during transport
Cytosol
liquid portion of the cytoplasm
Inclusion
deposits found within bacterial cytosol
Granules - Inclusions
not membrane bound and contain densely compacted substances (glycogen or polyphosphate)
Vesicles - Inclusions
specialized membrane-enclosed structures that contain gas or lipids
Nuclear region (Nucleoid)
centrally located consists of mainly DNA, but also RNA and protein
Plasmids - Nuclear region
extrachromosomal pieces of smaller, circular DNA. They are extra info for the bacteria
Ribosomes
They are nonmembraneous organelles of the cytoplasm of eukaryotes, where synthesizes protein. Prokaryotes (bacteria) have 70S ribosomes and Eukaryotes have 80S ribosomes.
Streptomycin and Erythromycin
they bind to 70S ribosomes and disrupt bacterial protein synthesis
Endospores
unique structures produced by some bacteria. Vegetative cells transform into endospores when multiple nutrients are limited and they are resistant to extreme conditions such as heat, radiation, chemicals
Facultative anaerobes
they can live w/ or w/o oxygen
Obligate anaerobes
Remember that obligates have to live inside a host. They also live in the intestinal tract w/o oxygen and be fine, however, if there are exposed to oxygen they can die, until they make an endospore. Once the endospores are formed than they are fine.
