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.
