Chapters 1 & 4 Flashcards
Coccus
Possible shape of a bacterial cell. Plural: cocci; berry-shaped
Bacillus
Possible shape of a bacterial cell. Plural: bacilli; little rods or walking sticks
Spiral
Possible shape of a bacterial cell
Diplococci
Cocci that remain in pairs after dividing
Streptococci
Cocci that divide and remain attached in chainlike patterns
Tetrads
Bacterial shape; Bacterial cells that divide in two planes and remain in groups of four
Sarcinae
Bacteria cell shape; Those that divide in three planes and remain attached in cublike groups of eight
Single bacilli: single rod like bacteria cell
Diplobacilli
Vibrios
Bacteria cells that look like curved rods
Spirilla
Singular: Spirillum
Spirochetes
Group of spiral shaped bacteria cells
Monomorphic
In relation to bacteria, this means that the cell maintains a single shape. Generally true unless there are environmental factors that cause their shapes to alter. If the shape is altered the identification becomes difficult. Some bacteria cells are genetically pleomorphic which means they can have many shapes, not just one.
Pleomorphic
Bacteria that cells are genetically pleomorphic, which means they can have many shapes, not just one.
Glycocalyx
General term for substances that surround cells; Bacterial glycocalyx is a viscous (sticky), gelatinous polymer that is external to the cell wall and composed of polysaccharide, polypeptide, or both. Varied composition throughout species, but mostly secretes from the cell to the cell surface. If the substance is organized and firmly attached to the cell wall the glycocalyx is described as a capsule. Presence of a capsule is determined by negative staining. If the substance is unorganized and only loosely attached to the cell wall the glycolayx is described as a slime layer.
Extracellular Polymeric Substances (EPS)
The glycocalyx is a very important component of biofilms. A glycocalyx that helps cells in a biofilm attached to their target environment and to each other. It protects the cells within it, facillitates communication aomong them, and enables the cells to survive by attaching to various surfaces in their natural environment.
Flagella
Not to be confused with phalanges which can overturn a commercial airplane’s engine (Source: Phoebe Buffet). Flagella are long filamentous appendages that propel bacteria.
Atrichous/Peritrichous/Polar/Monotrichous/Lophotrichous/Amphitrichous
Different possibilities for Flagella locations on bacterial cell.
Atrichous: No flagella
Peritrichouse: All over flagella
Monotrichous: One flagella at one end
Lophotrichous: tuft of flagella at one end
Amphitrichous: One larger flagella at each end
Three basic parts of flagella
- Filament: the long outermost region, constant in diameter and contains the globular; contains protein flagellin arranged in several chains that intertwine and form a helix around a hollow core
- Basal body: Anchors the flagellum to the cell wall and plasma menbrane; composed of small central rod inserted into a series of rings. Gram-negative bacteria contain two pairs of rings; the outer pair of rings is anchored to various portions of the cell wall and the inner pair of rings is anchored to the plasma membrane. In gram-positive bacteria only the inner pair is present.
- The hook at which the flagella attaches to the bacteria cell
Motility
The ability of a cell/organism to move by itself; helped by flagella
Taxis
Benefit of flagella is that bacteria is able to move toward a favorable environment or away from a particular stimulus; this movement is called taxis.
Chemotaxis: In response to chemical stimuli from the falgella a bacteria cell can determine if the chemotactic signal is positive (called an attractant) the bacteria move toward the stimulus; if negative (called a repellent) the bacteria move away
Phototaxis: a bacteria’s movement away from light stimuli
Axial Filaments
Given spriochetes particular spiral, intertwined cells, they move by the means of axial filaments (also called endoflagella) which are bundles of fibrils that arise at the ends of the cell beneath an outer sheath and spiral around the cell
https://vimeo.com/53465803
Fimbriae
Singular: fimbria;
Subtype of pilin, a protein arranged helically in shorter lengths compared to flagella on the outside of a bacterial cell. Can occur at the poles or be evenly distributed across the cell. Fimbriae have a tendency to stick to each other and to surfaces - as a result they are involved in forming biofilms and other aggregations on the surfaces of liquids, glass, and rocks. Fimbriae help attach bacteria cells to epithelial surfaces in the body
Pili
Subtype of pilin, a protein arranged helically in shorter lengths compared to flagella on the outside of a bacterial cell.
Usually longer than fimbriae; involved in motility and DNA transfer. One type of motility, twitching, a pilus extends by the addition of subunits of pilin, makes contact with a surface or another cell, and then retracts (power-stroke) results in short jerky intermittent movements.
Another type of motility associated with pili is gliding motility which is the smooth gliding movement of myxobacteria, some utilize pilis retraction.
Conjugation pili: pili used to bring bacteria together allowing the transfer of DNA from one cell to another. This can include a bacteria cell with or without the same DNA makeup. In this process one bacterium called an F+ cell connects to receptors on the surface of another bacterium of its own species or a different species. The F+ cell is added to the other cell and the exchanged DNA can add a new function to the recipient cell, such as antibiotic resistance or the agility to digest its medium more efficiently
Cell Wall
A complex, semirigid structure responsible for the shape of the cell. Almost all prokaryotes have a cell wall that surrounds the underlying, fragile plasma (cytoplasmic) membrane and it protects it and the interior of the cell from adverse changes in the outside environment
Major function: prevent bacterial cells from rupturing when the water pressure inside the cell is greater than that outside the cell ; Helps maintain shape of bacterium and serves as a point of anchorage for flagella.
It should be noted that the cells of some eukaryotes, ncluding plants, algae, and fungi, have cell walls, their walls differ chemically from those prokaryotes, are simpler in structure, and are less rigid
Peptidoglycan
Macromolecular network that composes a bacterial wall; present alone or with other substances. Consists of a repeating disaccharide connected by polypeptides to form a lattice that surrounds and protects the entire cell. Made up of disaccharides which are made up of NAG and NAM that line up in chains and are connected to polypeptides ; structure of polypeptide link varies but always include tetrapeptide side chains;
Penicillin interferes with the final linking of the peptidoglycan rows by peptide cross-bridges. resulting in the cell wall becoming greatly weakened and the cell undergoes lysis (destruction caused by rupture of the plasma memrane and the loss of cytoplasm)
Microorganisms
Organisms that are too small to be seen with the unaided eye; includes bacteria, archaea, fungi, protozoa, microscopic algae, and viruses
Benefits of microbes in our lives
- Decompose organic waste
- Generate oxygen by photosynthesis
- Produce chemical products such as ethanol, acetone, and vitamins
- Produce products used in manufacturing (e.g. cellulase) and disease treatment (e.g. insulin)
How many microorganisms are pathogenic?
Only a small portion
Knowledge of microorganisms allows humans to…
- Prevent food spoilage
- Prevent disease
- Understand causes and transmission of disease to prevent epidemics
