L1b. Bacterial Anatomy Flashcards
Bacillus
usually straight rods
Cocci
Usually spherical but can be oval or elongated.
When they divide, the cells can remain attached to one another
Diplococci
cocci that remain attached in pairs
Streptococci
Cocci that remain attached in chains
Tetrads
Cocci that remian attached in groups of four
Sarcinae
Cocci that remain attached in groups of eight
Staphylococci
Cocci that are in clusters
Coccobacilli
Bacilli that have curved ends and closely resemble cocci
Vibrios
Bacilli that have one curve or twist. They are usually coma shaped
Helicobacter
long rods with a few twists.
Spiral
these are rods shaped with multiple twists.
Cell envelope
cytoplasmic membrane and cell wall.
inner membrane, thin layer that encloses the cytoplasm of the cell.
composed primarily of phospholipids and proteins.
Bacterial cytoplasmic membranes do not contain sterols like cholesterol.
Cell Wall
is outside the cytoplasmic membrane and protects the interior of the cell from adverse changes in the outside environment.
Complex, semi-rigid structure responsible for shape.
Determines the gram reaction (+ or -)
Contributes to the ability of some species to cause disease, site of action of some antibiotics.
Composed of Peptidoglycan
Peptidoglycan
“murein”
consists of repeating disaccharide attached to a polypeptide to form a lattice. The disaccharide portion is made up of nomosaccharides called N-acetylclucosamine (NAG) and N-acetylmuramic acid (NAM) linked by B-1,4 glycosidic linkage.
Adjacent rows are linked by a tetrapeptide (4 amino acids)
Cell walls of Gram Positive Bacteria
cell wamm consists of a thick peptidoglycan (20-80nm) with multiple layers. This makes the cell envelope a two layered structure.
Cell walls of Gram Negative Bacteria
cell wall consits of a thin peptidoglycan layer. usually one or a few (2-4nm). Also have an Outer Membrane
Lipoteichonic Acid
Macromolecule in the cell wall of Gram Positve Bacteria. Spans the peptidoglycan layer and is linked to the cytoplasmic membrane.
Cell wall teichoic acid
linked ot ehe peptidoglycan.
Outer Membrane
consists of proteins, phospholipids, and lipopolysaccharides. Provides structural rigidity in place of a thicker peptidoglycan layer.
Attached to the peptidoglycan via lipoprotiens.
Lipopolysaccharide
Toxicity to mammalian cells, (endotoxin)
Cytoplasm
substance of the cell enclosed within the cytoplasmic membrane.
80% water, and is composed primarily of proteins, carbohydrates, lipids, inorganic ions, and low molecular weight compounds.
Thick, aqueous, semitransparent, and elastic.
Major structures: nuclear material, ribosomes mesosomes inclusions spores
Nuclear Material
is called nucleoid
contains a single, long, tightly coilded, circular double stranded DNA.
Does NOT include histones, and are NOT surrounded by a nuclear membrane.
May contain small circular double stranded DNA molecules called Plasmids
Ribosomes
appear as granules that give the cytoplasm a granular appearance. Function as the site of protein synthesis
Composed of two subunits, each subunit contains a protein and a type of RNA. Bacterial Ribosomes are called 70s ribosemes.
Several antibiotics exert their actions on riboseome to inhibit protein synthesis.
Mesosomes
NOT observed in Gram Negative bacteria. Folds of cell memebrane, they function in cell division. They are the point of attachement for DNA to begin duplicaiton, and play a role in septum formation during cell division
Inclusions (Storage Granules)
Reserve deposits, where the cell stores certain nutrients whey they are plentiful and use them when needed.
Spores (Endospores)
Cytoplasmic structures in Gram Positive bacteria that are dehydrated, highly durable, resistant, and dormant. When released into the environment they can survive for a long time and resist extreme heat, lack of water, chemicals, radiation, etc.
Gram Negative species also form spore like structures that resist heat and chemicals.
Sporulation (Sporogenesis)
the process of spore formation within a cell. The process begins whenever the key nutrient is depleted or deficient.
Germination
the process of spores becoming vegetative cells.
Biofilms
Groups of cells become embedded in a common matirix composed fo polysaccharides. Bacterial cells within biofilms are physiologically different from their corresponding free counterparts. Function in a coordinated matter as consortia (may mimic behavior of multicellular organisms)
Formation occurs in 4 distinct stages:
initiation, maturation, maintenance, dissolution
Flagella
long (15-20 micrometers) filamentous appendages attached inside the cytoplasmic membrane and free at the other end. Confer motility to organisms
Composed of a protein called Flagellin (flagellar antigen is H)
Fimbriae/Pili
Hair-like appendages that are shorter, thinner and straighter than flagella. Used for attachment. Composed of Pilin.
Can have a Sex Pilus, is used to join two bacteria cells and transfer DNA.
