Prokaryotic Cells ch. 4
Methods in bacterial IDing
Morphology=shapes
Gram positive bacteria
Thick layer of peptidoglycan in their cell walls. Stains purple.
Atypical cell walls
-Some bacteria have walls with lipids: very wary. Resistant to chemicals and dyed in gram staining. -some bacteria have no cell walls.
Glycocalyx
2 types: slime layer and capsule
Bacteria with flagella can move in response to
A chemical signal
Fimbriae
Allows bacteria to attach to things. Ashort, bristle-like fibers that spout off of many bacteria.
Inclusions
Storage shacks for nutrients.
Prokaryotic cells with peptidoglycan in their cell walls
Bacteria
Endotoxins and gram negative bacteria
Cause fever and shock reactions in the host.
All bacteria have
Cell membrane, cytoplasm, ribosomes, one chromosome
Most bacteria have
Cell wall and surface coating
Species
Collection of bacterial cells that share a similar pattern of traits. Members of a species can show variation(ex: structure, metabolism). Called strain or subspecies. Bacteria strain have same parents, change over time.
Granules
Contain inorganic compounds. Type of inclusion.
Cell membrane encased by
Cytoplasm, a dense, gelatinous solution.
Spore production
Depletion of nutrients and/or high temps. Cause bacteria to produce endospore.
Cell wall
Determines shape of cell. Structural support.
Bacterial endosposre
Dormant bodies that are produced by gram positive bacteria. Vegetative cell phase. Spore production. Survive in extreme heats, and conditions.
How can bacterial endospore survive in a high temp.?
Endospores contain high levels of calcium. Calcium removes water from endospore. This makes it less sensitive to heat.
Classification systems
Established in order to keep track of organisms.
Physiological/biochemical charcteristics
Ex: presence/absence of enzyme. Ex: oxidase decarboxylases
Some bacteria have
Flagella Pili Fimbriae Capsules Slime layers Granules
Peritrichous
Flagella all around cell. See slide for pictures
Polar arrangement(3 types)
Flagella at either one or both ends. Monotrichous, lophotricious, amphitrichous. See slide for pictures.
Pili and fimbriae
For attachment
Flagella
For movement
Capsules
For protection
Cell membranes have ability to
Form mesosomes (increases surface area for activities). See more often in gram positive bacteria.
Peri plastic Flagella(axial filaments)
Found on spirochetes. Consist of foiled threads which provide a wriggle-like movement.
Structure of cell wall
Functions: structure and shape Rigid
Gram + vs gram -
Gram negative bacteria are harder to kill than gram positive bacteria because of outer membrane. Drug treatments: some kill both. Some kill just positive or negative.
Cell wall separates out
Gram positive and gram negative bacteria
Toxic proteins and
Gram positive bacteria.
What happens to bacterial proteins of no endosposre?
If there is no endospore, heat will cause the protein to denature and the bacteria will die.
Prokaryotic cells location
In bacteria and archaea
Eukaryotic Cells location
In fungi, protozoa, algae, plants, and animals
Membrane-bound organelles
Internal cellular structures that carry out a particular function
A pilus
Involved in mating in which there is a partial DNA transfer from one cell to another. Ielongate, rigid tubular-like structure, composed of pilin
3 classification systems
Most important: a system that groups medically important bacteria according to morphological and physiological features.
Chemotaxis
Movement towards or away from a chemical signal
Negative chemotaxis
Moving away from an unfavorable stimulus. Ex: bacteria away from antibiotics.
Positive chemotaxis
Moving towards a favorable stimulus. Ex: bacteria towards food.
Plasmids
Nonessential pieces of DNA. Circular in shape. Can be free or integrated into chromosomes.
Why are plasmids interesting?
Not needed for bacterial survival. However, can be passed onto offspring. Plasmids carry traits. Ex: antibiotic-resistance can be modified and make cell do what we want.
Eukaryotic cells have
Nucleus and other membrane-bound organelles
Prokaryotic cells DO NOT have
Nucleus or other membrane-bound organelles
Classification based on medical microbiology
Only classifies bacteria that cause disease. Depends less on nomenclature, more on morphology, Divides bacteria into gram positive, gram negative, those without cell walls, and then subgroup them with respect to cell shape, arrangement, and physiological traits like oxygen use.
Slowest cells
Peritrichous rods. Ex: E. Coli is slow
Granules
Pockets that hold items or elements
Fastest cells
Polar flagellated cells
Slime layers
Prevent dehydration/water loss
Capsule
Protects bacteria from white blood cells. Ex: streptococcus pneumoniae more resistant against immune system
Slime layer
Protects cell from water and nutrient loss.
Flagella
Provide motility Has helical structure composed of numerous proteins Filament:a helical structure composed of proteins, and it is inserted in the hook. Hook(sheath): attached to cell by the basal body Basal body: stack of rings anchored through the cell wall to the cell membrane
Cell envelope
Provides protection Is a chemically complex eternal covering that is situated outside the cytoplasm. Layers: Glycocalyx, cell wall, cell membrane
Cell membrane functions
Reactions occur ATP Regulation
Cell membrane
Regulates what comes in and out of the cell. ATP is made at cell membrane (eukaryotic cells: ATP made in mitochondria)
What does cytoplasm contain?
Ribosomes Granules A ton more stuff
Both prokaryotic and eukaryotic cells have
Ribosomes, where proteins are made
Structured of bacteria
See chart on slide
Cytoplasm functions
Serves as a cell solvent for a variety of substances including sugar, amino acids, and salts.
Bacterial chromosomes
Singular strand of DNA. No nucleus. Nucleoid. Long segment of DNA that is coiled into a ball(needs to fit into bacteria cell)
Ribosomes function
Site of protein synthesis. Can freely floating the cytoplasm or attach to cell membrane. Consists of rRNA.
Type of arrangement determines ?
Speed of bacteria cell
Gram negative bacteria
Thin layer of peptidoglycan in their cell walls. Also, have outer membrane in cell wall. Stain pink/red.
Cell membrane structure
Thin, flexible sheet that surrounds the cytoplasm. Lipid belayer with embedded proteins.
Chemical analysis
Uses chemical structures to identify bacteria
Macroscopic morphology
Uses morphology on macroscopic level to identify bacteria. Ex: colors/edges of bacteria(smooth or rough)
Microscopic morphology
Uses morphology on microscopic level to identify bacteria. Gram staining.
Serological analysis
Uses surface markers called antigens on bacteria to id bacteria
Genetic and molecular analysis
Using genetic material to ID bacteria. Some bacteria have more G and C pairs than A and T pairs.