Presentation on theme: "And Bacterial Creepers I study the lives on a leaf:the little Sleepers, numb nudgers in cold dimensions Beetles in caves, newts, stone-deaf fishes, Lice."— Presentation transcript:
And Bacterial Creepers I study the lives on a leaf:the little Sleepers, numb nudgers in cold dimensions Beetles in caves, newts, stone-deaf fishes, Lice tethered to long limp subterranean weeds, Squirmers in bogs, And bacterial creepers Theodore Roethke
The Bacteria §Phylum: Schizomycetes §Cells are prokaryotic and amongst the smallest known cells ( length µm ). §No membrane bound nucleus. §Have ribosomes,but no other organelles. §DNA present as a long circular molecule. §( see handout for bacterial structure)
Habitat §Bacteria are found everywhere. §Air §Water §Soil §On plants and animals. §In plants and animals.
Types of Bacteria §There are three major groups of bacteria based on their shapes; coccus, bacillus, and spirillum.
2.Bacillus §Plural is bacilli. §A rod - shaped bacterium. §Exists as single cells, in pairs (diplobacilli), and in chains (streptobacilli).
3. Spirillum §Plural is spirilli. §A spiral - shaped bacterium. §Exist only as single cells.
Bacterial Structure §Cell Wall - outermost structure of the cell. §Made up of a substance called peptidoglycan ( a long chain of sugars linked to amino acids ). §Penicillin destroys bacteria by interfering with the peptidoglycan molecules.
Bacterial Structure Continued §Cell Membrane - Found beneath the cell wall. §May be folded inward. §ATP production (energy), takes place on the folds of the membrane.
Bacterial Structure Continued §Capsule: This is a layer of slime secreted over the cell wall of the bacterium. §The capsule provides protection for the bacterium. §Bacteria that have capsules are said to be encapsulated. §Most pathogenic bacteria are encapsulated.
Bacterial Structure Continued §Flagella - Some bacteria in the bacilli and spirilli categories can move by way of flagella ( whip - like structures that propel the bacteria). §Note: Cocci do not have flagella.
Bacterial Physiology-O 2 Needs §Some bacteria need O 2 and others do not. §Aerobic Bacteria: Need O 2 for cellular respiration. §Facultative Anaerobes: Can live in the presence or absence of O 2. §Obligate Anaerobes: Can live in the absence of. O 2 only. An example is Clostridium.
Bacterial Physiology-Nutritional Needs §Like all living things bacteria need food. §Bacteria are placed in one of two categories, depending on how they get their food. §The two categories are: Heterotrophic bacteria and Autotrophic bacteria.
Heterotrophic Bacteria §Heterotrophs must get their food from a source of pre- formed organic matter: §(A) Saprobes- feed on the remains of dead plants and animals. §(B) Parasites - live on or in the organism and cause disease. For example, Mycobacterium tuberculosis.
Autotrophic Bacteria §Autotrophs can make their own food: §Photosynthetic-use a special type of chlorophyll called bacteriochlorophyll. §O 2 is not released in bacterial photosynthesis §Chemosynthetic -obtain energy by breaking down inorganic material such as iron or sulfur.
Bacterial Physiology- Reproduction §The growth of bacteria is limited by the following factors: è temperature è pH è moisture content è nutrient availability è competition from other organisms
Bacterial Physiology- Reproduction continued §Bacteria reproduce asexually by binary fission. Using this process bacteria reproduce about every 20 minutes.
Bacterial Physiology- Reproduction continued §The rate of reproduction can be plotted in a graph called a Growth Curve. §Under ideal conditions one bacterial cell can produce a mass of 2 million Kg in 24 hours. §In reality this never happens. Why?