Kingdoms Archaebacteria and Kingdom Eubacteria General Prokaryotes are
Kingdoms Archaebacteria and Kingdom Eubacteria
General • Prokaryotes are single-celled organisms. They are the smallest, simplest organisms.
Kingdom Archaebacteria • Found in anaerobic (no oxygen) and extreme conditions • high [salt], high temperature, low p. H • believed to be the conditions on the early earth • earth’s early atmosphere did not contain oxygen
Kingdom Eubacteria • • includes common bacteria largest of the two bacteria kingdoms Bacteria are either gram positive or gram negative Contain peptidoglycan in cell wall
• have a cell wall, a cell membrane surrounds the cell but no membranebound organelles or nucleus • are covered by a layer of “slime” called a capsule.
• They exist in three basic shapes: – Cocci – spherical – Bacilli - rod-shaped – Spirilla - spiral
• Some bacteria are able to move using special cell structures called cilia and flagella.
Respiration • Obligate aerobes must have oxygen. • Obligate anaerobes cannot survive in the presence of oxygen. • Facultative anaerobes will use oxygen if present but don’t need it.
Nutrition • Most are heterotrophs • Some are autotrophs – They either use chemicals as a source of energy (chemoautotrophs) or are photosynthetic (photoautotrophs).
Reproduction • Prokaryotes have a single circular chromosome attached to the inside of the plasma membrane. • Asexual reproduction – splitting in two in a process called binary fission. – The DNA is copied and the cell divides into two identical cells.
• Sexual reproduction – combines genes from two different bacteria to increase variation. – Three types of sexual reproduction in bacteria: 1. Conjugation 2. Transformation 3. transduction
1. Conjugation Two cells join briefly and one cell donates some DNA (called a plasmid) to the other one. Sometimes part of the cell’s chromosome is donated as well.
2. Transformation Bacteria can also pick up pieces of DNA from the environment. 3. Transduction sometimes viruses transfer pieces of DNA from one cell to another.
Bacteria and Disease • Bacteria that cause disease are known as pathogenic bacteria
Bacteria cause disease in one of two ways: Damage cells and tissues by breaking down the cells for food. For example, Mycobacterium tuberculosis destroys lung tissue.
Releasing toxins that interfere with the normal functioning of the host. For example, Corynebacterium diphtheriae releases toxins into the bloodstream where they cause breathing difficulty, heart failure, paralysis, and death.
Other Diseases Caused by Bacteria: • • • Tetanus Botulism Chlamydia Leprosy Necrotising Fasciitis (flesh eating disease) Salmonella Food Poisening
Control of Bacterial Growth • Disinfectants – Kill bacteria on surfaces, floors and non-living objects. – Usually chemicals such as alcohols, bleach, hydrogen peroxide or iodine • Antiseptics – Kill bacteria on the skin of humans or animals • Bactericidal – kill bacteria outright • Bacteriostatic – stop bacteria from growing or dividing but don’t kill them (often antibiotics are bacteriostatics)
• Natural Body Defenses: – Skin – Fever – White blood cells – Antibodies • Attacks the bacterium – Antitoxins • Attacks or neutralizes the toxin produced by the bacterium
– Vaccines • small doses of live bacteria, killed bacteria, or parts of bacterial cells which cause an immune response • if exposed to that bacterium again in the future, your immune system will launch a strong response to it. – Antibiotics • are compounds that interfere with the normal growth of bacteria.
Useful Bacteria • Decomposers (saprophytes) – Break down complex organic molecules into simpler substances – Used to our advantage in sewer treatment • Nitrogen Fixation – Take free nitrogen (N 2) and “fix” it into a form usable by plants (ex. Ammonia NH 4) – form symbiotic relationships with plants – release usable nitrogen compounds to plants
• Intestinal Bacteria – Form symbiotic relationships with animals – Bacteria get home and food and help animal digest complex carbohydrates and make important vitamins • “Clean-Up Teams” – Bacteria that digest petroleum products – Remove poisonous wastes from water • Manufacturers – Produce foods (cheese, yogurt, butter milk, sour cream, vinegar) – Synthesize drugs through genetic engineering • Insulin, Human Growth Hormone
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