bacteria 19-1 qcn92mbwxd4 (bacteria introduction) qcn92mbwxd4
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Bacteria19-1
https://www.youtube.com/watch?v=qCn92mbWxd4
(bacteria introduction)
Two Kingdoms
• Bacteria are divided into two separate kingdoms.– Archaebacteria
• Able to live in very extreme environments.• Lack peptidoglycan in their cell walls• Different membrane lipids• DNA sequences are more like eukaryotes than eubacteria
– Eubacteria• Represents all other bacterial cell and makes up most of the
prokaryotic cells on the planet.• Contains peptodoglycan in their cell walls
Classification of Archaebacteria
• Classified based upon the environment in which they are able to live.– Thermophiles
• Able to tolerate very high temperatures (60-100)– Able to live in hot springs or deep sea vents
– Halophiles • Able to tolerate very salty conditions.
– Great Salt Lake, Dead Sea
– Methanogens • Live in anaerobic environments, such as swamps.• Produce methane as a result of their metabolic processes.
Classification of Eubacteria
• Classification based upon their means of nutrient obtainment(…..how they eat.)– Photoautotrophs– Chemoautotrophs– Heterotrophs– Photoheterotrophs
Basic Characteristics
• “Ubiquitous”- they are everywhere• Prokaryotic
– Single celled; lacking a nucleus
• Genetic Material Circular – chromosome attached to a cell wall– Plasmids
• Circular piece of DNA that replicates during conjugation.
• Cell Wall• Reproduction occurs via binary fission
– Little to no genetic variation unless conjugation takes place
• Great metabolic diversity – https://www.youtube.com/watch?v=vAR47-g6tlA (archaea,
bacteria, and protist background – 12 min)
Two Types of Cell Wall Structures
• Gram positive -- Has one cell wall outside of plasma membrane and stains purple in a Gram stain.
• Gram Negative— has an additional membrane layer beyond the peptidoglycan and stains pink in a Gram stain.
Gram Positive Stain Gram Negative Stain
Shapes of Bacterial Cells
• Bacteria can be divided up into three main shapes.– Bacillus (rod shaped)– Coccus (sphere shaped)– Spirillum (spiral shaped)
Bacillus
Coccus
Spirillum
Movement of Bacteria
• https://www.youtube.com/watch?v=6p9e0oolbmE (shapes and movement – 3 min)
Bacterial Prefixes
• Prefixes can also be attached to the beginning of a shape to add further description– Diplo- = pairs– Strepto- = chains– Stapylo- = groups\ clusters
Diplococcus Streptococcus
Stapylococcus
Bacterial Reproduction
• Bacteria usually reproduce via binary fission.– Everything inside is copied
and the cell spits in two.
• Bacteria can also undergo conjugation where genetic information is exchanged between two organisms.
Releasing Energy
• Bacteria can undergo cellular respiration and fermentation
• Bacteria can be– Obligate aerobes– Obligate anaerobes– Facultative anaerobes
Endospores
• When conditions become unfavorable, many bacteria form an endospore to survive harsh conditions that might otherwise kill them.
Notes on 19-2
• Bacteria are vital to maintaining the living world.
• Some are producers that capture energy by photosynthesis
• Others help break down the nutrients in dead matter and the atmosphere allowing other organisms to use the nutrients
Decomposers
• Why are decomposers essential to all living things?
• Can recycle dead organisms as well as human waste, organic garbage, chemical waste.
• This process purifies the water and releases nitrogen and carbon dioxide gases, and leftover products that can be used as fertilizers.
Nitrogen Fixers
• Plants and animals depend on bacteria for nitrogen.
• Plants need nitrogen to make amino acids, which are the building blocks of proteins that both plants and animals need.
• Nitrogen must be converted from atmospheric nitrogen into a form plants can use.
• Most plants have a symbiotic relationship with nitrogen-fixing bacteria (Rhizobium)
Bacteria and Disease
• Bacteria cause disease in one of two general ways.– 1. damage the tissues of the infected
organism directly breaking them down for food. (ex. tuberculosis)
– Release toxins (poisons) that harm the body. (ex. Streptococcus and food poisoning)
• Many bacterial diseases can be prevented by stimulating the body’s immune system with vaccines.
• If a bacterial infection does occur, a number of drugs and natural compounds can be used to attack and destroy the invading bacteria. (antibiotics)
• See figure 19-10
• https://www.youtube.com/watch?v=ICWLF9lccNk (bacteria animation – 2 min)
Human Uses of Bacteria
• Bacteria are used in the production of a variety of foods (cheese, yogurt, buttermilk, sour cream, cheese, pickles, sauerkraut, and vinegar)
• Industry – oil spill clean up, mine minerals, synthesize drugs and chemicals)
Controlling Bacteria
• Most bacteria are harmless, and many are beneficial (ex. normal flora)
• However, to control bacteria:– Sterilization, heating, boiling, disinfectants, frying,
steaming– Refrigeration – slows food from spoiling– Canning – preserving food for a long time.– Inhibiting growth of bacteria – salt, vinegar, sugar.– https://www.youtube.com/watch?v=TVfmUfr8VPA
(ted talk on bacteria – 18 minutes)
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