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There are more bacteria on Earth than all other living things combined! • Sizes vary, but most cannot be see w/o a microscope Characteristics of Bacteria • • • • Two kingdoms All single-celled (unicellular) Prokaryotes (no nucleus) Rigid cell wall Charac. Contd. • Three main shapes: – Bacilli-rod shaped – Cocci-spherical – Spirilla-long and spiral shaped 3 Shapes of Bacteria Bacteria are classified by shape into 3 groups: Spiral: Spirilla, spirillum rod-shaped: bacilli, bacillus Round:cocci 4 3 Shapes of Bacteria Bacillus anthracis – (bacillus) Neisseria meningitidis (coccus) Leptospira interrogans – (spirilla) 5 7 Major Structures of a Bacteria Cell •Capsule •Cell wall •Ribosomes •Nucleoid •Flagella •Pilli •Cytoplasm 6 7 Major Structures of a Bacteria Cell Capsule keeps the cell from drying out and helps it stick to food or other cells 7 7 Major Structures of a Bacteria Cell Cell wall Thick outer covering that maintains the overall shape of the bacterial cell 8 7 Major Structures of a Bacteria Cell Ribosomes cell part where proteins are made Ribosomes give the cytoplasm of bacteria a granular appearance in electron micrographs 9 7 Major Structures of a Bacteria Cell Nucleoid a ring made up of DNA-the genetic material (chromosome) 10 7 Major Structures of a Bacteria Cell Flagella a whip-like tail that some bacteria have for locomotion 11 7 Major Structures of a Bacteria Cell Pilli hollow hair-like structures made of protein allows bacteria to attach to other cells. Pilli-singular Pillus-plural 12 7 Major Structures of a Bacteria Cell Cytoplasm clear jelly-like material that makes up most of the cell 13 • Some bacteria contain a plasmid- An extra, circular piece of DNA • Independent of the nucleoid and can replicate separately and may be transferred between bacteria Reproduction of Bacteria •Binary Fission- the process of one organism dividing into two organisms •Fission is a type of asexual reproduction •Asexual reproduction- reproduction of a living thing from only one parent How?... The one main (circular) chromosome makes a copy of itself Then it divides into two 15 Bacterial reproduction • Binary fissionasexual reproduction where one cell splits into two identical cells Reproduction of Bacteria BINARY FISSION Bacteria dividing Completed 17 Reproduction of Bacteria •The time of reproduction depends on how desirable the conditions are •Bacteria can rapidly reproduce themselves in warm, dark, and moist conditions •Some can reproduce every 20 minutes 18 Conjugation • Reproduction in bacteria that results in the exchange of genetic information Bacteria Survival Endospore•a thick celled structure that forms inside the cell •they are the major cause of food poisoning •allows the bacteria to survive for many years •they can withstand boiling, freezing, and extremely dry conditions •it encloses all the nuclear materials and some cytoplasm 20 Bacteria Survival Bacillus subtilis Endospore-the black section in the middle highly resistant structures can withstand radiation, UV light, and boiling at 120oC for 15 minutes. 21 Bacteria Survival – Food sources parasites – bacteria that feed on living things saprophytes – use dead materials for food (exclusively) decomposers – get food from breaking down dead matter into simple chemicals important- because they send minerals and other materials back into the soil so other organisms can use them 23 Kingdom Eubacteria • Has more individuals than all of the other 5 kingdoms combined • Classified by how get food: – Consumers (eat other organisms) – Decomposers (break down dead organisms) – Producers (make food) Kingdom Archaebacteria • Prefer harsh environ. with little or no oxygen • 3 main types: – Thermophiles or Thermoacidophiles-Heat lovers (hot springs, volcanic vents) – Halophiles- Salt lovers (highly salty water) – Methanogens- Methane makers (swamps & animal intestines) Bacteria are good for the environment! • Nitrogen fixation -change nitrogen from air into form plants can use • Recycling- Break down dead plants & animals • Bioremediation- Fight pollution, change harmful chemicals into harmless ones Also good for people! • In food- Make cheese, yogurt, etc. • Medicines- antibiotics • Insulin- bacteria can make human insulin, given to diabetics • Genetic engineering- can make insecticides, cleaners, & adhesives Helpful Bacteria E.coli on small intestines 29 Some bacteria are harmful! • Pathogenic bacteria- cause disease • Not only in humans; but in other animals, plants, protists, fungi, & other bacteria! • Ex. In humans: tetanus & diptheria Harmful Bacteria •Animals can pass diseases to humans Communicable Disease – Disease passed from one organism to another This can happen in several ways: •Air •Touching clothing, food, silverware, or toothbrush •Drinking water that contains bacteria 31 What is a virus? • Microscopic particle that gets inside a cell & often destroys • Strand of genetic material surrounded by a protein coat • Many cause diseases: – Common cold – Flu – Chickenpox – AIDS Little Bitty • Viruses are smaller than the smallest bacteria • 5 billion virus particles can fit into a single drop of blood Not living! • Cannot grow, eat, break down food, or use oxygen • Uses a host cell’s machinery • Host-living thing a parasite or virus lives on Lytic Cycle Lytic & Lysogenic Cycles