L7.1 What are Bacteria? PDF

Lesson 7.1 What are bacteria? pages 230-236 1  Lesson Objectives By the end of this lesson, you will be able to:  Classify bacteria  Identify the main parts of a bacteria cell and describe the function of each part  Identify the ways of re...

Lesson 7.1 What are bacteria? pages 230-236 1  Lesson Objectives By the end of this lesson, you will be able to:  Classify bacteria  Identify the main parts of a bacteria cell and describe the function of each part  Identify the ways of reproduction in bacteria 2  What are bacteria Bacteria (singular bacterium) are unicellular microscopic prokaryotes. A prokaryote is a unicellular organism that does not have a nucleus or other membrane-bound organelles. 3  Introduction to Bacteria 2 TYPES OF BACTERIA: Bacteria -Get food from an outside source Blue-green Bacteria -Make their own food 4  BACTERIA Bacteria - small one celled monerans Bacteria like a warm, dark , and moist environment They are found almost everywhere on earth : -water -air -soil -food -skin -inside the body -on most objects 5  3 Shapes of Bacteria Bacteria are classified by shape into 3 groups: Spiral: spirilla rod-shaped: bacilli, bacillus Round: cocci 6 3 Shapes of Bacteria Bacillus anthracis – (bacillus) Neisseria meningitidis (coccus) Leptospira interrogans – (spirilla) 7  7 Major Structures of a Bacteria Cell Capsule Cell wall Ribosomes Nucleoid Flagella Pilli Cytoplasm 8  7 Major Structures of a Bacteria Cell Capsule  keeps the cell from drying out and helps it stick to food or other cells 9  7 Major Structures of a Bacteria Cell Cell wall Thick outer covering that maintains the overall shape of the bacterial cell 10  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 11  7 Major Structures of a Bacteria Cell Nucleoid  a ring made up of DNA 12  7 Major Structures of a Bacteria Cell Flagella  a whip-like tail that some bacteria have for locomotion 13  7 Major Structures of a Bacteria Cell Pili  hollow hair-like structures made of protein allows bacteria to attach to other cells. Pili-plural Pilus-singular 14  7 Major Structures of a Bacteria Cell Cytoplasm  clear jelly-like material that makes up most of the cell 15 Video: parts of a bacterial cell 16  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 17  Reproduction of Bacteria BINAR Y FISSION Bacteria dividing Completed 18  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 (one bacterium could be an ancestor to one million bacteria in six hours) 19 Bacterial Cell & Nucleiod DNA Ring DNA replication Cell wall synthesis Cell separation 20 Bacterial conjugation and recombination Bacteria produced by fission are identical to the parent cell. However, genetic variation can be increased by a process called conjugation. During conjugation, two bacteria of the same species attach to each other and combine their genetic material. DNA is transferred between the bacteria. This results in new combination of genes, increasing genetic diversity. NB: New organisms are not produced during conjugation. So the process is not considered reproduction 21 22  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, The ability to form endospores enables bacteria to survive freezing, and extremely dry extreme conditions that would conditions normally kill them. It enables the bacteria to remain dormant for it encloses all the nuclear months or even centuries materials and some cytoplasm 23 24  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. 25  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 26  Harmful Bacteria some bacteria cause diseases 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 27  Harmful Bacteria Human tooth with accumulation of bacterial plaque (smooth areas) and calcified tartar (rough areas) 28  Helpful Bacteria Decomposers help recycle nutrients into the soil for other organisms to grow Bacteria grow in the stomach of a cow to break down grass and hay Most are used to make antibiotics Some bacteria help make insulin Used to make industrial chemicals 29  Helpful Bacteria E.coli on small intestines 30  Helpful Bacteria Used to treat sewage Organic waste is consumed by the bacteria, used as nutrients by the bacteria, and is no longer present to produce odors, sludge, pollution, or unsightly mess. foods like yogurt, cottage & Swiss cheese, sour cream, buttermilk are made from bacteria that grows in milk 31 Which is not a common bacteria shape? A) Rod B) Sphere C) Spiral D) square correct 32 Which process increases genetic diversity in bacteria? A) Attachment to a host organism B) Division into two organisms C) Formation of an endospore D) Transfer of plasmid strand correct 33 Which is not a characteristic of bacteria? A) They are microscopic B) They are unicellular C) They can live in many environments D) They have a membrane-bound organelle correct 34 This diagram illustrates a bacterium. What is the function of the structure labelled A? A) Attach to surfaces correct B) Sensing surroundings C) Stinging prey D) Taking in nutrients 35 36