MODULE #2: Kingdom Monera Prokaryota(pro kehreeaht' uh)

Transcription

1 MODULE #2: Kingdom Monera Prokaryota(pro kehreeaht' uh)

2 The general namebacteria(singular is bacterium) can essentially be applied to all of the organisms inkingdommonera. Pathogen An organism that causes disease

3 3 Basic Shapes of Bacteria These are false-color images.

4 Typical Bacterium All are prokaryotic; not all contain every organelle

5 Typical Bacterium capsule organic layer of sticky sugars

6 Typical Bacterium cell wall - 3 purposes:

7 cell wall - 1. holds the contents of the bacterium together, 2. regulates the amount of water that a bacterium can absorb, and 3. holds the cell into one of three basic shapes

8 Typical Bacterium plasma membrane -Made of phospholipids and proteins.

9 The plasma membrane regulates what the bacterium takes in from the outside world. 1. protects the interior of the cell by sensing the nature of the chemicals in the surroundings and then determining whether or not they can enter the cell.

10 The plasma membrane regulates what the bacterium takes in from the outside world. 2. In some cases, if the cell needs the chemicals, the plasma membrane will actuallyforcethe chemicals into the cell, whether they want to come in or not!

11 Typical Bacterium Cytoplasm exists throughout the interior of the cell, supporting the DNA and the ribosomes.

12 DNA holds all of the information required to make this mass of chemicals a living entity. Ribosomes are chemical factories that make proteins, Positioned throughout the cytoplasm are thousands of different types of chemicals which aid the parts of the cell in their tasks.

13 Typical Bacterium fimbriae-fibrous bristles used for grasping. If in reproduction, they re calledsex pili.

14 Typical Bacterium flagellum-used for motion. If a bacterium does not possess a flagellum, it cannot move.

15 The flagellum 3 Main Parts

16 The flagellum

17 The flagellum Basal Body

18 Question:Two different species of bacteria attempt to infect an organism. One bacterium succeeds, while the other is destroyed by the organism's infection-fighting mechanisms. What is most likely the major difference between these two bacteria?

19 Answer: The bacterium that succeeded most likely has a capsule while the other does not. In bacteria, the capsule helps to protect the organism from infection-fighting mechanisms.

20 Question:A bacterium is poisoned by a substance that is allowed into the interior of the cell. What bacterial component did not do its job?

21 Answer The plasma membranedid not do its job. Since it regulates what moves in and out of the cell, it should not have allowed the toxin to enter.

22 Question:If a bacterium cannot move, what structure is it missing?

23 Answer: It is missing a flagellum. The fimbriae are not for movement; thus, if a bacterium has no flagellum, it cannot move.

24 The Eating Habits of Bacteria Great diversity in the eating habits - there are producers, consumers, and decomposers in kingdom Monera. Most are heterotrophs rely on other organisms for food production. Most are decomposers referred to as saprophytes.

25 The Eating Habits of Bacteria Saprophyte An organism that feeds on dead matter

26 The Eating Habits of Bacteria Some bacteria are parasites. Parasite An organism that feeds on a living host Many parasitic bacteria lack the ability to digest nutrients, so they need to absorb nutrients that have already been digested. In addition, they often lack the ability to manufacture the complex chemicals necessary for life. As a result, they must also absorb those chemicals from their host.

27 Autotrophic Bacteria Two different means by which autotrophic bacteria manufacture their own food: 1.photosynthesis 2.chemosynthesis.

28 Photosynthesis in Bacteria Photosynthesis uses the energy from sunlight and certain chemicals to make food for the autotrophic organism. In green plants and most of the other photosynthetic organisms, the byproduct of photosynthesis is oxygen. In bacteria, photosynthesis does not have oxygen as a byproduct because the chemicals used are different from those used by plants. The byproducts of photosynthesis from bacteria are useful to certain organisms. (Module#5).

29 Chemosynthesis in Bacteria In chemosynthesis, the bacteria promote chemical reactions which release energy. The bacteria then use that energy, along with other chemicals, to manufacture their food. Usually, the chemical reactions that provide energy to chemosynthetic bacteria also convert chemicals that living organisms can't use into chemicals that certain living organisms can use. Thus, even though there are only a few types of chemosynthetic bacteria, they perform an essential function for many living organisms.

30 There must be a process by which food is converted into energy to support life. In humans, digestion does not give us energy. It simply breaks food down into smaller molecules. In order to get energy, we must then combine these molecules with oxygen (and burn our food). Since we use oxygen in order to get energy from our food, humans are called aerobic organisms. Aerobic organism An organism that requires oxygen

31 Some bacteria do not require oxygen in order to convert their food into energy. These bacteria are anaerobic organisms. Anaerobic organism An organism that does not require oxygen Typically, they live in areas that are barren of oxygen such as deep underground or in the muck at the bottom of a swamp. They either decompose dead organisms or convert useless chemicals into chemicals that can be used by other life forms.

32 Question:Can saprophytic bacteria be autotrophic?

33 Answer: No. Saprophytic means that it feeds on dead matter. Autotrophic organisms make their own food.

34 Question:Can an aerobic bacterium be chemosynthetic?

35 Answer: Yes. Aerobic and anaerobic deal with how the organism converts its food into useful energy. Chemosynthetic deals with how the organism gets the food to begin with. Thus, the bacterium can make the food chemosynthetically and then convert it to useable energy aerobically.

36 binary fission Asexual Reproduction in Bacteria

37 Asexual Reproduction in Bacteria

38 Asexual Reproduction in Bacteria

39 Asexual Reproduction in Bacteria

40 Asexual Reproduction in Bacteria

41 Asexual Reproduction in Bacteria

42 Speed of Reproduction & Its Repercussions Under ideal conditions, a bacterium can divide in about 20 minutes. Once it divides, the new bacteriumand the old onecan divide again in about 20 minutes. One bacterium could multiply into more than a billion bacteria in about 10 hours. In a week, the bacteria would have a combined weight that is larger than the entire planet!

43 Luckily, resources will run out eventually. Steady state A state in which members of a population die as quickly as new members are born

44 During the initial stage of population growth, the bacteria are reproducing unchecked. There are plenty of resources for the population, so the population grows as quickly as the bacteria can reproduce. This is called exponential growth. Exponential growth Population growth that is unhindered because of the abundance of resources for an ever-increasing population.

45 When you graph a population that experiences logistic growth, you get the S-shaped curve (often called a sigmoidal curve) that is shown in the pink section of the graph.

46 As the population begins to reach the limits of the environment's resources, it can no longer grow unchecked. The population growth is controlled by the limited resources of the environment. This is referred to as logistic growth. Logistic growth Population growth that is controlled by limited resources If you look at Figure 2.5 again, you will see that there is a region that is highlighted in pink. That is the region over which logistic growth occurs.

47 Question:A population of bacteria grown from a single starter bacterium is rather fragile. When conditions are changed, the population dies quickly. Based on what you have just learned, develop a hypothesis for why this is the case.

48 Answer: Since asexual reproduction allows no variation in the DNA, an entire population of bacteria started from a single bacterium have all the same traits. If the environment changes, an organism might need new traits to survive. Since the whole population has essentially the same traits, there is no way to get the needed new traits, and the population dies. The variability that exists in sexual reproduction usually makes a population much more resistant to changes in the habitat.

49 Question:A population of bacteria reaches a steady state and then, after several days, the population actually increases dramatically. What could cause such an event?

50 Answer: More resources (most likely food) were added to the habitat. The only way you can get population growthafterthe steady state would be due to an influx of new resources.

51 Genetic Recombination in Bacteria In asexual reproduction the offspring is a genetic copy of the parent. It is often beneficial for bacteria to exchange genetic information in order to increase the genetic diversity of the population. Bacteria do this bygenetic recombination, which can occur in one of three ways: 1. conjugation, 2. transformation, or 3.transduction.

52 Genetic Recombination in Bacteria Conjugation A temporary union of two organisms for the purpose of DNA transfer Conjugation is not sexual reproduction. No offspring is formed. Genetic information is transferred from a donor bacterium to a recipient.

53 Genetic Recombination in Bacteria Desirable traits present in some individuals are contained in a small, circular strand of DNA called aplasmid. The plasmid is an extra component, separate from the rest of the bacterium's DNA. Plasmid A small, circular section of extra DNA that confers one or more traits to a bacterium and can be reproduced separately from the main bacterial genetic code

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59 Question:A population of bacteria are living in a lake. Due to volcanic activity nearby, the lake's temperature begins to increase. In the population, there are some bacteria that are resistant to low temperatures (call them type A) and another type that are resistant to high temperature (call them type B). Which type will be the donor and which the recipient as the population begins to conjugate?

60 Answer: Type B will be the donors and Type A will be the recipients. Since the bacteria will need to survive in high temperatures, they need resistance to high temperatures. That's what will be donated.

61 Transformation Transformation The transfer of a DNA segment from a nonfunctional donor cell to that of a functional recipient cell 1. A bacterium dies 2. its cell wall falls apart and the components of the cell (including the DNA) flow into the surroundings. 3. the dead bacterium's DNA seems to break into small pieces, 4. a living bacterium might sense that one or more of those pieces contains a trait or traits that it could use. 5. The living bacterium then absorbs what it needs, incorporating the new genetic information as a plasmid.

62 Transduction Transduction The process in which infection by a virus results in DNA being transferred from one bacterium to another A virus can pick up DNA from a bacterium during infection and that DNA can be inserted into another bacterium in a subsequent infection.

63 Endospore Formation Imagine a sample of water that is filled with bacteria. You boil the water to try to kill the bacteria. Will that get rid of the population? Not necessarily. Although boiling water will kill the bacteria, they can actually survive the high temperature for some period of time by producing anendospore.

64 Endospore Formation Endospore The DNA and other essential parts of a bacterium coated with several hard layers

65 Endospore Formation The endospore is formedinsidethe bacterium's plasma membrane. Once an endospore forms, the bacterium itself might die, but as long as the endospore survives, the bacterium can reform.

66 Endospore Formation An endospore can withstand extreme situations (boiling/freezing/extreme dryness) for a lot longer than the bacterium itself. When favorable conditions return, the hard layers surrounding the DNA will deteriorate, and the cell will burst from the endospore, ready to grow and reproduce again.

67 Bacterial Colonies Many bacteria exist in colonies. The individual bacteria group together, but they all still exist as individuals. The bacteria's ability to survive is usually enhanced when they form a colony.

68 Bacterial Colonies As you might expect, bacteria form colonies in a variety of different ways. Bacteria take on one of three basic shapes: coccus(spherical), bacillus (rod-shaped), or spirillum(helical). The most common bacterial colonies are made up of either coccior bacilli bacteria.

69 The shape of the bacteria is often contained in the name so you automatically know something about the organism from just the name. If the bacteria are spherical, the name ends in coccus. If they are rod-shaped, the name ends in bacillus. You are expected to be able to determine the shape of a bacterium when it is a part of the name.

70 DNA seems to tell them what colony they should form. Exhibit group behavior: Some colonies, for example, will secrete a capsule-like substance that surrounds and protects the entire colony. Other colonies have bacteria that actually work together to capture and eat prey. AMyxococcusxanthuscolony, for example, moves as a unit in search of prey, typically other bacterial colonies. When they find their prey, they engulf it and, as a group, secrete a substance that digests it. The entire colony then feeds on the nutrients.

71 Question:A bacterial colony is called staphylobacillus. What shape do the bacteria in the colony possess: spherical, rod-shaped, or helical?

72 Answer: They are rod-shaped bacillus means rod-shaped.

73 Classification in Kingdom Monera Under a Gram stain, some bacteria turn red (Grampositive) and others turn blue (Gram-negative). Reaction caused by differences in the cell wall.

74 Classification in Kingdom Monera Phyla Gracilicutes(gruh' siluh kyoo' teez) bacteria has cell wall & Gram-negative m. Firmicutes(fir' muhkyoo' teez) bacteria has cell wall & Gram-positive. Tenericutes(ten' uh ruhkyoo' teez) bacteria does not have a cell wall. Mendosicutes(men' dohsuhkyoo' teez) bacteria has cell wall but the compounds are different from those that form Gram-positive or Gram-negative reactions..

75 Question:A bacterium has no cell wall. To what phylum does it belong?

76 Tenericutesis the phylum for bacteria without a cell wall.

77 Question: A bacterium is classified as Grampositive. To what phylum does it belong?

78 Answer: Firmicutes contains all Gram-positive bacteria.

79 Question:A bacterium appears red after a Gram stain. To what phylum does it belong?

80 Gracilicutescontains all Gram-negative bacteria. Since the bacterium appears red after the Gram stain, it is Gram-negative.

81 Question:A bacterium has a cell wall that is different from both Gram-positive and Gramnegative bacteria. To what phylum does it belong?

82 Answer: Mendosicutescontains all bacteria with exotic cell walls.

83 Class based on how bacteria obtains food.

84 Class based on shape.

85 Only 1 class.

86 Only 1 class. On Test You Will Be Expected To Be Able To Classify Based On Characteristics!

87 Question:Construct a biological key that separates bacteria into their different classes. You can assume that the only organisms the key will be used to analyze are bacteria. (HINT: The first question should determine whether or not the bacterium has a cell wall.)

88 Answer: See Table Cell wall...2 No cell wall...phylum Tenericutes...class Mollicutes 2. Gram-positive or Gram-negative...3 Neither...phylum Mendosicutes...class Archaebacteria 3. Gram-Positive...phylum Firmicutes...4 Gram-Negative...phylum Gracilicutes Bacillus or Coccus....class Firmibacteria Neither...class Thallobacteria 5.Non-photosynthetic...class Scotobacteria Photosynthetic Produces oxygen...class Oxyphotobacteria Does not produce oxygen...class Anoxyphotobacteria

89 A Few Words on Other Classification Systems Six-kingdomsystem. Retainskingdoms Protista, Fungi, Plantae, and Animalia, SplitskingdomMonerainto two separate kingdoms: ArchaebacteriaandEubacteria. Most of the organisms that we have placed in phylum Mendosicutes, class Archaebacteriaare put intokingdomarchaebacteria, Most of the rest are placed inkingdomeubacteria.

90 Specific Bacteria Class Archaebacteria Have cell walls Live in harsh conditions Anaerobic chemosynthetic bacteria belong to this class. Blue-Green Algae (al' jee) or Cyanobacteria (sye' an oh bak tehr'ee uh) Look like Algae Live in freshwater lakes and ponds and are most prevalent in stagnant waters. Form the blue-green mats that float on the surface of the water. Colonies of eukaryotic cells.- living in long, thin strands of cells that encapsulate themselves (feel slimy) Photosynthetc require light to survive

91 Specific Bacteria Clostridium (claw strid' ee um) botulinum (bot' yool in um) Class: Firmibacteria; Phylum: Firmicutes Source of food poisoning Heat resistant endospores produces a toxic chemical that causes botulism. Salmonella (sal muh nell' uh) typhimurium (tye' fim ur ee um) and S. enteriditis (en' ter uh dye' tus) Same genus: Salmonella; Phylum Gracilicutes; Class Scotobacteria. Common contaminants of eggs and poultry.

92 Specific Bacteria Escherichia(esh' uree' keeuh)coli(koh' lye) Phylum Gracilicutes; Class Scotobacteria. Very common, living in your gut. Its species name, coli refers to the colon, which is a part of your gut. Two Strains. Strains Organisms from the same species that have markedly different traits

93 Specific Bacteria Escherichia(esh' uree' keeuh)coli(koh' lye) 1) Nonpathogenic One of the byproducts ofe. coli's metabolism is Vitamin K Secretes a chemical that helps your body digest fat. Keeps food-borne pathogenic bacteria from colonizing in your gut. 2) Pathogenic causes severe diarrhea

94 Conditions For Bacterial Growth Moisture Moderate temperature: 27 C -38 C (80 F -100 F) Nutrition Darkness The proper amount of oxygen

95 Preventing Bacterial Infections Expose food to extreme heat or radiation Dehydrate food Prolonged freezing of food Pasteurization