Kingdom Bacteria Kingdom Archaea

Transcription

1 Section 5.1 Kingdom Bacteria Kingdom Archaea p Kingdom Bacteria General Characteristics: Cell Type: all are prokaryotic. Body Form: most are unicellular, some are colonial. Three main shapes are: cocci which are round bacilli which are rod shaped spirilli which are spiral shaped Also grow in patterns: diplo are in pairs staphylo are in clusters strepto are in chains 1

2 Cell Wall: most bacteria have one, often contains peptidoglycan. The cell wall structure and thickness is determined by using a Gram Stain which was developed by Hans Gram. Gram-positive bacteria have thick walls and peptidoglycan, which is carbohydrates and proteins. These stain purple. Gram-negative bacteria have two cell walls. These stain pink. This type is more common. Locomotion: Many are motile, some are nonmotile. The ones that are motile move by means of cilia or flagella. Nutrition: They can be autotrophs (photosynthetic or chemosynthetic) and they can be heterotrophs. There are four groupings based on nutrition: photoautotrophs photoheterotrophs chemoautotrophs chemoheterotrophs Refer to page 133 2

3 Reproduction: Asexual Reproduction by Binary Fission: One parent Genetic material replicates. Cell elongates. Septum forms to make two distinct cells. Daughter cells are formed; they are exact copies of parent cell. This can occur every 20 minutes. Sexual Reproduction by Conjugation: Two parents (or more in the case of bacteria) cells become linked and exchange chromosomes. Other possible types of bacteria reproduction: Gene transfer through plasmids. This is used in genetic engineering. Spore formation. Involves the production of endospores which are composed of DNA and a small amount of cytoplasm. They can resist extreme heat or cold, dryness and chemicals. Bacteria play vital roles in ecosystems. They are needed for the survival of ecosystems because are important in the nutrient cycles; such as the carbon and nitrogen cycles. They are classified by their shape, the structure of their cell walls, and their sources of food and energy. Bacteria are found in the air, in the soil, in the water, and on and inside you. They make up the greatest number of organisms. They can cause infection inside humans if they build up to a large number. Antibiotics are used to stop the growth of bacteria. Sometimes, bacteria can create a resistance to the antibiotics and then their usefulness declines. 3

4 Examples: Bacteria Cyanobacteria Blue-green algae E. Coli Kingdom Archaea General Characteristics: Cell Type: all are prokaryotic. Body Form: most are unicellular, some are colonial. There is considerable variation in size; from the microscopic unicellular arrangements to the very long (over 200m long filaments). They can be cocci (round), bacilli (rod-shaped), and spirilli (spiral) shapes (some are triangular and square shape). 4

5 Cell Wall: Archaea have a different cell wall structure than bacteria - No peptidoglycan. Archaea have unusual lipids (fats) that remain stable at very high temperatures or very low temperatures. Locomotion: Some archaea, like bacteria, do not have movement. Others that can move, do so through 1 or more flagella (same as bacteria). So, many are motile, some are non-motile. Nutrition: Archaea are chemosynthetic (chemotrophic) bacteria species which can make their own food by converting inorganic substances such as methane and sulphur into organic food. They can be autotrophs: Photosynthetic Chemosynthetic They can be heterotrophs Reproduction: Asexual (binary fission) most common Sexual (conjugation) See bacteria notes on this 5

6 Many members of this kingdom are extremeophiles that is they live in extreme environments, including water whose temperature exceeds that of boiling water (such as hot spring geysers and sub sea (sea floor) vents). They are also found in acidic or alkaline environments, saline (salty) environments, inside volcanoes, as well as deep below the earth surface. They are very diverse, both in form and function. These organisms are used in biotechnology Archaea differ from the Bacteria in many important respects, as well as from the eukaryotes. These differences include: The wall structure and chemistry The lipids that make up their membrane Their metabolism They look like members of kingdom Bacteria but their genetic material is very different. 6

7 There is also something special about members of this kingdom because some are able to do cellular respiration without the presence of a certain chemical: Oxygen. So, Archaea can be Aerobic or Anaerobic. Aerobic: use oxygen to carry out life s processes. Anaerobic: do not need oxygen to carry out life s processes. Instead they use: Methane ( CH 4 ) Carbon Dioxide (CO 2 ) Nitrogen Gas (N 2 ) Hydrogen Sulfide (H 2 S) Examples: Some are methanogens - organisms which can use methane for food. These live in the guts of animals, such as cows. Others are thermophiles - organisms which live under extreme temperatures in hot springs. They often can convert the sulphur in hot water springs into food. Halophiles live in salt lakes. 7

8 Life Cycle of E. Coli A bacteria representing the Kingdoms Bacteria & Archaea. Reproduce asexually using method called binary fission. Can also reproduce sexually using a method called conjugation. Binary Fission (Asexual) (see diagram in text p. 134, fig. 5.4) Each bacteria has a single chromosome. Before fission, the bacteria makes a copy of this chromosome, so it has 2 chromosomes. Binary fission has 4 stages: A. Elongation - when ready to divide, the bacteria gets longer. B. A septum begins to form - an extension of the cell wall. Chromosomes separate to opposite sides of the cell. C. The septum fully forms, separating the bacteria into 2 cells. D. the bacterium splits into 2 genetically identical bacteria. Binary fission takes about 20 min in good conditions. This leads to exponential growth of their populations. Binary fission rate is limited by: (1) predation (2) unfavorable conditions ( 3) food Has a huge reproductive capacity ( 1 bacterium dividing can result in 1,000,000 offspring being produced in hours) Waste products from some types of disease - causing bacteria produce toxins that lead to food poisoning or infections in humans. Many bacteria are beneficial to us. We use bacteria to treat sewage, decompose compost, make cheese and yogurt. Their ability to rapidly multiply is useful for such processes. 8

9 Conjugation (Sexual) (see diagram on p. 135, fig. 5.5) Happens during less favorable conditions Produces genetic variation in offspring - mixes up the genes for better chances of survival. Conjugation has 4 stages: A. A pilus forms (Pilus - bridging structures made up of hair-like tubes that allow microscopic organisms to exchange genetic material during a form of sexual reproduction, such as conjugation) B. Two bacteria become connected via the pilus C. one bacteria transfers all or part of its chromosome to the other bacteria D. the recipient bacteria uses the received chromosome material and later starts to divide by using asexual binary fission. In this way, all of the offspring are now genetically different than either parent. 9