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Chapter 17 Bacteria and Archaea Dentist: ©BSIP/Phototake; Biofilm: ©Dennis Kunkel Microscopy, Inc./Phototake Copyright © McGraw-Hill Education. All rights.

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Presentation on theme: "Chapter 17 Bacteria and Archaea Dentist: ©BSIP/Phototake; Biofilm: ©Dennis Kunkel Microscopy, Inc./Phototake Copyright © McGraw-Hill Education. All rights."— Presentation transcript:

1 Chapter 17 Bacteria and Archaea Dentist: ©BSIP/Phototake; Biofilm: ©Dennis Kunkel Microscopy, Inc./Phototake Copyright © McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.

2 What Are Prokaryotes? Section 17.1 A prokaryote is a single- celled organism that lacks a nucleus and membrane- bounded organelles. Figure 17.1 Bacteria: ©Kwangshin Kim/Science Source; Archaea: ©Ralph Robinson/Visuals Unlimited

3 What Are Prokaryotes? Bacteria and archaea are prokaryotes belonging to distinct domains. Section 17.1 Figure 17.1 Bacteria: ©Kwangshin Kim/Science Source; Archaea: ©Ralph Robinson/Visuals Unlimited

4 What Are Prokaryotes? DNA sequences and chemical composition distinguish these domains. Section 17.1 Figure 17.1 Bacteria: ©Kwangshin Kim/Science Source; Archaea: ©Ralph Robinson/Visuals Unlimited

5 What Are Prokaryotes? The first cells were likely prokaryotic. They have thrived for billions of years. Section 17.1 Figure 17.1 Bacteria: ©Kwangshin Kim/Science Source; Archaea: ©Ralph Robinson/Visuals Unlimited

6 Clicker Question #1 According to the evolutionary tree below, why might the term “prokaryote” be controversial among scientists? A. Prokaryotes are extinct. B. Prokaryotes consist of a small portion of life’s diversity. C. Prokaryotes consist of distantly related domains. D. All of the above are true. Flower: © Doug Sherman/Geofile/RF

7 Clicker Question #1 According to the evolutionary tree below, why might the term “prokaryote” be controversial among scientists? A. Prokaryotes are extinct. B. Prokaryotes consist of a small portion of life’s diversity. C. Prokaryotes consist of distantly related domains. D. All of the above are true. Flower: © Doug Sherman/Geofile/RF

8 17.1 Mastering Concepts What are two domains that contain prokaryotes? Dentist: ©BSIP/Phototake; Biofilm: ©Dennis Kunkel Microscopy, Inc./Phototake

9 Comparing Bacteria and Archaea Section 15.1 Figure 17.2 Section 17.2

10 The nucleoid is the region where the DNA resides. Comparing Bacteria and Archaea Figure 17.3 Section 17.2

11 Plasmids are circles of DNA apart from the chromosome. Comparing Bacteria and Archaea Figure 17.3 Section 17.2

12 Ribosomes use mRNA to synthesize proteins. Comparing Bacteria and Archaea Figure 17.3 Section 17.2

13 A pilus is a hair-like projection made of protein. Pili enable cells to adhere to objects. Comparing Bacteria and Archaea Figure 17.3 Section 17.2

14 A flagellum rotates like a propeller, allowing prokaryotes to move. Comparing Bacteria and Archaea Figure 17.3 Section 17.2

15 Flagella are used for taxis, movement toward or away from a stimulus. Comparing Bacteria and Archaea Figure 17.3 Section 17.2

16 The glycocalyx functions include protection and attachment. Comparing Bacteria and Archaea Figure 17.3 Section 17.2 The glycocalyx is a layer of proteins or polysaccharides surrounding the cell wall.

17 The cell wall gives the cell its shape. Comparing Bacteria and Archaea Figure 17.3 Section 17.2

18 Bacteria have two types of cell walls. Gram positive cells have a thick peptidoglycan (a carbohydrate) layer. Bacteria Cell Walls Are Multi-layered Figure 17.5 Section 17.2 Stained bacteria: ©Jack Bostrack/Visuals Unlimited Staining cells distinguishes bacteria based on cell wall type.

19 The three most common shapes are coccus (spherical), bacillus (rod-shaped), and spirillum (spiral). Coccus: © David M. Phillips/Visuals Unlimited; Bacillus: © SciMAT/Photo Researchers; Spirillum: © Ed Reschke/Peter Arnold/Photolibrary A Cell Wall Determines Cell Shape Figure 17.4 Section 17.2

20 Endospores Keep Some Bacteria Alive Section 15.1 Figure 17.7 Some bacteria form thick- walled endospores that survive harsh conditions. Clostridium botulinum, the cause of botulism, is one example. Section 17.2 Clostridium: ©Michael Abbey/Science Source

21 Scientists Classify Prokaryotes Based on Metabolic Pathways Section 15.1 Prokaryotes obtain carbon and energy in many ways. Section 17.2

22 Scientists Classify Prokaryotes Based on Metabolic Pathways Section 15.1 Oxygen requirements are also important in classification. Aerobic habitats house obligate aerobes and facultative anaerobes; anaerobic habitats are home to obligate and facultative anaerobes. Section 17.2 Figure 17.8

23 DNA sequences, such as those that encode ribosomal RNA, are important for distinguishing archaea and bacteria. Section 17.2 Figure 17.1 Scientists Classify Prokaryotes Based on Molecular Data Bacteria: ©Kwangshin Kim/Science Source; Archaea: ©Ralph Robinson/Visuals Unlimited

24 Clicker Question #2 Bacteria, archaea, and eukaryotes all have ribosomes, but ribosome structure slightly varies between these groups. What is the best explanation for this observation? A. The common ancestor of these three domains had ribosomes; slight changes have accumulated since the lineages split. B. Ribosomes arose independently in all three groups. Flower: © Doug Sherman/Geofile/RF

25 Clicker Question #2 Bacteria, archaea, and eukaryotes all have ribosomes, but ribosome structure slightly varies between these groups. What is the best explanation for this observation? A. The common ancestor of these three domains had ribosomes; slight changes have accumulated since the lineages split. B. Ribosomes arose independently in all three groups. Flower: © Doug Sherman/Geofile/RF

26 Section 17.2 Figure 17.9 Prokaryotes Transmit DNA Vertically and Horizontally Vertical gene transferHorizontal gene transfer

27 Section 17.2 Prokaryotes Transmit DNA Vertically and Horizontally Vertical gene transfer Vertical gene transfer is also called binary fission. It is an asexual process that replicates DNA and distributes it to two cells.

28 Section 17.2 Figure 17.9 Prokaryotes Transmit DNA Vertically and Horizontally Horizontal gene transfer In horizontal gene transfer, a cell receives DNA from a cell that is not its ancestor. This occurs in three ways.

29 Section 17.2 Figure 17.9 Prokaryotes Transmit DNA Vertically and Horizontally Horizontal gene transfer: Transformation

30 Section 17.2 Figure 17.9 Prokaryotes Transmit DNA Vertically and Horizontally Horizontal gene transfer: Transduction

31 Section 17.2 Figure 17.9 Prokaryotes Transmit DNA Vertically and Horizontally Horizontal gene transfer: Conjugation

32 Clicker Question #3 What type of horizontal gene transfer relies on direct contact between two bacteria? A. Transduction B. Transformation C. Conjugation D. Binary fission Flower: © Doug Sherman/Geofile/RF

33 Clicker Question #3 What type of horizontal gene transfer relies on direct contact between two bacteria? A. Transduction B. Transformation C. Conjugation D. Binary fission Flower: © Doug Sherman/Geofile/RF

34 17.2 Mastering Concepts Distinguish between vertical and horizontal gene transfer. Dentist: ©BSIP/Phototake; Biofilm: ©Dennis Kunkel Microscopy, Inc./Phototake

35 The Diversity of Domain Bacteria Section 15.1 Figure Proteobacteria (left image) form one phylum of bacteria; their metabolic pathways and habitats are diverse. Section 17.3 Proteobacteria Bacteria: ©Dr Gopal Murti/Science Source; Anabaena: ©John Walsh/Science Source

36 The Diversity of Domain Bacteria E. coli and Salmonella are types of proteobacteria. Proteobacteria Figure Section 17.3 Bacteria: ©Dr Gopal Murti/Science Source; Anabaena: ©John Walsh/Science Source

37 The Diversity of Domain Bacteria Cyanobacteria (right image) form another phylum of bacteria. These autotrophs were the first to release oxygen gas as a byproduct of photosynthesis. ProteobacteriaCyanobacteria Figure Section 17.3 Bacteria: ©Dr Gopal Murti/Science Source; Anabaena: ©John Walsh/Science Source

38 The Diversity of Domain Bacteria Other phyla of bacteria include Spirochaetes, Firmicutes, actinobacteria, and Chlamydiae. ProteobacteriaCyanobacteria Figure Section 17.3 Bacteria: ©Dr Gopal Murti/Science Source; Anabaena: ©John Walsh/Science Source

39 The Diversity of Domain Archaea Domain Archaea are often collectively called extremophiles, since this domain was first discovered in extreme habitats. Figure Section 17.3 Archaea habitat: ©Ralph Eagle Jr./Science Source; Inset: ©Eye of Science/Science Source Archaea often live in places that lack oxygen or that are extremely hot, salty, or acidic. But some live in moderate environments.

40 The Diversity of Domain Archaea Archaea are essential in geochemical cycles on land and in water. Figure Section 17.3 Archaea habitat: ©Ralph Eagle Jr./Science Source; Inset: ©Eye of Science/Science Source Scientists are only beginning to organize Domain Archaea into phyla. Euryarchaeota Crenarchaeota Korarchaeota

41 Clicker Question #4 Where (approximately) would you expect to find Salmonella on the evolutionary tree below? A B C D Flower: © Doug Sherman/Geofile/RF

42 Clicker Question #4 Where (approximately) would you expect to find Salmonella on the evolutionary tree below? A B C D Flower: © Doug Sherman/Geofile/RF

43 Prokaryotes Are Essential to Life Prokaryotes in root nodules of some plants carry out nitrogen fixation, an essential process in which atmospheric nitrogen (N 2 ) is converted to ammonia. Figure Section 17.4 Rhizobium: ©Dr. John D. Cunningham/Visuals Unlimited; Root nodule cross section: ©Science VU/Visuals Unlimited Only a few species of bacteria and archaea can use N 2. Without nitrogen fixation, most nitrogen would be locked in the atmosphere.

44 Prokaryotes Are Essential to Life Harmless bacteria in our bodies help crowd out pathogenic bacteria. Figure Section 17.4

45 Prokaryotes Are Essential to Life Section 17.4 Harmful bacteria might be ingested or inhaled, or they enter the body through wounds or orifices. Salmonella is in undercooked eggs. Raw egg: ©Ingram Publishing RF

46 Prokaryotes Are Essential to Life Section 15.1 When we take antibiotics, some of our resident microbes die, sometimes leading to secondary infections. Section 17.4 Pill: ©Rick Gomez/Corbis RF

47 Prokaryotes Are Essential to Life Section 15.1 Prokaryotes also help make food and drugs. In wastewater treatment plants, microbes help break down organic matter. Section 17.4 Figure Making cheese: ©Joe Munroe/Science Source; Humulin: ©David Wrobel/Visuals Unlimited ; Filter process: ©Jonathan A. Meyers/Science Source

48 Prokaryotes Are Everywhere Section 15.1Section 17.4 Figure This image shows a tiny sampling of the diversity of prokaryotes (bacteria, in this case) found at a park.

49 Clicker Question #5 Are the prokaryotes that typically reside inside of us useful? A. No, we would be in better health without these microbes. B. Yes, they help crowd out harmful prokaryotes. Flower: © Doug Sherman/Geofile/RF

50 Clicker Question #5 Are the prokaryotes that typically reside inside of us useful? A. No, we would be in better health without these microbes. B. Yes, they help crowd out harmful prokaryotes Flower: © Doug Sherman/Geofile/RF

51 17.5 Mastering Concepts In what ways are bacteria and archaea important to eukaryotic life in general and to human life in particular? Dentist: ©BSIP/Phototake; Biofilm: ©Dennis Kunkel Microscopy, Inc./Phototake

52 Section 17.5 Figure Investigating Life: A Bacterial Genome Solves Two Mysteries Scientists used bacterial DNA to determine the origins of antibiotic resistant bacteria (MRSA). Their results indicate that antibiotic resistance has evolved independently several times.

53 Section 17.5 Figure Investigating Life: A Bacterial Genome Solves Two Mysteries They also determined that bacteria that cause toxic shock syndrome have several separate origins.

54 Section 17.5 Figure Investigating Life: A Bacterial Genome Solves Two Mysteries Researching bacteria evolution helps to prevent the spread of disease.


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