End Show Slide 1 of 40 Biology Mr. Karns Bacteria

End Show Slide 2 of 40 19–1 Bacteria

End Show 19–1 Bacteria Slide 3 of Bacteria The smallest and most common microorganisms are prokaryotes—unicellular organisms that lack a nucleus.

End Show 19–1 Bacteria Slide 4 of 40 Classifying Prokaryotes All prokaryotes were once placed in the Kingdom Monera. Recently, biologists divided them into two different kingdoms: the Eubacteria and the Archaebacteria. Add Eu and Archae to your derivational terms

End Show 19–1 Bacteria Slide 5 of 40 Classifying Prokaryotes How do the two groups of prokaryotes differ?

End Show 19–1 Bacteria Slide 6 of 40 Classifying Prokaryotes Eubacteria Eubacteria have a cell wall that protects the cell and determines its shape. The cell wall of eubacteria contain peptidoglycan. Eubacteria have a cell membrane that surrounds the cytoplasm. Some eubacteria have a second membrane that provides added protection.

End Show 19–1 Bacteria Slide 7 of 40 Classifying Prokaryotes E. coli, a Typical Eubacterium Peptidoglycan Cell Membrane Ribosomes Pili DNA Flagellum Cell Wall

End Show 19–1 Bacteria Slide 8 of 40 Classifying Prokaryotes Eubacteria include organisms that live in a variety of environments, including: in fresh and salt water on land in the human body

End Show 19–1 Bacteria Slide 9 of 40 Classifying Prokaryotes Archaebacteria The cells walls of archaebacteria do not contain peptidoglycan. Archaebacteria have different membrane lipids. In addition, the DNA sequences of key archaebacterial genes are more like those of eukaryotes than those of eubacteria.

End Show 19–1 Bacteria Slide 10 of 40 Classifying Prokaryotes Many archaebacteria live in extreme environments. Methanogens live in oxygen-free environments, such as thick mud and animal digestive tracts. Other archaebacteria live in salty environments or in hot springs where water temperatures approach the boiling point. Halogenic

End Show 19–1 Bacteria Slide 11 of 40 Identifying Prokaryotes What factors are used to identify prokaryotes?

End Show 19–1 Bacteria Slide 12 of 40 Identifying Prokaryotes Prokaryotes are identified by characteristics such as: shape the chemical nature of their cell walls the way they move the way they obtain energy

End Show 19–1 Bacteria Slide 13 of 40 Identifying Prokaryotes Shapes Rod-shaped prokaryotes are called bacilli. Bacilli

End Show 19–1 Bacteria Slide 14 of 40 Identifying Prokaryotes Spherical prokaryotes are called cocci. Cocci

End Show 19–1 Bacteria Slide 15 of 40 Identifying Prokaryotes Spiral and corkscrew-shaped prokaryotes are called spirilla. Spirilla

End Show 19–1 Bacteria Slide 16 of 40 Identifying Prokaryotes A fourth shape of prokaryotes are called vibrios. These are short curved rods. Without proper magnification and resolution these are often termed bacillus or spirillum, but are actually properly called vibrios.

End Show 19–1 Bacteria Slide 17 of 40 Identifying Prokaryotes Cell Walls Two different types of cell walls are found in eubacteria. A method called gram staining tells them apart. Gram-positive bacteria have thick cell walls with large amounts of peptidoglycan. Gram-negative bacteria have thinner cell walls inside an outer lipid layer.

End Show 19–1 Bacteria Slide 18 of 40 Identifying Prokaryotes Gram-positive vs. Gram negative: why do you care? Antibiotics work by breaking down the cell wall of gram positive bacteria. Gram negative one are not as affected as their cell wall, so it is important to know what type of bacterial infection one has. Other drugs may be prescribed for certain gram negative strains- sulfa drugs for example.

End Show 19–1 Bacteria Slide 19 of 40 Identifying Prokaryotes Movement Prokaryotes can be identified by whether they move and how they move.

End Show 19–1 Bacteria Slide 20 of 40 Metabolic Diversity Prokaryotes are divided into two main groups: Heterotrophs get their energy by consuming organic molecules made by other organisms. Autotrophs make their own food from inorganic molecules.

End Show 19–1 Bacteria Slide 21 of 40 Metabolic Diversity Heterotrophs Prokaryotes that take in organic molecules for both energy and a supply of carbon are called chemoheterotrophs. Prokaryotes that use sunlight for energy, but take in organic compounds as a carbon source are called photoheterotrophs.

End Show 19–1 Bacteria Slide 22 of 40 Metabolic Diversity Autotrophs Photoautotrophs use light energy to convert carbon dioxide and water to carbon compounds and oxygen. Chemoautotrophs perform chemosynthesis. They make organic carbon molecules from carbon dioxide, but do not require light as energy.

End Show 19–1 Bacteria Slide 23 of 40 Metabolic Diversity Releasing Energy Bacteria need a constant supply of energy, which is released by the processes of cellular respiration or fermentation or both.

End Show 19–1 Bacteria Slide 24 of 40 Metabolic Diversity Obligate aerobes require a constant supply of oxygen. Bacteria that live without oxygen because they may be killed by it are called obligate anaerobes. Bacteria that can survive with or without oxygen are known as facultative anaerobes.

End Show 19–1 Bacteria Slide 25 of 40 Growth and Reproduction Most prokaryotes reproduce by binary fission. Some prokaryotes take part in conjugation. Other prokaryotes produce spores.

End Show 19–1 Bacteria Slide 26 of 40 Growth and Reproduction Binary Fission Binary fission is a type of asexual reproduction in which an organism replicates its DNA and divides in half, producing two identical daughter cells.

End Show 19–1 Bacteria Slide 27 of 40 Growth and Reproduction Binary Fission

End Show 19–1 Bacteria Slide 28 of 40 Growth and Reproduction Conjugation During conjugation, a hollow bridge forms between two bacterial cells, and genes move from one cell to the other. This transfer of genetic information increases genetic diversity in populations of bacteria.

End Show 19–1 Bacteria Slide 29 of 40 Growth and Reproduction Conjugation

End Show 19–1 Bacteria Slide 30 of 40 Growth and Reproduction Spore Formation In unfavorable growth conditions, many bacteria form spores. An endospore forms when a bacterium produces a thick internal wall that encloses its DNA and some of its cytoplasm. Spores can remain dormant for months or years. Spores allow bacteria to survive harsh conditions.

End Show 19–1 Bacteria Slide 31 of 40 Growth and Reproduction Spore Formation

End Show 19–1 Bacteria Slide 32 of 40 Importance of Bacteria What is the importance of bacteria?

End Show 19–1 Bacteria Slide 33 of 40 Importance of Bacteria Bacteria are vital to the living world. Some are producers that capture energy by photosynthesis. Others are decomposers that break down the nutrients in dead matter. Still other bacteria have human uses.

End Show 19–1 Bacteria Slide 34 of 40 Importance of Bacteria Decomposers Bacteria recycle nutrients and maintain equilibrium in the environment. Bacteria also help in the treatment of sewage.

End Show 19–1 Bacteria Slide 35 of 40 Importance of Bacteria Nitrogen Fixers Plants need nitrogen gas to be changed chemically to ammonia or other nitrogen compounds, which certain bacteria produce. The process of converting nitrogen gas into a form plants can use is known as nitrogen fixation. Many plants have symbiotic relationships with nitrogen-fixing bacteria.

End Show 19–1 Bacteria Slide 36 of 40 Importance of Bacteria Human Uses of Bacteria We depend on bacteria for many things, including: foods and beverages removal of waste and poisons from water mining minerals from the ground synthesis of drugs and chemicals via genetic engineering production of vitamins in human intestines

End Show - or - Continue to: Click to Launch: Slide 37 of 40 19–1

End Show Slide 38 of 40 19–1 Which characteristic distinguishes eubacteria from archaebacteria? a.Eubacteria lack peptidoglycan in their cell walls. b.Eubacteria contain peptidoglycan in their cell walls. c.Eubacteria lack a nucleus. d.Eubacteria do not possess mitochondria.

End Show Slide 39 of 40 19–1 Rod-shaped prokaryotes are called a.bacilli. b.cocci. c.spirilla. d.streptococci.

End Show Slide 40 of 40 19–1 Bacteria that must live without oxygen are called a.obligate aerobes. b.facultative anaerobes. c.obligate anaerobes. d.facultative aerobes.

End Show Slide 41 of 40 19–1 Prokaryotes that make their own food molecules from carbon dioxide and water but live where there is no light are called a.photoautotrophs. b.photoheterotrophs. c.chemoautotrophs. d.chemoheterotrophs.

End Show Slide 42 of 40 19–1 Bacteria that attack and digest the tissue of dead organisms are called a.decomposers. b.nitrogen fixers. c.chemoautotrophs. d.archaebacteria.

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