Test 2 Lecture Notes

Test 2 Lecture Notes - Test 2 Lecture Notes Chapter 27...

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Test 2 Lecture Notes Chapter 27: Prokaryotes Concept 27.1: Structural and functional adaptations contribute to prokaryotic success Prokaryotes are unicellular Some colonial forms Range from 1-5 micrometers No membrane bound organelles Circular Chromosomes Prokaryotic Cells have a variety of Shapes Spheres = cocci Rods = bacilli Spirals = spirilli Figure 27.2 Cell-surface Structures Cell Wall Maintains cell shape; provides physical protection; prevents cell from bursting in a hypotonic environment
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Composed of peptidoglycans in bacteria May also have outer phospholipid membrane Figure 27.3 Gram Positive = purple Gram Negative = Red Cell Surface Structures A capsule (Sticky layer of polysaccharide or protein) Fimbrae and pilli allow prokaryotes to stick to their substrate or other individuals in a colony Figures 27.4 and 27.5 Clicker Question Gram negative bacteria have ______ peptidoglycan than gram positive cells and their walls are ______ complex structurally. Less, More Motility Motile bacteria move using a flagellae ( Figure 27.6) Structurally different from eukaryotic flagella
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In a heterogeneous environment, bacteria exhibit taxis (ability to move toward or away from certain stimuli) E.g.: Positive chemotaxis moving toward a chemical stimulus Internal Organization Prokaryotes have no membrane bound organelles Some do have specialized membrane structures that perform metabolic functions ( Figure 27.7) Genomic Organization Prokaryotic Chromosome (circular chromosome found in the nucleoid region) Not within the nucleus Plasmid (smaller, circular DNA rings) Additional genes not always necessary for basic survival E.g.: Antibiotic Resistance Reproduction Prokaryotes reproduce quickly by using binary fission Can divide every 1-3 Hours
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Form of asexual reproduction Produces genetically identical Daughter cells Concept 27.2: Rapid reproduction, mutation, and genetic recombination promote genetic diversity in prokaryotes Bacteria reproduce asexually leading to genetically identical daughter cells Rapid Reproduction yields high populations and high mutation rates High Genetic Diversity and rapid evolutionary rates Genetic Exchange Bacterial Conjugation Transfer of genetic material between two bacteria Not necessarily the same species (Horizontal Gene Transfer) Plasmids usually transmitted from donor through a sex pilus Figure 27.12 Transformation and Transduction Transformation: Uptake of foreign DNA from the environment Transduction: Viruses carry bacterial DNA from one host cell to another Figure 27.11
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Concept 27.3: Diverse nutritional and metabolic adaptations have evolved in prokaryotes Major Nutritional modes in prokaryotes Table from 27.1 The table contains mode of nutrition, energy source, carbon source, and examples Clicker Question: An autotrophic organism might _______.
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