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About Plant Biology

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About Plant Biology

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About Plant Biology

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  1. About Plant Biology Chapter 1

  2. Why Study Plant Biology? • Show interrelationships between plants and other fields of study • Prepare for careers in plant biology • Gain fundamental knowledge for upper division plant biology courses • Share expertise gained with nonbotanists

  3. What is a Plant? • An organism that is green and photosynthetic • Additional characteristics • Cell wall composed of cellulose • Multicellular body • Can control water loss • Have strengthening tissues • Can reproduce by means of microscopic, drought-resistant spores

  4. Ecologic Services • Sources of food, fabric, shelter, medicine • Produce atmospheric oxygen and organic nitrogen • Build new land • Inhibit erosion • Control atmospheric temperature • Decompose and cycle essential mineral nutrients

  5. Importance of Plants to Human Civilizations • Trees for lumber to make warships • Fuel to smelt metals, cure pottery, generate power and heat • Sources of wealth • spices • Sources of industrial products • Rubber • oil

  6. Natural Plant Losses • Plant losses occurring at a faster rate than ever before • Factors include • Agriculture • Urbanization • Overgrazing • Pollution • Extinction

  7. Environmental Laws • Described in 1961 by plant biologist Barry Commoner • Laws becoming more true every day • Four “environmental laws” • Everything is connected to everything else. • Everything must go somewhere. • Nature knows best. • There is no such thing as a free lunch.

  8. Scientific Method • Codefined and promoted in 17th century by Rene Decartes and Francis Bacon • Steps involved in scientific method • Make observations • Ask questions • Make educated guesses about possible answers • Base predictions on the guesses • Devise ways to test predictions • Draw conclusions

  9. Scientific Method • Hypothesis – “educated guess” based on observations and questioning • Predicted result occurs – hypothesis is most likely correct • Individuals using scientific method should be objective and unbiased

  10. Scientific Method Original Hypothesis Devise method to test hypothesis Analyze results Results support hypothesis Results support hypothesis but suggest minor refinements Results do not support original hypothesis but fall within range that could be expected if original hypothesis is slightly modified Results are so unexpected that they do not support original hypothesis and require a new hypothesis Retest using minor refinements of process Test new hypotheses Test using slightly modified hypothesis

  11. Studying Plants From Different Perspectives • Plant genetics – study of plant heredity • Plant systematics – study of plant evolution and classification • Plant ecology – study of how the environment affects plant organisms • Plant anatomy – study of a plant’s internal structure • Plant morphology – study of how a plant develops from a single cell into its diverse tissues and organs

  12. Study Plants from Taxonomic Classification • Microbiology – study of bacteria • Mycology – study of fungi • Phycology – study of algae • Bryology – study of mosses

  13. Interrelationships Among Several Plant Biology Disciplines Genes ENVIRONMENT Genetics Evolution Taxonomy & Systematics Ecology Paleoecology Biogeography METABOLISM Physiology PLANT TAXONOMIC GROUPS STRUCTURE Phycology Microbiology Mycology Bryology Anatomy DEVELOPMENT Morphology

  14. Plant Classification • Taxonomy • Linnaean system • Easy to use • Based on idea that species never changed • Grouped organisms according to arbitrary similarities • Fails to meet needs of modern biologists

  15. Linnaean Taxa

  16. Plant Classification Whittaker’s Five Kingdoms • Developed in 1969 by Robert Whittaker • Each kingdom assumed to be monophyletic group of species • Molecular biology techniques • Cladistics • Show five kingdom system also does not recognize evolutionary groups

  17. Whittaker’s Five Kingdoms

  18. Plant Classification Cladistics • Based on evolutionary groups • Compare DNA base pair sequences of organisms to determine relatedness • Obtain percent similarity between organisms

  19. Plant Classification • Clades – evolutionary groups • Cladogram = phylogenetic tree • Branching diagram • Emphasizes shared features from common ancestor • Future discoveries may require modifications of cladogram

  20. Plant Classification • Domain • Neutral term • Groups of organisms as large or larger than a kingdom • Monophyletic • Three domains based on cladistics • Eukarya • Bacteria • Archaea

  21. Domain Eukarya • Made up of Whittaker’s plant, animal, and fungal kingdoms • Eukaryotic cells • Membrane-bounded organelles • Linear chromosomes • Protists • Not monophyletic • Controversy over where to place organisms

  22. Domain Bacteria • Organisms originally were placed in Whittaker’s Kingdom Monera • Microscopic • Prokaryotic cells • No membrane-bounded organelles • Circular chromosome • Sexual reproduction unknown • Found in every habitat on Earth

  23. Domain Bacteria Beneficial aspects • Decomposers • Some carry on photosynthesis • Cyanobacteria or blue-green algae • Nitrogen fixation • Convert inorganic N2 into ammonium for plant use • Cyanobacteria

  24. Domain Bacteria Detrimental effects • Pathogens – cause diseases • Human diseases • Botulism, bubonic plague, cholera, syphilis, tetanus, tuberculosis • Plant diseases

  25. Domain Archaea • Organisms originally were placed in Whittaker’s Kingdom Monera • Prokaryotic • Different cell structure and chemistry than organisms in Domain Bacteria

  26. Domain Archaea Divided into three groups based on habitat • Bacteria of sulfur-rich anaerobic hot springs and deep ocean hydrothermal vents • Bacteria of anaerobic swamps and termite intestines • Bacteria of extremely saline waters • Extreme halophiles • Photosynthetic – pigment bacteriorhodopsin

  27. Three Domains

  28. Kingdom Fungi • Eukaryotic cells • Typically microscopic and filamentous • Rigid cell wall made of chitin • Reproduce sexually in a variety of complex life cycles and spores • Widely distributed throughout world – mainly terrestrial

  29. Kingdom Fungi Economic importance • Decomposers • Form associations with roots of plants • Important foods for animals and humans • Mushrooms, morels • Decomposing action of yeast • Flavored cheeses, leavened bread, alcoholic beverages

  30. Kingdom Fungi Economic importance • Production of antibiotics • Penicillium • Pathogens • Invade both plant and animal tissue • Cause illnesses • Reduce crop yields

  31. Kingdom Protista • Eukaryotic cells • Reproduce both sexually and asexually • Catch-all group • Photosynthetic organisms – algae • Nonphotosynthetic organisms – slime molds, foraminiferans, protozoans

  32. Kingdom Protista Algae • Arrangements • Single cells, clusters, filaments, sheets, three-dimensional packets of cells • Photosynthetic • Float in uppermost layers of all oceans and lakes

  33. Kingdom Protista • Phytoplankton • “grasses of the sea” • Microscopic algae • Form base of natural food chain • Produce 50% of all oxygen in atmosphere

  34. Kingdom Plantae • Included all organisms informally called plants • Bodies more complex than bacteria, fungi, or protists • Eukaryotic

  35. Kingdom Plantae • Unique biochemical traits of plants • Cell walls composed of cellulose • Accumulate starch as carbohydrate storage product • Special types of chlorophylls and other pigments

  36. Kingdom Plantae Ecologic and economic importance of plants • Form base of terrestrial food chains • Principal human crops • Provide building materials, clothing, cordage, medicines, and beverages

  37. Challenge for 21st Century While the human population increases, the major challenge of retaining natural biological diversity and developing a sustainable use of the world’s forests, grasslands, and cropland remains. As you study plant biology, think of the ways that you can contribute to this challenge.

  38. Proteins take on a variety of shapes, which enables specific interactions (function) with other molecules. Fig. 2.22 Stages in the formation of a functioning protein

  39. The Plant Cell and the Cell Cycle Chapter 3

  40. Eucaryotic Cell structure • Rough endoplasmic reticulum-site of secreted protein synthesis • Smooth ER-site of fatty acid synthesis • Ribosomes-site of protein synthesis • Golgi apparatus- site of modification and sorting of secreted proteins • Lysosomes-recycling of polymers and organelles • Nucleus-double membrane structure confining the chromosomes • Nucleolus-site of ribosomal RNA synthesis and assembly of ribosomes • Peroxisome-site of fatty acid and amino acid degradation • Flagella/Cilia- involved in motility • Mitochondria-site of oxidative phosphorylation • Chloroplast-site of photosynthesis • Intermediate filaments- involved in cytoskeleton structure

  41. Plant vs Animal Cells • Plant cells have chloroplasts and perform photosynthesis • Outermost barrier in plant cells is the cell wall • Outermost barrier in animal cells is the plasma membrane

  42. Cell • Basic unit of plant structure and function • Robert Hooke • Looked at cork tissue under microscope • “little boxes or cells distinct from one another ….that perfectly enclosed air” • Nehemiah Grew • Recognized leaves as collections of cells filled with fluid and green inclusions