Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Phylogeny & Domain Bacteria Lectures by Erin Barley Kathleen Fitzpatrick © 2011 Pearson Education, Inc. Taxonomy • how organisms are named and classified • Greek philosophers suggested that life might have changed gradually over time – but Aristotle – viewed species as fixed and said that life-forms could be arranged on a ladder of increasing complexity = scalae naturae Taxonomy • Carolus Linneaus – developed the binomial system for naming species – binomial = two names • developed a nested classification system in contrast to Aristotle – grouped animals according to similar characteristics – groups (taxa) known as phylum, class, order, family, genus, species – thought the similarities were due to God’s creation Human being = Homo sapiens -first word = Genus -second word = species name -both are usually italicized Phylogeny vs. Taxonomy • taxonomical classification not only takes the morphological similarities of organisms into account – it also looks at the evolutionary relationships • evolutionary history of a species or a group of species = phylogeny • phylogenies are constructed uses data ranging from fossils to genetic analysis to derive evolutionary relationships – each branch point is a divergence of two evolutionary lineages from a common ancestor Genus Family Panthera Mephitis Lutra lutra Canis Canis pardus mephitis (European familiaris lupus (leopard) (striped skunk) otter) (domestic dog) (wolf) Panthera Felidae Order • classification using phylogeny depends upon identifying common ancestors • physical and genetic similarities due to shared ancestry = homology • the relationship between common ancestors and their descendants can be shown as a phylogenetic tree • the common ancestor is the base of a dichotomy or a two-way branch point Species Phylogeny Mephitis Lutra Mustelidae Carnivora Canis Canidae 65.5 251 Mesozoic Cenozoic Millions of years ago 542 Paleozoic Neoproterozoic • common ancestor of the fish and the human arose 542 MYA!! • so there has been 542 million years of evolution for both the fish and the human From Kingdoms to Domains • earliest taxonomists just had two kingdoms: Plants and Animals • with the discovery of bacteria – things got a bit more complicated – bacteria were classified as plants since they were found to have a cell wall • since algae underwent photosynthesis – considered plants also • fungi also classified as plants – despite having nothing in common with plants • organisms that consumed were considered animals – including single celled organisms like protozoans • in 1969: five-kingdom classification system – Robert Whittaker – recognized the existence of two fundamental cell types: prokaryotes and eukaryotes – created a separate kingdom for prokaryotes and divided up the eukaryotes – 1. Monera - prokaryotic – 2. Protista – unicellular organisms including algae – 3. Fungi – 4. Plantae – 5. Animalia – based on the nutritional requirements and methods of these domains • plants = autotrophs • animals = heterotrophs & internal digestors • fungus = decomposers & heterotrophs • this classification scheme has changed – due to analysis of genes 0 • adoption of a three domain system of superkingdoms • contains the “old” kingdoms of protists, fungi, plants and animals • these kingdoms no longer exist but are still kept by us stubborn biologists! 1 Billion years ago – 1. Bacteria – most of the currently known prokaryotes (or Eubacteria) – 2. Archaea – prokaryotes that inhabit a wide variety of environments – 3. Eukarya - eukaryotes Bacteria Eukarya gene transfer 2 3 common ancestor of all life 4 Origin of life Archaea Comparing Prokaryotic and Eukaryotic Cells • Prokaryotic cells: – no nucleus – DNA in a region of the cytoplasm called the nucleoid – no membrane-bound organelles – a Cytoplasm bound by the plasma membrane – smaller ribosomes • Eukaryotic cells – membrane – bound nucleus containing DNA – membrane-bound organelles – a Cytoplasm in the region between the plasma membrane and nucleus – larger ribosomes Prokaryotic Cells • usually smaller and less complex than eukaryotic cells • first cells to evolve • single-celled organisms – 0.5 to 5um in diameter (eukaryotes 10-100um) – some species exist as aggregates called colonies • e.g. cyanobacteria • defined as having no nuclear membrane, no mitochondria or other organelles • divided into two domains: – Bacteria – Archaea Domain Bacteria • Bacteria: – collective biomass – 10x of all eukaryotes – vast genetic diversity among members – physical diversity • shapes: spheres (coccus), rods (bacilli) and spirals 1 µm Spherical (cocci) 2 µm Rod-shaped (bacilli) 5 µm Spiral Bacteria Fimbriae Nucleoid • made up of numerous components: – cell capsule (slime layer) – for adherence and protection – cell wall – plasma membrane – phospholipid bilayer – fimbrae – for attachment & conjugation – flagella(e) – for locomotion – cytoplasm – for metabolism – nucleoid region with a single chromosome – ribosomes – for protein synthesis Ribosomes Plasma membrane Bacterial chromosome Cell wall Capsule (a) A typical rod-shaped bacterium Flagella Prokaryotic Cells • Bacterial cell components: – cell wall – rigid structure outside the plasma membrane • cross-linked sugars • for protection, structural support & reproduction • gram negative bacteria have an additional layer of sugars and fats outside the cell wall • this layer is responsible for the toxicity of these bacteria Prokaryotic Cells Fimbriae Nucleoid • Bacterial cell components: – fimbrae – structures involved in attachment Ribosomes Plasma membrane Bacterial chromosome • shorter ones involved in reproduction = pilus – flagella – made of protein filaments • for locomotion – cytoplasm – intracellular fluid of the prokaryote • bounded by the plasma membrane • cytosol + cytoskeleton • no membrane-bound organelles Cell wall Capsule (a) A typical rod-shaped bacterium Flagella