Transcript Chapter 16
Where we’ve been • To understand one aspect of biology we dig a bit deeper to first learn the parts that make up the whole • To know evolution, you must know something about genetics & heritable traits …before that, you need to understand, cellular reproduction, proteins, & DNA …before that, how a cell works, how a protein comes about, what makes up DNA …membranes, organelles …even down to molecules, atoms, etc. Where we’re going • Evolution & natural selection explains the vast natural diversity of life… all the various organisms that we have Organismal interactions Population Dynamics Communities Biomes Ecosystems Diversity of Life Hierarchy = organizational levels Domain Kingdom Phylum Class Order Family Genus Species Each level is nested within the one above Broad or less specific More specific Closely related species belong to the same genus, similar genera are included in a family, etc… Species that share the same structures, behaviors, etc, can interbreed and produce fertile offspring. • Grouped by shared characters (Evolutionary relationships) – Embryology – Reproduction strategies – Symmetry (body plan) – Morphology – Feeding mode – Etc… Prokaryotes • • • • • Single cell Very small Cell wall Lacks nucleus Lacks membrane bound organelles • Binary fission • Domains: Bacteria and Archaea Organizing prokaryotes • Morphology – E.g. bacilli, cocci, spirocheates • Biochemistry & cell walls – Using stains to determine structural differences – Adaptations to environmental variations • salinity, temperature, pH, O2 levels • Modes of nutrition – Heterotrophic (hetero = other, trophic = food or feeding) • Must consume organic molecules – Autotrophic (self feeding) • Photoautrophic can photosynthesize; get energy from sun • Chemoautotrophic obtain energy from inorganic molecules Bacteria • Share prokaryotic characteristics • Causes some human diseases – Otherwise very important • Decomposers and Nitrogen cyclers Archaea • Extremophiles – Tolerant to extreme environments – Extreme halophiles • High salt concentration – Extreme thermophiles • High and low temperature – Methanogens • Anaerobic environments – Release methane Eukaryotes • • • • • Protista, Fungi, Planatae, Animalia Complex >10x larger DNA in nucleus Cell membrane – Some also have cell wall • Membrane bound organelles – specialization Protista • Very diverse • Single celled & multicellular • Autotrophs – Plant-like • Heterotrophs – Animal-like protozoans – Fungal-like • Aquatic or moist environments • Varies in modes of reproduction, locomotion, & morphology Diplomonads – Spore forming – Two nuclei – Multiple flagella – Usually anaerobic – E.g. Giardia • Intestinal parasite • Contaminates streams • Causes severe diarrhea Trypanosoma • Blood parasite • Single encased flagellum • African tsetse fly – Sleeping sickness • Kissing bugs – Chagas disease Amoeboids • Pseudopodia – extensions of the cell • Locomotion • Feeding • Various environments • Various morphology Ciliates • Cilia to move and feed – E.g. Paramecium, Stentor, Vorticella • Two nuclei types – Macronucleus • Everyday activities – Micronuclei • Sexual reproduction Apicomplexans • Parasites • Apex structures for penetrating host cells • Lack cilia, flagella, or pseudopods • E.g. Plasmodium – Malaria – Enters and feeds on red blood cells – Spread by mosquitos Dinoflagellates • Two flagella in grooves – Spinning flagellates • Phytoplankton – Photosynthesizing aquatic species – Red tides • red pigments along with chl a – Some are toxic • Shell fish accumulation – Bioluminescence Diatoms • Phytoplankton • Silica cell wall – Glass-like – Two halves like a petri plate • Mitotically divide the halves • Secretes the smaller half • Nucleus triggers meiosis when too small Multicellular protists Phaeophyta – Brown algae • E.g. Macrocystis kelp • Rhodophyta – Red algae • Chlorophyta – Green algae • E.g. Ulva, sea lettuce • Lack true stems, leaves, roots as in plants