Exam 3 Flashcards
Aristotle
Arranged organisms from simplest to most complex, called scale of nature
da Vinci
Observed that fossils were part of previously existing organisms
de Buffon
Described all known plants and animals - presented evidence that organisms change across generations (not common ancestry)
Carolus Linnaeus
Swedish botanist, physician, and zoologist, who formalized the modern system of nomenclature
By the end of the 18th century
many prominent biologists believed that hereditary changes in populations over long periods of time occurred as a result of inheritance of acquired characteristics; Lamarck believed characters acquired during life were passed on
Evolutionary thought
has mainly developed over the past 150 years
First evolutionary revolution
Charles Darwin, Origin of Species, 1859
Second evolutionary revolution
1930s. Theories of Darwin’s natural selection, Mendelian genetics, and population genetics intersected to provide better understanding of mechanisms of evolution.
Third evolutionary revolution
Now with molecular genetics
Molecular genetics
Regulatory genes that act as developmental switches. Organisms with similar genomes can look very different because different developmental programs were used to create them.
Charles Darwin
Unpaid naturalists on voyage 1831-1836. Read geology book that theorized an old earth. Collected plants and animals. Guided by Malthus’ ideas that populations grow geometrically until resources limit growth. Presented joint paper on natural selection in 1858.
Homology
A characteristic shared by different organisms
Convergent evolution
Similarities not due to common ancestry
Darwin observed
Artificial selection, limited food supply, variation in competitive abilities, comparative anatomy and embryology
Darwin reasoned
Individuals best adapted to utilize available resources would increase in number in succeeding generations
Artificial selection
Changes in populations of domestic animals by retaining animals with desirable traits
Natural selection
Descent with modification
Mutation
Change in a gene or chromosome. Most are harmful. Some are silent. Result in loss of information.
Deletion
Part of a chromosome breaks off
Translocation
Piece of chromosome becomes attached to another
Inversion
Part of chromosome breaks off and then reattaches in an inverted position
Punctuated equilibrium
Major changes occur in spurts followed by many years with minor change, based on the large gaps in the fossil record.
Geographic isolation
Isolation of two populations prevents gene flow
Ecological isolation
Ecological factors such as climate or soils may play role in isolation, resulting in sympatric species that occupy overlapping ranges of territories and do not exchange genes
Mechanical isolation
cannot cross-breed. Ex.: pollinia of orchids
Hybrids
Offspring produced by parents that differ in one or more characteristics. Two related species. Hybrids often sterile because chromosomes do not pair properly at meiosis. Sterile hybrids may reproduce asexually
Introgression
Intercrossing between hybrids and parents
Polyploidy
Occurrence of double the normal chromosome number
Apomixis
Production of seeds without fertilization
Theophrastus
Organized and classified plants based on leaf characteristics
Carolus Linnaeus
Established binomial system of nomenclature. Published Species Plantarum in 1753
Six Kingdoms
Archaea, Bacteria, Protista, Fungi, Plantae, Animalia
Morphological species concept
A species is defined by morphology
Interbreeding species concept
A species is a population capable of interbreeding and is reproductively isolated from other groups
Ecological species concept
A species is a group of related individuals that occupy a unique ecological niche
Cladistic species concept
A species is determined by phylogenetic history
Parsimony
Best relationship model that can be contrived. Occam’s razor - “One should not make more assumptions than the minimum needed to explain anything.”
Eclectic species concept
States that a single criterion is not sufficient to identify species
Nominalistic species concept
Species do not exist.
Domain Archaea
Kingdom Archaea, Phylum Archaebacteria
Domain Bacteria
Kingdom Bacteria, Phylum Eubacteria
Phylum Eubacteria
Class Eubacteriae, Cyanobacteriae, and Chloroxybacteriae
Archaea and Bacteria Common Features
Prokaryotic. Primarily absorb nutrients through cell wall, sometimes by chemical reactions or photosynthesis. Reproduction by fission, none sexual (genetic recombination by pili or close contact of cells).
Cell Details and Reproduction
Folds of membrane perform organelle-like function. Ribosomes half the size of eukaryotic cells. Nucleoid region. 30-100 DNA plasmids present.
Nucleoid
Single chromosome in form of ring
Plasmids
Small circular DNA molecules that replicate independently of chromosome. Entire group of them consists of multiple copies of one or a few different DNA molecules.
Fission
2 copies of duplicated chromosomes migrate to the opposite ends of the cell. Perpendicular walls and cell membranes formed in middle of cell. The 2 new cells separate and enlarge to original size. May undergo fission every 10-20 mins under ideal conditions (until food depleted and waste built up).
Genetic Recombination in Bacteria
Conjugation, Transformation, and Transduction
Conjugation
DNA transferred from donor cell to recipient cell usually through pilus (pl. pili)
Transformation
Living cell acquires DNA fragments released by dead cells.
Transduction
DNA fragments carried from one cell to another by viruses.
Size of bacteria
Mostly les than 2 or 3 micrometers in diameter
Three forms of Bacteria
Cocci (spherical or elliptical), Bacilli (rod-shaped or cylindrical), and Spirilla (helix or spiral)
Bacteria also classified by
Sheath around cells, hair-like or bud-like appendages, endospores, pili or flagella, color, mechanisms of movement, biochemical characteristics, reaction of cell walls to dye (gram-positive or gram-negative)
Kingdom Archaea characteristics
Metabolism is fundamentally different from other bacteria. Differ from true bacteria by unique sequences of bases in RNA, lack of muramic acid in walls, and by production of distinct lipids.
Methane bacteria
Killed by oxygen. Active only under anaerobic conditions. E derived from generation of methane gas from carbon dioxide and hydrogen.
Halophilic (Salt bacteria)
Metabolism enables these bacteria to thrive under extreme salinity. Carry out simple photosynthesis with aid of bacterial rhodopsin
Thermophilic (Sulfolobus bacteria)
Occur in sulfur hot springs. Metabolism allows them to thrive at high temps (close to boiling). Shape of ribosomes and chemistry of sulfolobus bacteria distinguishes them from other archaebacteria, true bacteria, and eukaryotes.
Human relevance of Archaebacteria
Methane bacteria produce methane gas that can be used as clean energy, produced on large-scale when organic wastes fed into methane digester. Leftover sludge can be used as fertilizer
Kingdom Bacteria characteristics
Muramic acid in cell walls, different RNA bases, metabolism, and lipids than archaebacteria
Class Eubacteriae
Unpigmented, purple, and green sulfur bacteria. Mostly heterotrophic saprobes. some parasitic, some autotrophic. Photosynthetic without producing oxygen
Saprobes
Feed from nonliving organic matter. Responsible for decay and recycling of organic matter in soil.
Autotrophic bacteria
Synthesize organic compounds from simple inorganic substances
Purple sulfur bacteria
Bacteriochlorophyll pigments, use hydrogen sulfide (instead of water)
Purple nonsulfur bacteria
Bacteriochlorophyll pigments, use hydrogen
Green sulfur bacteria
Chlorobium chlorophyll pigments, use hydrogen sulfide
Class Cyanobacteria
Photosynthetic and produce oxygen
Class Chloroxybacteria
Photosynthetic and produce oxygen
Human relevance of sulfur bacteria
Composting, cause disease
Koch’s postulates
Rules for proving a particular microorganism is cause of a particular disease: must be present in all cases, isolated from victim, able to infect host, reisolated from infected host
True bacteria useful
Biological control, bioremediation (clean up toxic waste and pollution)
Cyanobacteria characteristics
Chlorophyll a. Produce oxygen. Contain phycobilins. Fix nitrogen.
Cyanobacteria distribution
in diverse variety of habitats - polluted pools and ditches. Fresh and marine water. Various temps. First to return after volcanic eruption. Symbiotic with other organisms
Cyanobacteria Form, Metabolism
Chains or colonies through gelatinous sheaths. Blue-green in half species. Produce nitrogenous food reserve (cyanophycin). Flagella not observed
Cyanobacteria Reproduction
New cells by fission. In Nostoc and Anabaena, fragmentation occurs at heterocyst. Also produce akinetes
Heterocyst
Large colorless, nitrogen-fixing cell
Akinetes
Thick-walled cells that resist adverse conditions
Human relevance of cyanobacteria
Bottom of various food chains. Abundant in fresh water in warmer months (poisonous algal blooms), food, nitrogen fixation
Class Chloroxybacteriae - Prochlorobacteria
Have chlorophyll a and b of higher plants, but no phycobilin accessory pigments. Some propose chloroplasts evolved from them. Cell structure similar to cyanobacteria and true bacteria.
Domain Eukarya
All members have eukaryotic cells. Includes kingdoms protista, plantae, fungi, and animalia
Protista features
Heterogeneous. Nutrition varied, life cycles vary, reproduction varies. Algae are in this kingdom
Phylum Chlorophyta: Green algae
Unicellular or multicellular. Greatest variety in freshwater. Chlorophylls a and b. Store food as starch. Most single nucleus. Most both asexual and sexual reproduction
Acetabularia
Mermaid’s wineglass. Consists of a large single cell, shaped like a delicate mushroom. Used in classic experiments demonstrating influence of nucleus on form of cell
Phylum Chromophyta
The diatoms. Unicellular. Fresh and salt water, particularly cold marine habitats. Also dominate algal flora on damp cliffs, tree bark, or buildings. Look like ornate glass boxes with lids - as much as 95% of wall is silica; used for testing resolution of microscopes. Chlorophylls a and c. Food reserves oils, fats, or laminarin
Diatom reproduction
Asexual results in half of cells becoming progressively smaller. Original cell size restored through sexual reproduction
Phylum Chromophyta
Brown algae (Phaeophyceae). Relatively large; none unicellular or colonial. Mostly marine; majority in cold, shallow water (max depth 900 ft.) Many have a thallus differentiated into a holdfast, a stipe, and blades. Blades may have gas-filled bladders. Chlorophylls a and c. Found in the Sargasso Sea
Phylum Rhodophyta
The red algae. In warmer and deeper waters than brown algae. Most filamentous. Range 656-884 ft. Receives 0.0005% of max sunlight.
Red Algae
Colors due mostly to phycobilins similar to those of cyanobacteria. Chlorophylls a and sometimes d. Food reserve - Floridean starch. Numbers of species used to produce agar.
Phylum Euglenophyta
No cell wall. Pellicle. Flagellum pulls cell through water. Gullet ingests food. About 1/3 species have disc-shaped chloroplasts. Red eyespot for light detection. Paramylon food reserve. Asexual reproduction by cell division. Sexual reproduction not confirmed.
Pellicle
Plasma membrane and underlying strips that spiral around cell
Phylum Dinophyta
Red tides. Cellulose armor plates in cell membrane. Two flagella in intersecting grooves (rudder and spinning motion). Most have disc shaped chloroplasts - contain chlorophyll a and c with xanthophyll pigments, though 45% are non photosynthetic.
Red tides
Some dinoflagellates produce neurotoxins that accumulate in shell fish
Human Relevance of Algae
Bottom of food chain. Diatoms: oils are vitamin sources; diatomaceous earth - filtration, polishes (toothpaste), paint that reflects light. Chlorella: potential human food source. Algin: produced by giant kelps and other brown algae - ice cream, salad dressing, latex paint, textiles, ceramics, regulating water behavior (ice development, penetration of water, suspension-stabilizing). Minerals and food: Iodine from kelp; red algae (dulse, nori; Carrageenan thickening agent - chocolate milk). Agar: produced by red alga gelidium - solidifier of nutrient culture media; retains moisture in bakery products; base for cosmetics; medication capsules.
Hyphae
Individual threads produced by fungi
Mycelium
Mass of hyphae
True fungi
All are filamentous or unicellular heterotrophs. Chitin in cell walls. Most lack motile cells. Filamentous except some Chytrids and all yeasts
Phylum Chytridiomycota
Chytrids. Simple. Mostly one-celled aquatic organisms. Some are parasitic, others are saprobic. Some short hyphae or mycelia that is coenocytic. Many reproduce only asexually through the production of zoospores within a spherical cell. Sexual reproduction by fusion of haploid gametes. Zygote undergoes meiosis and is often a resting spore.
Saprobic
Feed on nonliving organic material
Coenocytic
Without cross walls
Phylum Zygomycota
Black bread molds. Rhizopus - well known and found everywhere. Coenocytic hyphae with numerous haploid nuclei. Asexual reproduction: sporangiophores grow upright and produce sporangia at tips; black spores formed in sporangia.
Phylum Zygomycota Sexual reproduction
Conjugation. Progametangia on hyphae of different mating strains become gametangia, which merge and become multinucleate coenozygote when nuclei of two strains fuse in pairs. Thick wall forms around coenozygote - zygosporangium containing numerous diploid nuclei. Meiosis forms spores in sporangia on sporangiophores
Human relevance of Zygomycota
Food sources: tempeh in Indonesia. Industrial uses: pharmaceuticals (manufacture of anesthetics), pigments (yellow pigment for coloring margarine)
Phylum Ascomycota
Includes yeasts, powdery mildews, ergot, truffles, and morels. Most produce mycelia with hyphae partitioned into individual cylindrical cells. Asexual reproduction: single or chains of conidia produced at tips of hyphae called conidiophores. Budding - yeasts. Also perform sexual reproduction - n+n stage.
Human relevance of Ascomycota
Food: morels and truffles; yeast - fermentation produces ethyl alcohol, CO2 causes dough to rise and makes it porous; ergot fungus may infect rye and other grains - ergotism may occur in those who eat the contaminated bread, ergot drugs are medicinally useful in small doses. Plant diseases.
Phylum Basidiomycota
Includes mushrooms, toadstools, puffballs, shelf fungi, rusts, smuts, and jelly fungi. Hyphae individual cells. Asexual reproduction is infrequent. Each cell of hyphae contains a single haploid nucleus - monokaryotic hyphae
Basidiomycete sexual reproduction
Hyphae of individual mating types unite and initiate a new mycelium, called dikaryotic hyphae, in which each cell has one nucleus from each original mating type
Fairy rings
Dikaryotic hyphae of Basidiomycota radiate out from starting point, producing basidiomata
Boletes
Produce spores on surface of pores instead of gills
Shelf fungi
Grow horizontally from bark or dead wood
Puffballs
Spores released from pore at top
Bird’s nest fungi
Egglike bodies contain basidiospores
Parasitic basidiomycetes that do not form basidiomata
Smuts of grain crops, where mycelium absorbs nutrients from host cells and they secrete substances that stimulate host cells to form tumors. Rusts which attack a variety of plants. Black stem rust requires two hosts.
Human relevance of the club fungi
Can be poisonous (less than 75 of the approx. 25000 species), food - shiitake mushrooms (high in protein, Ca, P, and Fe), portabella mushrooms. Pharmaceutical extracts. Nutrient recycling in soil.
Phylum Deuteromycota
Fungi for which a sexual stage has not been observed. Grouped together in an artificial phylum. Most commonly reproduce by conidia
Human relevance of Deuteromycetes
Penicillium - antibiotics and gourmet cheese. Aspergillus - citric acid, soy sauce, miso, artificial flavoring, photographic developers, dyes, aspergilloses (respiratory disease), athlete’s foot, aflatoxin (carcinogen)
Lichens
Consist of a fungus and a photosynthetic organism associated in a spongy thallus. Photosynthetic component supplies food, fungus protects the photosynthetic organism from harmful light intensities and absorbs and retains water and minerals. Three genera of green algae and one genus of cyanobacterium involved in 90% of all lichen species. Each lichen has own unique species of fungus, usually a sac fungus. Lichen species are identified according to their fungus.
Lichens growth
Slow and long-living. Gelatinous substance in thallus allows them to withstand alternating wet and dry periods. Usually have three or four layers: Upper cortex, algal layer, medulla, lower cortex
Crustose
Lichens attached to or embedded in substrate over entire lower surface
Foliose
Lichens containing leaf-like thalli which often overlap
Fruticose
Lichens resembling miniature upright shrubs or hang down in festoons from branches.
Human relevance of lichens
Exceptionally sensitive to pollution (sulfur dioxide and nuclear radiation pollution indicators). Degrade historic structures. Food supplements: antibiotic properties and dyes. Food for animals - reindeer eat lichen.
Bryophytes
Kingdom Plantae. Phylum Hepaticophyta, Phylum Anthocerophyta, Phylum Bryophyta
Plants and Green Algae common traits
Chlorophylls a and b, carotenoids. Starch food reserve, cellulose in cell walls. Phragmoplast and cell plate during cell division
Plants only
Surfaces have fatty cuticle. Gametangia and sporangia are multicellular. Zygotes - multicellular embryos within parental tissues that originally surrounded egg
Bryophytes Specifics
About 23,000 species including mosses, liverworts, and hornworts. Occupy wide range of habitats: damp banks, trees, logs; bare rocks in scorching sun; frozen alpine slopes. In elevations from sea level up to 18,000 ft. +
Bryophyte characteristics
Often have mycorrhizal fungi. None have true xylem or phloem; many have hydroids for water conduction, most water is absorbed directly through the surface, and a few have leptoids for food-conduction. Require water to reproduce sexually. Exhibit alternation of generations. Three distinct phyla - none appear similar to other living plants.
Phylum Hepaticophyta
Liverworts. Structure and form: most common and widespread liverworts have flattened lobed thalli that develop from spores. Spores that germinate may produce protonema. In thalloid liverworts, growth is prostrate and one-celled rhizoids on the lower surface anchor plant.
Best known liverwort
in genus Marchantia. Thallus forks dichotomously as it grows. Bottom layer of thallus - epidermis from which rhizoids and scales arise. Upper surface is divided into diamond-shaped segments that mark the limits of chambers below. Each segment has small bordered pore opening. Short erect rows of cells with chloroplasts sit on floor of chambers.
Liverworts reproduction
Gametangia formed on gametophores. Female - archegoniophore. Archegonia with eggs hang beneath archegoniophore. Elater - sensitive to humidity and aids in spore dispersal
Phylum Anthocerophyta
Hornworts. Structure and form: mature sporophytes look like miniature greenish-blackish rods (horns). Gametophytes thalloid - cells with only one large chloroplast, thalli have pores and cavities filled with mucilage that often contain nitrogen-fixing bacteria. Only about 100 species worldwide. Asexual reproduction by fragmentation of thallus
Hornwort Reproduction
Fragmentation. Sexual: archegonia and antheridia produced in rows just beneath upper surfaces of gametophytes. Sporophyte: with numerous stomata; meristem above foot continually increases length of sporophyte from base; meiosis occurs in sporophyte to produce spores; diploid elaters that function similar to those of liverworts, intermingled with spores.
Phylum Bryophyta
Mosses. About 15,000 species of mosses currently known. Divided into 3 classes: peat moss, true moss, and rock moss. Leaves of gametophytes have blades nearly one-cell thick except at midrib - never lobed or divided. Cells usually contain numerous chloroplasts. Peat moss leaves have large transparent cells without chloroplasts that absorb water; and small, green photosynthetic cells sandwiched between. Axis stemlike without xylem or phloem. Often with central strand of hydroids
Bryophyta reproduction Structures
Gametangia at apices of leafy shoots. Archegonium is cylindrical with egg in swollen base and neck above containing narrow canal. Multicellular filaments called paraphyses scattered among archegonia. Antheridia on short stalks, surrounded by walls one cell thick. Sperm cells, each with pair of flagella, formed inside. Sperm forced out top. Paraphyses scattered among antheridia.
Bryophyta reproduction
Archegonia release substances that attract sperm. Sperm swim down neck of archegonium. Zygote grows into spindle-shaped embryo. Top of archegonium splits off and forms cap on top of sporophyte, called the calyptra. Mature sporophyte consists of capsule, seta, and foot. Meiosis produces spores inside capsule. Peristome, composed on one or two rows of teeth under operculum at tip of capsule opens or closes in response to humidity. Spores develop into filamentous protonema that produces buds that develop into leafy gametophytes.
Relevance of Bryophytes
Pioneer species on bare rock. Accumulate mineral and organic matter used by other organisms. Retain moisture and reduce flooding and erosion. Indicators of presence of surface water. Packing material. Peat mosses most important bryophyte to humans. Soil conditioner - high absorptive capacity. Poultice material - antiseptic properties and absorbency. Fuel.
Ferns
Phylum Psilotophyta, Phylum Lycophyta, Phylum Equisetophyta, Phylum Polypodiophyta
Psilotophyta - Whisk Ferns
Resemble small green whisk brooms. Sporophytes: dichotomously forking stems from rhizomes; neither roots nor leaves; enations along stems. Sporangia fused in threes and produced at tips of short branches. Gametophytes develop from spores beneath ground.
Lycophyta - Ground Pines, Spike Mosses, and Quillworts
Two major living genera - Lycopodium and Selaginella. Reproduction: in sporangia, sporocytes undergo meiosis, producing spores. Spores grow into independent gametophytes. Archegonia and antheridia produced on gametophytes. Sperm flagellated; water essential for fertilization
Selaginella - Phylum Lycophyta
Produce two different type of gametophytes - heterospory. Microsporophylls bear microsporangia containing microsporocytes (male). Megasporophylls bear megasporangia containing megasporocytes.
Isoetes - Quillworts - Phylum Lycophyta
Most found in areas partially submerged in water for part of the year. Microphylls are arranged in a tight spiral on a stubby stem. Ligules occur towards leaf bases. Corms have vascular cambium. Plants generally less than 10 cm tall.
Phylum Equisetophyta - the Horsetails and Scouring Rushes
Equisetum. Branched and unbranched forms, usually less than 1.3 meters tall. Stems jointed and ribbed; stomata in grooves between ribs. Silica deposits on walls of stem epidermal cells.
Equisetum reproduction
Asexual fragmentation of rhizomes. Sexual reproduction: strobili at tips of stems with sporangia connected to sporangiophores; spores green with 4 ribbon-like elaters attached, aiding in spore dispersal; gametophytes lobed, green, cushion-like, up to 8 mm in diameter.
Polypodiophyta - the Ferns
Vary in size from less than 1 cm to 25 m tall. Leaves are megaphylls, referred to as fronds. Require external water for reproduction.
Polypodiophyta Sporophyte stage
Sporophyte is conspicuous phase. Fronds, rhizomes, roots. Fronds appear coiled in crozier and then unroll and expand. They are often divided into segments called pinnae.
Polypodiophyta reproduction
Sporangia stalked. Sori may be protected by indusia. With rows of heavy-walled brownish cells. Meiosis forms spores in sporangia. Spores released and grow into gametophytes called prothalli. Zygote develops into sporophyte.
Human relevance of Ferns
House plants (filter air), outdoor ornamentals, cooked rhizomes as food, folk medicine, fronds used in thatching for houses, basketry and weaving.
