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Genetic Material Transfer: Bacterial Transformation, Conjugation, and Transduction - Prof., Study notes of Biology

University of North Carolina (UNC) - WilmingtonBiology
Prof. Frederick S. Scharf

An overview of various processes by which genetic material is transferred between bacteria, including conjugation through pili, transformation through uptake of dna fragments, and transduction through viruses. Additionally, it covers the classification of bacteria based on their nutritional requirements and the concept of convergent evolution in purple bacteria.

Typology: Study notes

2013/2014

Uploaded on 04/03/2014

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Bacterial Reproduction 4/3/14 12:33 PM
Binary Fission: One cell divides into two
Tradeoff: negative correlation between two traits
• Advantage: rapid population growth when environmental conditions
are favorable
• Disadvantage: no genetic variation in asexual organisms
Why is pop. growth so rapid?
• Do not produce gametes or zygotes, and do not undergo meiosis
Three Forms of Genetic Recombination:
• Conjugation
o DNA transferred from donor cell to recipient cell usually
through pilus (pleural: pili)
• Transformation
o Living cell acquires DNA fragments released by dead cells
• Transduction
o DNA fragments carried form one cell to another by viruses
Akinete: large, thick walled, sugar filled celled; what’s the purpose?
Heterocyte: fix atmospheric N2 into forms that can be used by organism
Endospores: DNA and other materials in tough coat.
Bacterial Diversity
• Fossils of bacteria – 3.5 billion years old
• Fossils of first eukaryotic cells- 1.3 billion years old
• 5,000 species of bacteria recognized today.
o Each species found in astronomical numbers
! But, difficult to classify simple once-celled organism,
thus number of bacteria species uncertain.
! Strains of one species look alike. –subset of a bacterial
species that differs from others of that species by some
identifiable characteristic.
! Clustered by what they do
pf3
pf4
pf5
pf8
pf9
pfa
pfd
pfe
pff
pf12
pf13
pf14

Partial preview of the text

Download Genetic Material Transfer: Bacterial Transformation, Conjugation, and Transduction - Prof. and more Study notes Biology in PDF only on Docsity!

Bacterial Reproduction 4/3/14 12:33 PM

Binary Fission: One cell divides into two Tradeoff: negative correlation between two traits

  • Advantage: rapid population growth when environmental conditions are favorable
  • Disadvantage: no genetic variation in asexual organisms Why is pop. growth so rapid?
  • Do not produce gametes or zygotes, and do not undergo meiosis Three Forms of Genetic Recombination:
  • Conjugation o DNA transferred from donor cell to recipient cell usually through pilus (pleural: pili)
  • Transformation o Living cell acquires DNA fragments released by dead cells
  • Transduction o DNA fragments carried form one cell to another by viruses Akinete: large, thick walled, sugar filled celled; what’s the purpose? Heterocyte: fix atmospheric N2 into forms that can be used by organism Endospores: DNA and other materials in tough coat. Bacterial Diversity
  • Fossils of bacteria – 3.5 billion years old
  • Fossils of first eukaryotic cells- 1.3 billion years old
  • 5,000 species of bacteria recognized today. o Each species found in astronomical numbers ! But, difficult to classify simple once-celled organism, thus number of bacteria species uncertain. ! Strains of one species look alike. – subset of a bacterial species that differs from others of that species by some identifiable characteristic. ! Clustered by what they do

Classification of Bacteria: Nutrition

  • Autotrophs o Produce all or most of their own organic compounds
  • Photoautotroph o Use light as energy source for synthesis of organic compounds from CO2 and H2O, H2S, H
  • Chemoautotrophs o Use energy obtained from chemical modification of inorganic compounds to synthesize organic compounds and CO
  • Heterotrophs o Use organic carbon for growth by consuming other organisms Phylum Proteobacteria : Convergent Evolution
  • ‘purple bacteria and their relatives” o Some are heterotropic – cannot synthesizes their own food ! Majority saprobes - food from nonliving organic matter " Responsible fore decay and recycling of organic matter in soil.
  • Purple bacteria are photosynthetic
  • Some are chemoautotrophs
  • Some are mutualists (Rhizobium) o Associates with legume roots and fixes N The Cyanobacteria (Blue-Green Bacteria)
  • Fresh and marine water, but not acidic water. o Principal photosynthetic organisms in plankton – organisms in the water column that can’t swim against a current.
  • Water of various temperatures- Hot springs at Yellowstone National Park. o Lichen- mutualism between a fungus and a photosynthetic organism ! Fungus benefits from sugars from photosynthesis, Cyanobacteria receives shelter Aerobic photosynthesis: 6CO2 + 12H2O # C6H12O6 + 6O2 + 6H2O
  • Cyanobacteria, chloroplast, and oxygen o Thought that chloroplasts originated as cyanobacteria or prochlorobacteria living within other cells. o Fossils of cyanobacteria, 3.5 billion years old, found in Australia. o 3 Billion years ago, cyanobacteria produced oxygen as by- product of photosynthesis o Oxygen accumulated in atmosphere, becoming substantial 1 Billion years ago. o As oxygen accumulated, other photosynthetic organisms appeared and forms of aerobic respiration developed. o In last half billion years enough ozone for UV shield and for photosynthetic organisms to survive on land.
  • Human relevance of the cyanobacteria: o Cyanobacteria are among the many aquatic and photosynthetic organism at the bottom of various food chains. o Often become abundant in bodies of fresh water in warmer months. ! Algal blooms " Can be poisonous to livestock. o Food- Spirulina with significant vitamin content o Swimmers itch o Nitrogen fixation Viruses (Not considered living!)
  • Size and structure: about size of large molecules, 15-300 nm o Represent interface between biochemistry and life ! Do not grow by increasing in size or dividing ! Do not respond to external stimuli ! Cannot move on their own ! Cannot carry on independent metabolism ! Inside living cells, they express their genes and use cellular machinery to produce more virus particles.
  • Size and structure: o Consists of nucleic acid core surrounded by protein coat. o Architecture of protein coat varies.

! 20 sided, or head and tail. o Core consists of DNA or RNA, not both. o Classified according to DNA or RNA ! Then according to size and shape, nature of protein coats, and number of identical structural units in their cores. o Bacteriophages- Viruses that attack bacteria

  • Viral reproduction: o Viruses replicate at expense of their host cells. ! Attach to susceptible cell ! Penetrate to cell interior ! DNA or RNA dictates synthesis of new molecules. ! New viruses released from host cell " Host cell dies ! Some can mutate very rapidly. " As a result, new vaccines need to be developed.
  • Human relevance of viruses: o Annual loss in work time due to common cold and influenza viruses alone amount to million of hours. ! Immunizations have dramatically decreased incidences of many viral diseases such as chicken pox, German measles, and mumps. o Aids ! Retrovirus: a virus with two identical nuclear strands. " Evolves extremely quickly - About a million times faster than cellular organisms. o RNA makes DNA makes RNA makes protein. o Used to infect disease organism of animals and plants ! Ticks, insects, possibly gypsy moths. Viroids and Prions
  • Viroids: circular strands of RNA that occur in nuclei of infected plant cells. o Transmitted from plant to plant via pollen, ovules, or machinery

Protists 4/3/14 12:33 PM

Outline:

  • Features of the kingdom Protista
  • Evolution and relationships o “Supergroups” ! Excavata ! Alveolates ! Rhizaria ! Amoebozoa ! Reproductive adaptions What is a protist?
  • Most are unicellular
  • Bound organelles (mitochondria, chloroplasts) – Eukaryotic
  • Heterotrophic, autotrophic, mixotrophic (both heterotrophic, and autotrophic) , Osmotrophic: absorption of nutrients through osmosis.
  • Aquatic
  • Mitosis to asexually reproduce (some can,some cannot)
  • Meiosis to make gametes o Some can do both Evolutionary Relationships Taxonomic garbage dump: organisms that are not classified in plants, animals, or fungal groups.
  • Protists are not monophyletic Classified by ecological role
  • 3 major groups o Algae: generally phototrophs o Protozoa: heterotrophic (proto-first # first animals) o Fungus-like: resemble fungus and obtain nutrition through absorbing nutrients
  • Groupings lack taxonomic or evolutionary meaning. Classified by habitat
  • Plankton: swimming or floating
  • Phytoplankton: photosynthetic
  • Zooplankton: heterotrophic
  • Periphyton: microorganisms that attach by mucilage to surfaces underwater (rocks, sand, plants, algae)
  • Macroalgae: photosynthetic protists # large enough to see with naked eye (example: Kelp) Classified by motility
  • Swim using eukaryotic flagella o Flagellates o Some flagellated reproductive cells
  • Cilia- shorter and more abundant than flagella o Ciliates
  • Amoeboid movement – using pseudopodia o Amoebae
  • Gliding on protein or carbohydrate slime Supergroup Excavata
  • Related to some of Earth’s earliest eukaryotes
  • Named for a feeding groove “excavated” into the cells of many representatives.
  • Food particles are taken into cells by phagotrophy – ingestion of solid particles across the cell membrane o Endocytosis (processes by which cells absorb molecules) and evolutionary basis for endosymbiosis.
  • Some are parasites o Trichomonas vaginalis (spread sexually, asymptomatic, most common std) – parasitic protist ! o Giardia lamblia (by drinking contaminated water # diarrhea ) Green Algae (closest relatives to land plants) Define primary plastids and secondary plastids Characteristics:
  • Marine or freshwater, unicellular, colonial, multicellular
  • Apicomplexa o Medically important parasites o Plasmodium
  • Dinozoa Dinoflagellates – some photosynthetic, others not Red tide and mutualistic relationship with coral. – Pfiesteria (harmful algal blooms)
  • Named for saclike membranous vesicle (alveoli) present in cell periphery. Parasitic protist life cycle
  • Parastitic protists often use more than one host organism, in which different life stages occur.
  • Malarial parasite Plasmodium alternate between the humans and Anopheles mosquitoes.
  • Different stages in different host tissues. Supergroup Strameopila
  • Wide range of algae, protozoa, and fungus-like protists (Phaeophyta
  • brown algae)
  • Usually produce flagellate cells at some point
  • Named for distinctive straw-like hairs on the surface flagella
  • Heterotrophic or photosynthetic o Plastids from secondary endosymbiosis with red algae. Supergroup Rhizaria
  • Have thin, hair like extension of the cytoplasm called filose pseudopia
  • Phylum Chlorarachiniophyta – tropical algae
  • Phylum Radiolaria – make a test out of minerals
  • Phylum Foraminefera – make a test (shell) out of calcium carbonate. Supergroup Amoebozoa
  • Many types of amoebae
  • Move using pseudopodia
  • Entamoeba histolytica
  • Slime molds Zygotic life cycles
  • Most unicellular sexually reproducing protists o Tradeoffs of sexual reproduction ! Advantage: genetic recombination ! Disadvantage: require the support of structures for acquiring a mate and mating, takes energy
  • Haploid cells develop into gametes
  • (+) and (-) mating strains o Diploid dormant zygote develops with a tough cell wall o Zygote undergoes meiosis and produces 4 haploid cells
  • Thick-walled diploid zygotes o Survived like cysts
  • If conditions are good (sufficient nitrogen) reproduce asexually. Conditions change, stimulates cells to develop into gametes.
  • Disadvantage: only a few spores are made Sporic life cycle
  • Many multicellular green, red, and brown seaweeds
  • Also know as alternation of generations
  • 2 types of multicellular organisms o Haploid multicellular gametophyte – makes gametes o Diploid multicellular sporophyte – makes spores ! When mature, the diploid seaweed (sporophyte) produces spores through meiosis. ! Spores develop into male or female gametophyte, eggs secrete chemicals to attract flagellated sperm, fertilization produces diploid zygote, develops into mature sporophyte. o Many haploid spores can be produced
  • Gametophytes grow and produce gametangia at tips.
  • If water is present, flagellate sperm are released, swim to egg and fertilization occurs.
  • Zygote is protected and nourished by female gametophyte
  • Embryo develops in mature sporophyte o Bryophytes (only) not land plants # sporophyte retained on the female gametophyte

Lycophytes and Ferns (Seedless Vascular Plants)4/3/14 12:33 PM

Lycophytes, ferns and seed-producing plants are vascular plants or tracheophytes

  • Possess tracheids for water and mineral conduction and structural support
  • Vascular tissue occur in the major plant organs: stems, roots, and leaves Divered prior to the origin of seeds.
  • Seedless vascular plants.
  • Tracheids: are elongated cells in the xylem of vascular plants that serve in the transport of water and minerals
  • Xylem: transports water and some nutrients.
  • Phloem: transports organic nutrients. (sugars)
  • Lignin: waterproof material in cell walls of xylem Roots, stems, and leaves
  • Stems o Contain vascular tissue and produce leaves and sporangia o Contain phloem and xylem (contains tracheids and lignin)
  • Roots o Specialized for uptake of water and minerals from the environment o Rhizomes: a horizontal root, can send out other roots and shoots from different nodes.
  • Leaves o Photosynthetic function. Adaptations that foster stable internal water content
  • Waxy cuticle present on most surface of vascular plant sporophytes.
  • Cutin found in cuticle that helps prevent pathogen attack
  • Wax prevents desiccation
  • Stomata are pores that open and close to allow gas exchange while minimizing water loss. o Transpiration: water loss

Gymnosperms 4/3/14 12:33 PM

Plants

  • Wood: strengthens plant, allow them to grow tall and have many branches, leaves, seeds. o Wood contains tracheids for water transport ! Tracheid pits on side and end walls through which water moves. ! Valve-like torus (porous and non-porous central region) to prevent spread of air bubbles.
  • Pollen: allow seeds to disperse male gametophyte
  • Ovules: protect and nourish developing embryo
  • Seeds: allow plants to reproduce in diverse habitats (can be dispersed)
  • Vascular cambium-meristematic tissue that produces xylem and phloem
  • Resin ducts: help prevent attacks by pathogens and herbivores.
  • Homosporous: spores that are the same size
  • Heterosporous: spores of different sizes
  • Microsprorangium: produce many small microspores (ultimately pollen)
  • Megasporangium that produce megaspore (ultimately ovule)
  • Ovule: structure that gives rise to and contains female reproductive cells. Sporangia – pollen cones
  • Pollen cones (male strobili) consist of papery or membranous scales o Microsporangia in pairs toward bases of scales. Pollen – Conifers
  • Development
  • Immature male gametophyte o Meiosis produces microspores that then undergo mitosis to develop into pollen grains ! Pollen grain consists of four cells and a pair of air sacs " Air sacs add buoyancy in wind. Ovule cones
  • Reproduction o Pair of ovules at bases of ovule cone scales

o Ovule cones larger than pollen cones ! Have woody scales with inconspicuous bracts between. Ovules:

  • Integuments (2n) o Integument has a pore called micropyle where pollen enters
  • Megaspores are produced by meiosis in magasporangium- Mitosis of megaspore makes female gametophyte (megagametophyte)
  • Gametophyte has archegonia which will produce 2 eggs (only one zygote will mature into embryo)
  • Gametophyte accumulates large amounts of protein, lipids and carbohydrates to nourish developing embryo (seeds)
  • Sporophyte is dominant – produce ovule cone, pollen cone
  • Ovule cones – megaspore undergo mitosis to produce gametophyte and egg
  • Microspores undergo mitosis to ultimately form pollen that is dispersed into wind.
  • Pollen grain matures into gametophyte, pollen tube deivers the sperm to the egg, fertilization occurs.
  • Zygote develops into embryo in a seed Reduction of gametophyte occurs as from Bryophyte # Lycophytes# and Seed Plants. While sporophyte gets larger.

Endosperm – formed by double fertilization, typically triploid (3n) – (study structure.) – surrounds and nourishes the embryo. Cotyledons- embryonic first leaves of plant Fruit – structure that encloses and helps disperse the seed Mechanisms to avoid self-fertilization

  • Self incompatibility – mechanism that prevents pollen germination, pollen tube growth, fertilization, or embryo development
  • Dioecious – male and female plants (monoecious – male and female flower on the same plant)
  • Timing – produce pollen or ovule at different times
  • Ecology – specialist pollinators Vessel members
  • Advantage? o Tracheids – smaller, conduct at slower rates o Vessel elements – larger and conduct water much faster. Deciduous
  • Loss of ability to get water and decrease in water causes plan to limit photosynthesis and drop leaves. Secondary metabolism and angiosperm diversity
  • Production of chemicals that are not essential for basic metabolism.

4/3/14 12:33 PM