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Advanced Biology Prokaryotes. Chapter 28. The first cells (28.1). Isotopic Data Carbon-12 is found in microfossils This is used for carbon dating of organisms and carbon fixation Pathways include: Calvin Cycle (photosynthesis) Krebs Cycle (cellular respiration) Hydrocarbons biomarkers.

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the first cells 28 1
The first cells (28.1)
  • Isotopic Data
    • Carbon-12 is found in microfossils
  • This is used for carbon dating of organisms and carbon fixation
    • Pathways include:
      • Calvin Cycle (photosynthesis)
      • Krebs Cycle (cellular respiration)
  • Hydrocarbons
    • biomarkers
  • The Earth formed approximately 4.5 billion years ago
  • The first fossil formations found on Earth are dated to 3.5 billion years ago
    • Microfossils
      • Fossil form of microscopic organisms
prokaryotic diversity 28 2
Prokaryotic Diversity (28.2)
  • Prokaryotes are the oldest form of life.
  • They have a simple structure and
  • They are also the most abundant form of life on Earth
    • Cyanobacteria (photosynthetic) changed Earth’s atmosphere to be able to produce oxygen
  • Abundant amounts of prokaryotes – ~10% identified
  • New techniques to identify w/o culturing
  • Two groups:
    • Archae and Eubacteria
prokaryotes can live anywhere
Prokaryotes can live anywhere
  • Found in deep sea caves, volcano rims and inside glacier formations
  • Some Archae are extremophiles – extreme environments such as hot springs, geysers, toxic gases and extreme cold (Anartica)
  • Extremes may indicate earth’s conditions 3.5 bya
prokaryote vs eukaryote
Prokaryote vs. eukaryote

Prokaryotes

Eukaryotes

Unicellular and multicellular

Cell size – normally ≥10ųm

Membrane bound nucleus

Mitosis – sexual

Genetic Diversity via Mutations

Membrane bound organelles

Flagella and cilia w/microtubules – whiplike

Photosynthesis release oxygen

  • Unicellular
  • Cell size – vary
    • ≤1ųm up to 750 ųm
  • Single circular chromosome
  • Plasmids
  • Binary Fission – asexual
  • Horizontal gene transfer
  • No internal compartments – ribosomes differ
  • Flagella – single fiber – spin
  • Oxygenic and anoxygenic
  • chemolithitrophic
slide6

Prokaryotes

  • Eukaryotes
archae vs eubacteria
Archae vs. eubacteria
  • Plasma membrane in both but differs in glycerol link to hydrocarbon chains
  • Cell Wall– Peptiglycan in Eubacteria but not in Archae
  • DNA Replication differs by place of origin and proteins
  • Gene Expression – Archae may have more than one RNA polymerase
classification
Classification
  • Classification of prokaryotes were gram staining and observations such as:
    • Can photosynthesize
    • Mobility
    • Unicellular or colonies
    • Spores or binary fission
    • Whether it is pathogenic
  • Now classified by evolutionary means using DNA analysis
prokaryote cell structure 28 3
Prokaryote cell structure (28.3)
  • Three basic forms:
    • Rod shaped (bacillus)
    • Sperical shaped (coccus)
    • Spiral shaped (spirillum or spirochetes)
cell structure
Cell structure
  • Cell wall determines cell shape
    • Lack cell wall, no particular cell shape
  • Flagella
  • Chains
  • Colonies
  • Branching filaments
cell wall
Cell Wall
  • Cell wall basically contains peptidoglycan with a polymer that forms a strand of crosslinked polysaccharides with peptide chains
  • Archae may have pseudomurein or pseudopeptidoglycan
gram staining
Gram staining

Gram + will stain purple

Thick Peptioglycanso traps crystal violet

Gram – will stain pink

Multiple layers does not trap crystal violet but will show the red dye

other stuctures
Other Stuctures
  • Capsule
    • Gel type outer layer
      • Allows for adherance and evasion from immune system
  • Flagella
    • Structure that allows movement connected at cell wall and spins – made of protein flagellin
slide16

Pili

    • Hairlike structure that allows movement (gram-), attachment and exchange of genetic information
slide17

Endospores

    • Dormant stage in prokaryotes
    • Thick wall formed when environmental stress
    • Stay dormant for days to centuries
      • Examples: Tetanusor anthrax
internal structures
Internal structures
  • Ribosomes
    • Smaller than Eukaryote ribosomes
    • Different proteins and RNA
    • Antibiotics will bind to these ribosomes blocking protein synthesis
  • Internal membranes
    • Respiratory membranes – photosynthesis
  • Nucleoid
    • Double stranded circular DNA (nucleoid region)
    • Plasmid – replicating circular DNA (small)
prokaryotic genetics 28 4
Prokaryotic genetics (28.4)
  • CONJUGATION
  • Prokaryotes reproduce asexually
  • Exchange DNA through
    • Conjugation - transfer plasmids (F+/F- )
    • Transduction
    • transformation
slide20

Transduction

    • DNA transfer from one bacterium to another via a virus
slide21

Transformation (Griffith) – Cell death causes lysis that releases fragments of DNA into the environment where another bacteria incorporates it into its genetic material

antibiotic resistance and mutations
Antibiotic resistance and Mutations
  • Due to its rapid reproduction a mutation in a bacterium can spread rapidly
    • Media growth (Nutrient Agar)
      • Auxotroph – need supplement
      • MRSA and VRSA
  • Plasmids can have resistant genes incorporated
    • E.coli found in digestive tract of humans vulnerable
prokaryotic metabolism 28 5
Prokaryotic Metabolism (28.5)
  • Photoautotrophs – sunlight to build from carbon dioxide
  • Chemolithoautotrophs – oxidize inorganic substances such as ammonia to nitrite
  • Photoheterotrophs – Sunlight for energy and other molecules for carbon
  • Chemohetertrophs – carbon and energy from other molecules
  • Intake of energy and carbon – 4 Ways:
    • Photoautotrophs
    • Chemolithoautotrophs
    • Photoheterotrophs
    • Chemoheterotrophs
human bacterial disease
Human Bacterial disease
  • See Table 28.1 on page 561.
  • Infective diseases by bacteria killed over 20% of US children before age 5 before the discovery of antibiotics by Pasteur and Koch
  • Bacteria can infect by various methods such as droplets in air, feces or pests
beneficial prokaryotes
Beneficial prokaryotes
  • Symbiotic relationships
    • Mutualism – nitrogen fixation or digestion
    • Commensalism - live outside of organism without harming
    • Parasitism - infection
  • Prokaryotes can cause harm but there are some that are beneficial
    • Bacterial decomposers along with fungi put C, N,P, S back into the soil
    • Fixation during nutrient cycling of carbon and nitrogen
slide26

Genetic Engineering

    • Human genes can be inserted into bacterium to produce human proteins such as insulin
    • Biofactories for enzymes, vitamins, antibiotics and industrial compounds
  • Bioremediation
    • Removing pollutants from water, air and/or soil
    • Bacterium used in wastewater treatment plants to breakdown raw sewage.
    • Future development in removing toxic waste
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