BIOEE1780 Diversity 1

  1. LUCA and the universal characteristics of Life
    • LUCA is the last universal common ancestor.
    • LUCA had RNA and DNA.This is the basis for biological inheritance. LUCA either had RNA or DNA (debated)
    • LUCA replicated that RNA or DNA through semiconservative replication.
    • LUCA had triplets of nucleotides called codons that encoded for one of the 20 amino acids. These amino acids build proteins to carry out essential functions through transcription and translation.
    • LUCA had ATP (adenine triphosphate) which is the cellular energy currency in all cells.
    • LUCA was unicellular and had a membrane around the outside of the cell.
    • It also did not have organelles. Mitochondria and chloroplasts only appear later on in eukaryotes through endosymbiosis.
  2. Why are the universal characteristic of life significant?
    • These striking similarities prove a single origin of life.
    • Bacteria
    • Singular circular chromosome.
    • No membrane enclosed nucleus.
    • Few membrane enclosed organelles. (no mitochondria or chloroplast)
    • Peptidoglycan cell wall. Groups of bacteria can be taxonomically identified by the amount of this. (gram staining)
    • Ester linked membrane lipids.
    • Only reproduce asexually through binary fission where the DNA is replicated and the parent cell is divided into two daughter cells. This is convenient because individuals can rapidly divide to make two individuals without a hassle. (This characteristic allows them to be successful pathogens)
    • Undergoes horizontal or lateral gene transfer.
  3. Archaea
    • Singular circular chromosome.
    • No membrane enclosed nucleus.
    • No membrane enclosed organelles.
    • No peptidoglycan cell wall.
    • Ether linked membrane lipids. These allow them to live in extreme conditions because they are more stable than other ester linkages.
    • Only reproduce asexually through binary fission where the DNA is replicated and the parent cell is divided into two daughter cells. This is convenient because individuals can rapidly divide to make two individuals without a hassle.
    • Undergoes horizontal or lateral gene transfer.
    • Have DNA with histones and introns. (like eukaryotes)
  4. Eukarya
    • Linear chromosomes.
    • Membrane enclosed nucleus.
    • Many membrane enclosed organelles
    • Single cell eukaryotes are called protists.
    • No peptidoglycan cell wall.
    • Ether linked membrane lipids
    • Closer to Archaea than Bacteria. However, mitochondria and chloroplast originated from endosymbiosis with a bacterium. Thus, some genes are closer to archaea and some to bacteria.
    • Have DNA with histones and introns.
  5. “Prokaryote”
    • Includes archaea and bacteria. Thus, a paraphyletic group.
    • Means before nucleus.
    • Most abundant organisms on our planet.
    • Capable of living in inhospitable places that would kill most other life forms, incredibly effective parasites or mutualists etc.
  6. Spirochetes
    • Spirilla
    • Spiral shaped bacteria with axial filaments, motile
    • Lyme disease, Syphilis
  7. Chlamydias
    • Sister taxa of spirochetes.
    • Small obligate parasites that can cause STDs, eye infections or pneumonia.
    • They infect animals as well (koalas)
    • Unique reproductive cycle.
  8. Proteobacteria
    • Gram negative bacteria (disease and nitrogen fixation)
    • Generally heterotrophic but can be autotrophic.
    • Exhibit the highest metabolic diversity of any organismal group - more so than even animals.
    • Can be photoautotrophs, chemoautotrophs, photoheterotrophs, chemoheterotrophs.
    • Gave rise to mitochondria in eukaryotes.
  9. Cyanobacteria
    Photoautotrophic prokaryotes that later on give rise to chloroplasts in eukaryotes.
  10. Lyme disease
    • Caused by spirochetes
    • Spirilla
    • Spiral
  11. Syphilis
    • Spirilla
    • Spiral
  12. E. coli
    • Proteobacteria
    • Lives in GI tract but can cause deadly food poisoning.
  13. Salmonella
    • Proteobacteria
    • Food poisoning, animal feces
  14. Vibrio cholerae
    • Proteobacteria
    • Cholera, contaminated water
  15. Yersinia pestis
    • Proteobacteria
    • Cause of bubonic plague.
  16. Bacillus anthrax
    • Rod shaped
    • Bacilli
    • Source of anthrax
  17. Staphylococcus
    • Cocci
    • Round
    • Live on your skin but can cause deadly staph infections.
  18. Stromatolite
    Rocks that are formed from biofilms of cyanobacteria trapping layers of sediment. Some of the oldest evidence of life on our planet are stromatolites that were found in Greenland and dated 3.78 Bya.
  19. Domains
    • Primary divisions of life.
    • Bacteria
    • Archaea
    • Eukaryotes
  20. Photoautotroph
    • They harvest CO2 from the atmosphere and use sunlight to produce glucose.
    • Cyanobacteria are photoautotrophs.
  21. binary fission
    Arhcaea and Bacteria undergo this from of asexual reproduction. DNA is replicated and the parent cell is divided into two identical daughter cells. This is convenient for rapid reproduction.
  22. Peptidoglycan
    • Only bacteria have this in their cell walls. They can be taxonomically identified through the amount of this in their cell wall. Gram positive means more peptidoglycan and gram negative means less peptidoglycan.
    • Excellent target for fighting bacteria pathogens, since eukaryotes don’t have it.
  23. Biofilm
    Prokaryotes are always unicellular, but they are able to form large colonial groups called biofilms. An example is dental plaque.
  24. Halophiles
    Archaeans that survive in highly saline environments.
  25. horizontal (lateral) gene transfer
    • One bacterium (archaea) has a plasmid to be transferred.
    • A connection is formed and the plasmid is copied.
    • Both bacteria now have the plasmid.
    • The recipient may even integrate the plasmid to the chromosome.
    • This is how antibiotic resistance is spread across bacterial strains.
  26. ether linkages (as synapomorphy for archaea)
    • More stable form of linkage in membrane lipids.
    • This is useful to ensure survival in extreme conditions.
  27. Gram-negative
    Gram negative means less peptidoglycan in bacterial cell wall. (Gram staining)
  28. Gram-positive
    Gram positive means more peptidoglycan in bacterial cell wall. (Gram staining)
  29. Cocci
    • Bacteria with a round, spherical shape.
    • Staphylococcus.
  30. Spirilla
    • Spiral shaped bacteria with filaments that run along the long axis.
    • They use these filaments to move and can be highly mobile.
    • Spirochete (Lyme disease), Syphilis,
  31. Bacilli
    • Rod shaped bacteria.
    • Bacillus anthracis.
  32. Three major types of bacteria based on shape:
    • Cocci: round
    • Spirilla: spiral
    • Bacilli: Rod shaped bacteria
  33. All life forms share:
    • Nucleic acids, DNA or RNA, as hereditary materials
    • The same triplet genetic code to specific amino acids.
    • The same biochemical pathways, enzymes, ATP
    • Molecular mechanisms to replicate either DNA or RNA
    • Plasma membrane
    • Unicellular
  34. When did LUCA occur?
    3.7 billion ya.
  35. What is the age of the Earth?”
    4.6 billion ya.
  36. How do we know when LUCA occurred?
    • (3.9 billion) There are chemical signals in rocks that can tell you whether or not life was present in the rocks. High 12C/13C ratio in graphite particles compared to what is expected in non-biological deposits indicates life. However, a bunch of abiotic processes may produce the same signal. Take this with a grain of salt.
    • (3.7 billion) A more reliable evidence is the presence of stromatolites.
  37. How are archaea and eukarya united?
    Both have DNA with histones and introns (non-coding regions)
  38. What about viruses?
    • They don’t have a nucleus.
    • They lack mitochondria.
    • They are parasites
    • They lack ATP and the molecular machinery for replication.
  39. Giant viruses?
    • Large size: up to 1.5 micrometer
    • Complex genome with double stranded DNA with 100s of genes.
  40. Why are viruses placed outside of the tree of life?
    We are uncertain where they fit.
  41. Model Organisms?
    • Bacteria: E. Coli
    • Angiosperms: Arabidopsis thaliana
    • Fungi: Saccharomyces cerevisiae
    • Arthropoda: Drosophila melanogaster
    • Nematoda: C. elegans (roundworm, transparent)
    • Chordata: Mus musculus
  42. Where are Archaeans found?
    • extremophiles
    • Soil
    • Ocean plankton
    • microbiomes
  43. What are methanogens?
    • Produce methane as a part of GI tract.
    • We share many of the methanogen archaea in our GI tract with great apes. Humans have reduced gut microbiome diversity, especially in urban environments!
  44. this group has the highest metabolic diversity of any group
    proteobacteria
  45. sister group to bacillus anthracis
    staphylococcus
  46. paraphyletic group with bacteria and archaea
    prokaryotes
Author
pelinpoyraz
ID
351052
Card Set
BIOEE1780 Diversity 1
Description
prokaryotes
Updated