Lecture 4

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Lecture 4
2013-10-03 10:26:32
Prokaryotic Cell Structure Function

Prokaryotice cell structure and function plasma membrane
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  1. Bacteria do not have sterols (cholestrol) in their plasma membrane. What do they have and why?
    Haponoids to stabilize membrane.
  2. What is the function of the plasma membrane?
    • Serve as a selective permeable
    • Barrier for materials entering and exiting
    • Retains cytoplasm
    • Transport system for nutrient uptake and waste excretion, and protein secretion
  3. What is the plasma membrane of Archaea?
    • Have no phospholipid bilayer but a single layer
    • Ether-linked molecules (glycerol)
  4. Percentage of water in cytoplasm, refered to as the internal matrix of the cell contained within the plasma membrane..
  5. What are the major structures of the cytoplasm?
    • Highly organized protein location has
    • Dna, ribosomes and inclusions
  6. as of 2001, what does the cytoplasm known to have?
    the Cytoskeleton.
  7. what kind of filaments does it have?
    similar matrix of Microfilaments, microtubules and intermediate filaments.
  8. Does the matrix contain proteins not found in eukaryotes and serve as scaffolding for cytoplasmic ocmponents and help bacteria maintatin its shape and aid in division?
  9. What are the Bacteria and Archaea Actin homologues of the cytoskeleton?
    • MreB
    • ParM
    • MamK
  10. What is the tubulin homologue of Bacteria and Archaea?
  11. What is the intermediate filament homologue?
    Crescentin (Caulobacter cresentus)
  12. What is the composition of Ribosomes?
    Protein and ribonucleic acid and is the site for protein synthesis located in the cytoplasmic matrix and attached to the plasma membrane.
  13. What is required of the ribosomes for synthesis of proteins to remain in the cell?
    to be in the Matrix.
  14. What happens if the Ribosomes are attached to the plasma membrane?
    The proteins synthesized get transported outside the cell.
  15. what is the size of procaryotic ribosome?
    70S (Svedberg units) smaller than eukaryotic ribosomes (80S). 30 +50 (Bacterial Ribosome?
  16. What is the difference between Bacterial and eukaryotic rRna?
    16s archaeal rna is more similar to 18s rRna not 16s rRna.
  17. What does the procaryotes chromosomes look like in the nucleoid?
    • Double stranded and circular.
    • some have linear chromosomes
  18. Which bacteria have linear chromosomes?
    • Borrelia.
    • Branched is rare.
  19. Supercoiling
    • Dna wound into a smaller unit
    • dna is twisted in the opposite direction from the right-handed double helix.
  20. What helps supercoil the chromosome?
    Condensin and Rna
  21. What do proaryotic chromosomes not have?
  22. What are the two main types of supercoiling?
    Positive supercoiling and negative supercoiling
  23. Positive supercoiling
    Is when additional turns are introduced and left-handed supercoiling; overwinding.
  24. Negative supercoiling
    Results when addtional turns are removed and right-handed supercoiling; underwinding.
  25. Supercoiling in bacteria has to tenzyme types.
    Topoisomerase 1 and 2
  26. Type 1/ Toopoisomerase 1:
    • Cuts one strand of Dna; reanneals the strand and relaxes the helix
    • Also used to reduce some of the tensional strain produced by the unwinding of Dna
  27. Type 2/ Dna gyrase:
    • cats both strands of Dna; reanneals the strands
    • allows unbroken strands of dna to pass through
    • used to introduce supercoils, knots; important in catenation
  28. Supercoiling is accomplished by the use of archaela...
    histone proteins
  29. Archaelal histones + Dna=
    archaeal nucleosome
  30. similar to eukaryotice nucleosome h3 and h4 is
    archaeal nucleosome
  31. What are the five types of supercoiling nucleosomes?
    H1, h2a, h2b, h3, and h4 form eight molecules, 2 from each except h1.
  32. Where does replication begin in bacteria/eubacterial genetics?
    the Ori site or initiation of replication (origin of replication)
  33. What does the Ori site use?
    a multi-enzyme replication complex, which binds to the the origin of replication and initiates unwinding and separation of the two dna strands.
  34. Theta replication
    replication method of bacterial chromosomes
  35. What method is used for replication of a bacterial plasmid?
    the rolling circle method.