Cell Viruses

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Cells

• M.Prasad Naidu
• MSc Medical Biochemistry,
• Ph.D.Research Scholar

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What is the importance?

• Division of labor
• Increased Surface Area
• Regulation

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Prokaryotes

• Simplest
• No organelles
• No nucleus
• No membrane bound organelles
• DNA uncomplexed by histones

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Prokaryotes
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Prokaryotes

• Prokaryotes can live in the coldest, hottest,
  most acidic and most highly pressurized
  environments.
• They can live in places such as beneath the earth
  in bare rock, under glaciers, floating around in
  clouds and miles down on the sea floor at
  temperatures greater than 100 C.

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Bacteria
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Bacteria

• Bacteria live mostly on the surfaces of objects
  where they grow as colonies.
• Bacteria are important in making soil, feeding
  cows, controlling insects, making medicines,
  making bioplastics, making plants grow, degrading
  pollutants such as oil and plastics as well as in
  causing disease.

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Bacteria

• Most bacterial species are un-named and
  unidentified
• Tens of thousands of species have been isolated
• There are more than 15,000 known species of
  bacteria living in the sea
• Most famous is E.coli (Escherichia coli)

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E. coli
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E.coli

• well studied
• cell envelope
• plasma membrane constitutes 2
• pili (for adherence to cells)
• flagella (for propulsion through aqueous
  environment)
• chemistry similar to ours

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E.coli

• Some strains frequently cause diarrhea in
  travelers, and it is the most common cause of
  urinary tract infections
• One strain, designated O157H7, is particularly
  virulent and has been responsible for several
  dangerous outbreaks in people eating contaminated
  food (usually undercooked hamburger).
• Several important drugs (insulin, for example)
  are now manufactured in E. coli

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Eukaryotes

• More complex
• More DNA
• Has to be folded
• histones (positively charged proteins)

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Structure
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Plasma membrane

• compartmentalization
• huge number of proteins
• transporters (nutrient carriers)
• receptors (signal transduction)
• lipids and protein
• semi-permeable (polar and charged ions cannot
  cross freely)

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Nucleus

• double membrane
• contains DNA
• genetic material
• chromatin vs. chromosomes
• nucleolus has RNA
• histones proteins that are positively charged
  that wind up DNA

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Endoplasmic Reticulum

• Rough ER
• ribosomes
• protein synthesis occurs here for those proteins
  that will be routed out of cell
• Smooth ER
• lipid synthesis
• metabolism of drugs and toxic substances

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Golgi

• Cellular post office
• Proteins synthesized in the ER are packaged with
  extras such as
• SO42-, carbohydrates, lipid moieties
• Then, the proteins are directed to either the
  cell membrane to outside the cell or within the
  cell.
• In other words, the proteins are flagged for
  their next destination

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Mitochondria

• ATP production
• has its own DNA
• uses nutrients to make energy
• In plants, chloroplasts makes sugar from sunlight
• Endosymbiotic theory

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Lysosomes (Animal Cells)

• Recycling centers can breakdown proteins
• in plant cells these are vacuoles

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Peroxisomes

• Breakdown H2O2

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Cytoskeleton

• internal organization, assists the plasma
  membrane in retaining cell shape, and allows the
  cell to move
• microtubules
• rods from tubulin
• arrangement
• motion
• Actin protein filament for cell rigidity
• Myosin moves along actin using ATP

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Viruses

• http//www.ucmp.berkeley.edu/alllife/virus.html

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Viruses

• Contains nucleic acid surrounded by protective
  shell or capsid
• Uses host cells enzymes and ribosomes for
  replication
• Lysogenic phase viruses may remain dormant
  inside host cells for long periods. There is no
  obvious change in their host cells
• Can enter the lytic phase new viruses are
  produced, assemble, and burst out of the host
  cell.
• The cell is killed and other cells are infected

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Famous Viruses

• Smallpox, common cold, chickenpox, influenza,
  shingles, herpes, polio, rabies
• Ebola
• AIDS

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Bacteriophages

• Viruses that infect bacteria
• Commonly used in molecular biology
• DNA isolated from tissue---gt Packaged into
  bacteriophage DNA---gt Bacteria culture grown and
  infected with bacteriophage---gt DNA of interest
  is replicated and studied either on DNA level or
  protein level

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Thank you