Cell Viruses - PowerPoint PPT Presentation

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Cell Viruses

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Title: Cell Viruses


1
Cells
  • M.Prasad Naidu
  • MSc Medical Biochemistry,
  • Ph.D.Research Scholar

2
What is the importance?
  • Division of labor
  • Increased Surface Area
  • Regulation

3
Prokaryotes
  • Simplest
  • No organelles
  • No nucleus
  • No membrane bound organelles
  • DNA uncomplexed by histones

4
Prokaryotes
5
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.

6
Bacteria
7
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.

8
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)

9
E. coli
10
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

11
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

12
Eukaryotes
  • More complex
  • More DNA
  • Has to be folded
  • histones (positively charged proteins)

13
Structure
14
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)

15
Nucleus
  • double membrane
  • contains DNA
  • genetic material
  • chromatin vs. chromosomes
  • nucleolus has RNA
  • histones proteins that are positively charged
    that wind up DNA

16
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

17
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

18
Mitochondria
  • ATP production
  • has its own DNA
  • uses nutrients to make energy
  • In plants, chloroplasts makes sugar from sunlight
  • Endosymbiotic theory

19
Lysosomes (Animal Cells)
  • Recycling centers can breakdown proteins
  • in plant cells these are vacuoles

20
Peroxisomes
  • Breakdown H2O2

21
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

22
Viruses
  • http//www.ucmp.berkeley.edu/alllife/virus.html

23
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

24
Famous Viruses
  • Smallpox, common cold, chickenpox, influenza,
    shingles, herpes, polio, rabies
  • Ebola
  • AIDS

25
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

26
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27
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