Published on March 27, 2014
M.Prasad Naidu MSc Medical Biochemistry, Ph.D.Research Scholar
What is the importance? Division of labor Increased Surface Area Regulation
Prokaryotes Simplest No organelles No nucleus No membrane bound organelles DNA uncomplexed by histones
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.
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.
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)
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
E.coli Some strains frequently cause diarrhea in travelers, and it is the most common cause of urinary tract infections One strain, designated O157:H7, 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
Eukaryotes More complex More DNA Has to be folded histones (positively charged proteins)
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)
Nucleus double membrane contains DNA genetic material chromatin vs. chromosomes nucleolus has RNA histones: proteins that are positively charged that wind up DNA
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
Golgi Cellular post office Proteins synthesized in the ER are packaged with extras such as SO4 2-, 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
Mitochondria ATP production has its own DNA uses nutrients to make energy In plants, chloroplasts makes sugar from sunlight Endosymbiotic theory
Lysosomes (Animal Cells) Recycling centers can breakdown proteins in plant cells these are vacuoles
Peroxisomes Breakdown H2O2
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
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
Famous Viruses Smallpox, common cold, chickenpox, influenza, shingles, herpes, polio, rabies Ebola AIDS
Bacteriophages Viruses that infect bacteria Commonly used in molecular biology DNA isolated from tissue---> Packaged into bacteriophage DNA---> Bacteria culture grown and infected with bacteriophage---> DNA of interest is replicated and studied either on DNA level or protein level
Calcification Inhibitors in CKD and Dialysis Patients
A virus is a small parasite that cannot reproduce by itself. Once it infects a susceptible cell, however, a virus can direct the cell machinery to produce ...
Explore the structure of animal, plant, and bacteria cells along with their associated viruses with our three-dimensional graphics.
Virus Structure. Viruses are not plants, animals, or bacteria, but they are the quintessential parasites of the living kingdoms. Although they may seem ...
The evolutionary history of viruses represents a fascinating, albeit murky, topic for virologists and cell biologists. Because of the great diversity among ...
Are Viruses Alive? Although viruses challenge our concept of what "living" means, they are vital members of the web of life
Introduction to the Viruses. In 1898, Friedrich Loeffler and Paul Frosch found evidence that the cause of foot-and-mouth disease in livestock was an ...
Viruses exist for one purpose only: to reproduce. To do that, they have to take over the reproductive machinery of suitable host cells. Upon landing on an ...
Detection of EBV sequences in human cell lines of the B cell lineage by PCR. a, sample only; b, sample with internal control DNA
Capsid: a protective shell around the genome of a virus. Cell membrane: the outside layer of a cell that separates it from its environment. Envelope: ...
TEKS Covered •4A. Compare and contrast prokaryotic and eukaryotic cells. •4C. Compare the structures of viruses to cells, describe viral