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 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 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

E.coliwell 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)

Structure

Plasma membranecompartmentalization

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

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

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

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

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