Life
• Individual survival– Take in, digest, eliminate nutrients– Recognize self from non-self– Recognize enemies– Repair damage
• Reproduction– Survival of species– Gene transfer
Bacteria
Archaea
Protozoa
Algae
Plants
FungiAnimals
InvertebratesVertebrates
US
UCA
Prokaryotes
Euk
aryo
tes
Sin
gle-
celle
d
Cell Functions• Maintenance
– Recovery of energy from nutrients– Storage of energy– Synthesis of correct proteins and other cell
components
• Perpetuation of self– DNA replication– Cell division
• Specialized functions– e.g. muscle, blood, nerve cells, immune system
The molecules of life
• Nucleic acids (DNA, RNA)
• Proteins
• Carbohydrates
• Lipids
• Lipoproteins, glycoproteins, vitamins….
DNA RNA Protein
DNA + DNA
Translation Protein synthesis
DNA ReplicationCell division
The ProteomeThe ProteomeProteomicsProteomics
GenomicsGenomicsThe GenomeThe Genome
Transcription
PROTEINS
• Chains of amino acids• Structural elements - cell walls, membranes• Catalysts - enzymes• Communication - within cells, between cells
• Cytokines• Signal transduction factors• Receptors• Vital for regulation of growth, cell division
Schematic metabolic cycle
Cellular components
Nucleic acids, Carbohydrates, Protein,
Fat
Metabolic intermediates
NADPHNADP+
Work
TransportAssemblyMovementHeat
ATP
ADP + Pi
Food
Carbohydrates, Fats, Glucose,
Proteins
Wastes
CO2, H2O, lactic acid
ATP
ADP + Pi
NAD+
NAD+
NADH
NADH
The Metabolome - Metabolomics
Viruses
• 0.02-0.3 micrometers diameter• Genetic material: ss or ds DNA, RNA • Protein coat• Some enzymes• Lipid envelope – enveloped/non enveloped
viruses• Nomenclature semi-systematic
– Hepatitis A Virus, HAV
• Need host cell for replication
The plasma membraneLipid bilayer
Polar
Non-polar
(Lipid)
Protein
Av. Width
7.5 nm
(75 Å)
Sugar
GlycolipidGlycoprotein
The Flu Virion
Neuraminidase
Hemagglutinin Lipid bilayer envelope
Matrix protein
• Envelope: lipid bilayer membrane + glycoproteins, typically acquired from host cell membranes
• Capsid (protein coat): multiple copies of 1 or more proteins in an array
Life-cycle of virus
• Particle, virion
• Infects host cell
• Genetic material uses host’s replication apparatus to produce new viral components (capsid, core proteins, genetic material)
• Components assemble into viral particles, exit host cell, sometimes lysing host cell
• Each type of virus has its own specific host
• Viruses that colonize bacteria are bacteriophage viruses (bacteriophages).
www.virustaxonomyonline.com
Viruses in the Environmment• Must be able to survive outside host cell• Non-enveloped viruses are more persistent than
enveloped viruses– Lipid envelope more easily damaged, protein
coat confers stability • Enteric viruses are almost all non-enveloped
– Hepatitis A, poliovirus, noroviruses, rotaviruses
– Transmitted by direct and indirect contact, fecally contaminated water, food, fomites and air.
• Respiratory viruses, mostly enveloped• adenoviruses, coronaviruses, rhinoviruses,
influenza viruses, • Transmitted by direct and indirect contact, air
(aerosols) and fomites (some also by water and food).
Unicellular organisms
• Bacteria - procaryotes
• Protozoa
• Algae - eucaryotes
• Fungi
Procaryotic Cell (left) and Eucaryotic Cell (right)
Procaryotes: Bacteria and Others
Unicellular organisms
Simple internal organization
Multiply by binary fission
Diameter ~0.5-1.0 micrometer
Envelope: cytoplasmic membrane, cell wall & capsule (polysaccharide)
Some have appendages:
flagella: for locomotion
pili: attachment to other cells for genetic transfer; virus receptor site
Standard Linnean nomenclature: Genus species
Diverse bacteriaGram positive Gram negative
More bacterial types
• Aerobes
• Anaerobes
• Facultative aerobes
• Rods (bacilli)
• Spherical (cocci)
• Comma-shaped (vibrios)
• Spiral (spirochetes)
Bacteria in the Environment
Some bacteria form spores:
– highly resistant to physical and chemical agents and
– very persistent in the environment
Pathogenic Bacteria
Pathogenic bacteria possess structures or chemical constituents that contribute to virulence properties – Outer cell membrane of Gram
negative bacteria: endotoxin (fever producer)
– Exotoxins– Pili: for attachment to cells and
tissues– Invasins: to invade cells
Unicellular Eucaryotes:
• More complex internal organization:
– organelles: discrete nucleus, mitochondria
• Wide range of sizes: 2 micrometers and larger
Protozoa
• Unicellular; non-photosynthetic; flexible cell membrane; no cell wall; some are parasites, have complex life-cycles
• Wide range of sizes and shapes; 2 micrometers to 2 mm• Disease-causing:
– Amoebae: Entamoeba histolytica– Flagellates: Giardia lamblia– Ciliates: Balantidum coli– Sporozoans: Plasmodium vivax– Coccidians: Cryptosporidium parvum– Microsporidia: Cyclosopora cayetanensis
Cryptosporidium parvum oocysts: ~5 m diameter
Acid fast stain of fecal preparation
Wet mount by differential interference contrast microscopy
Giardia lamblia cyst: ~10 x 8 micrometers
More Protozoans: Fungi
Fungi (yeasts and molds):•non-photosynthetic• immotile; •rigid cell wall
Molds:•grow as branched, interlacing chains or filaments (hyphae) called mycelia
•Yeasts:• do not form mycelia •grow as single cells that bud •sexual reproduction possible
Mitospores (conidia) of Penicillium, one of the asexual Ascomycota
Yeasts
Algae
• Photosynthetic• Rigid cell wall • Simple plants, protists,
protozoa, plancton, derived from cyanobacteria ?
• Wide range of sizes and shapes – 2 micrometers and larger
• Some algae are harmful– Algal booms
• Toxins– Anabaena, anatoxins
Nostoc
Helminths (Worms)
• Multicellular animals• Some are human and/or animal
parasites • Eggs pass via human and animal
excreta to water, food, soil.• Several major groups:
– Roundworms, Nematodes eg. Ascaris, Trichinella spiralis, hookworms
– Flatworms Platyhelminthes: Cestodes (tapeworms): pork, beef tapeworms, and Trematodes (flukes) eg Schistosomes
– Annelids (leeches)
Necator (hookworm)
eggs
adult
• Eggs hatch in soil• Infective stage: larvae• Penetrate skin, migrate to
blood, lungs, trachea • or are ingested• Adults mature in intestine• Attach to intestinal walls
– anemia– Necator americanus ,
Ancylostoma duodenale (hookworm)
Trematodes
• Schistosomes (blood flukes)
• Liver fluke
Cestodes
• Head (scolex) attaches to tissue– beef tapeworm,
Taenia saginata– pork tapeworm (T.
solium)
• Grows in intestine
http://www.marvistavet.com/html/body_tapeworm.html
Multicellular organisms
• Plants
• Animals– Invertebrates– Vertebrates
