Prokaryotes—Quick Review! Prokaryotes are single celled organisms that do NOT have a membrane bound nucleus. Prokaryotes are the most numerous organisms on Earth and live almost everywhere—every square centimeter! Most prokaryotes are BACTERIA
Identifying Prokaryotes Prokaryotes are identified by 3 characteristics: 3 shapes: rod, spherical, spiral Shapes Thick walls, thin walls Cell Walls No movement, flagella, lash/snake/spiral forward, glide on secreted material Movement
Gram Stains and Cell Walls Bacteria can be classified into 2 categories based on the structure of their cell walls using GRAM STAIN. GRAM NEGATIVE BACTERIA take up the red of the gram stain process, turning reddish pink under a microscope GRAM POSITIVE BACTERIA take up the purple dye and look purple under a microscope.
Bacteria—Structure and Function Cell wall, cell membrane, cytoplasm DNA, floating Capsule—outer covering made of polysaccharides Pili—short, hair-like proteins on the surface of the bacteria, helps bacteria attach to surfaces and cells
Importance of Bacteria! Bacteria are VITAL to the living world Some are producers Some are decomposers Others have human uses (cleaning up oil, medicines, human health )
Bacteria and Health (note: many bacteria are good for us!) PATHOLOGY is the scientific study of disease EXOTOXINS are toxic substances that bacteria secrete into their environment (tetanus) ENDOTOXINS are toxic substances that are part of the outer membrane of bacteria and are not released until the cell dies (E.Coli) ANTIBIOTICS are chemicals that inhibit the growth or kill bacteria ANTIBIOTIC RESISTANCE is the evolution of populations of bacteria to resist (and not die) antibiotics.
Antibiotic Resistance Activity What can you conclude about genetic variation and bacterial survival?
Controlling Bacteria Sterilization with Heat Destroys bacteria Exposes bacteria to great heat Disinfectants Chemical solutions designed to kill bacteria Overuse of antibacterial compounds can lead to bacteria evolving to resist them Food Storage and Processing Store food in fridge (low temperatures need more time for bacteria to grow) Boiling, frying, steaming will sterilize bacteria
Viruses! A VIRUS is a nonliving particle made up or nucleic acid and a protein coat (a CAPSID) and cause disease. Viruses are VERY small Viruses are NOT living because: They lack cytoplasm They lack organelles No metabolism or homeostasis Can only reproduce while in a host cell
VIRAL REPLICATION Outside the host cell, a virus is a lifeless particle with no control over its movements It is spread by air, in water, in food, or body fluids A virus recognizes a host cell and then attaches to it and the infection begins Once in a host cell the viruses DNA can make mRNA or the viruses RNA serves as mRNA and they begin to replicate more viruses
Viral Infection Once a virus is inside a host cell 2 different processes may occur— Lytic Infection or Lysogenic Infection
Lytic Infection Virus enters the cell, makes copies of itself, causes the cell to burst. When the cell bursts all of the copies are released and can infect other cells
Lysogenic Infection Virus enters host cell, integrates its DNA into the DNA of the host cell, and the viral DNA replicates along with the host cell DNA. The Viral DNA can remain in the cell for generations Eventually the viral DNA leaves and becomes a lytic infenct
Viral Diseases Since viruses are lifeless they must be spread by other agents…humans, animals, insects, etc. Common Viral Diseases: Chicken pox, shingles, viral hepatitis, HIV, SARS, Avian Flu, West Nile, Influenza Virus Song!
Virus Treatment Vaccinations and Vector Control A VACCINE is a solution that contains a harmless version of the virus (inactive or weakened).VACCINE VECTOR CONTROL is a the control of animal vectors such as mosquito and rabies control Drugs/Medications do not work well on viruses because it is hard to find something that can block the virus but not harm the host cell.
Comparing Bacteria and Viruses Comparing Bacteria and Viruses #2 Watch the clips Create a t-chart to list characteristics of both bacteria and viruses After the video clips, add to the t-chart Write an 8 sentence or longer paragraph to compare and contrast bacteria and viruses.