Bacteria and Viruses Biology Chapter 10 Kingdom Monera

Bacteria and Viruses Biology Chapter 10

Kingdom Monera l Divided now into ¡ Kingdom l l Archaebacteria ¡ Kingdom Eubacteria Outnumber all other living organisms combined Microscopic - 1000 times smaller than most human cells Exist EVERYWHERE! 100 -20, 000 in every cubic meter of air

Classification and Morphology l Microbiology – the study of microscopic organisms l Bacteria – all prokaryotic – lack nucleus ¡ Pathogenic – disease causing (minimal) ¡ Decomposer – breaking down of substances

Kingdom Archaebacteria l Live in extreme conditions. l Thermoacidophiles – highly acidic soils and hot springs (230 degree F) l Methanogens – live anaerobic conditions producing methane gas as waste l Halophiles – salt-loving; live in extremely salty conditions; metabolize salt to produce ATP

Kingdom Eubacteria l Largest of the two bacteria kingdoms l Scientists are continuing to fight over the organisms contained in this kingdom. l Most live in non-extreme environments.

Bacterial Shapes, Sizes, and Colonies l Shape and Size ¡ Coccus – spherical (~1 um diameter); a period could easily have 5, 000 coccus lined up across its diameter ¡ Bacillus – rod (~1 um in width and 2 -10 um in length) ¡ Spirillum – spiral or corkscrew shape (slightly longer than bacillus)

l Colonies – unicellular but living together ¡ Diplo – two cells joined together ¡ Strep – joined end-to-end in long chains Streptococcus l Streptococcus pneumoniae l ¡ Staph l – clustered together like grapes Staphylococcus

Bacteria Cell Walls and Capsules l Bacteria: ¡ Plasma membrane phospholipid bilayer which controls the flow of substances into and out of the cell ¡ Cell wall directly outside the plasma membrane; no cellulose; maintain shape of cell ¡ Capsule – outside cell wall; made of sticky carbohydrates; protects the cell from dry spells

Bacterial Cytoplasmic Structures l Nuclear area - DNA material appears as a circular chromosome l Plasmid – one or more smaller circular DNA chromosomes; carry only a few nonessential genes l Mesosomes – twisted invaginations of the plasma membrane supplying additional surface area for metabolic processes to occur

Bacteria Locomotive Structures l Flagella – long threadlike whip l Bacteria without flagella appear to vibrate back and forth as water molecules bump into them; can also appear to migrate with the flow of the liquid ¡ A. k. a – Brownian movement

Bacterial Reproduction and Growth l Bacteria grow to full size and divide every 30 minutes; over 1 billion bacteria is 15 hours; under 24 hours the cells would weigh over 2000 tons l Growth rate this fast cannot be sustained for long

Asexual Reproduction l Simple Binary Fission ¡ DNA replicates ¡ Plasma membrane has an invagination and forms two daughter cells l Can be completed in 9 minutes

Bacteria and Nutrition l Autotrophs ¡ ¡ l Photosynthetic – similar but uses different light wavelengths Chemosynthetic – involves converting inorganic compounds to other usable forms and capturing the energy Heterotrophic – vast majority; digesting organic substances ¡ ¡ Parasitic – feeding on a living host Saprophytic – feeding on dead organic matter

Conditions for Optimal Growth l Moisture – all require moisture to grow; capsule maintains internal moisture l Temperature – ideally normal is around 80 -100 degree F l p. H – most bacteria prefer a neutral condition l Nutrition – heterotrophs must obtain energy as well as materials necessary for bacterial biosynthesis

Optimal Growth Bacteria are very environmentally specific; what is beneficial to one may kill another l If conditions turn unfavorable then the bacteria create an endospore. l Endospore – one or more layers of hard material that form around the nuclear area to protect the DNA from the environment; when favorable conditions return the endospore will weaken and the bacteria will break out l

Bacteria and Oxygen l Obligate anaerobes – organisms that grow only in the absence of oxygen l Obligate aerobes – organisms that grow only in the presence of oxygen l Facultative anaerobes – organisms that can grow with or without oxygen

Bacteria and the Transfer of Genetic Material l Conjugation – the bacteria line up side by side and a tube is formed that connects the two; genetic material is passed in one direction l Transformation – living bacterial cells take up other bacteria’s free DNA from nonencapsulated bacteria l Transduction – transfer of genetic material by way of a virus called a bacteriophage

Terminology l l l l Microbiologist Bacteria Decomposer organism Thermoacidophile Methanogen Halophile Coccus Bacillus Spirillum Capsule Nuclear area Plasmid Mesosome l l l l Chemosynthetic Parasitic Saprophytic Endospore Obligate anaerobe Obligate aerobe Facultative anaerobe Conjugation Transformation Transduction Heterotroph Autotroph Brownian movement

Viruses l Virology – the study of viruses l Viruses contain two basic parts: ¡ Core – either DNA or RNA (never both) ¡ Capsid – a protein covering ¡ Envelope – only some have it; made of lipids l Virion – entire virus unit l Obligate intracellular parasites – must have host for life

Classifying Viruses l Two large groups: ¡ DNA containing or RNA containing; then whether the DNA or RNA is single or double stranded l Also classified by: ¡ Shape ¡ Presence or absence of an envelope ¡ Method of infecting and replicating within the host cell

Viroids and Prions l Viroid – smaller than a virus; a short single strand of circular RNA; no capsid or envelope l Prion – smaller than a viroid; abnormal form of a protein; does not contain any nucleic acids

Vaccinations l Typically a small dose of the actual virus in a weakened condition. l Allows the body to build up an immunity for the disease.

Viral Replication l Virulence – the ability of a pathogen to affect cells l Lytic cycle – the activity cycle of a virulent virus

Lytic Cycle Lytic cycle has five stages: 1. 2. 3. 4. 5. Attachment – virus attaches to host cell Entry – virus core is injected into the host cell Replication and transcription – using the cell’s enzymes and organelles, the virus begins to produce multiple copies of the viral nucleic acid Assembly – the virus proteins form capsids around the replicated viral DNA or RNA forming new virions Release – lysis occurs and the virions are released into the organism to attach to new host cells and repeat the lytic cycle.

Lytic vs. Lysogenic Cycles The lytic cycle begins to destroy the host cell upon entry. l The lysogenic cycle allows the virus to remain dormant within the host cell and is duplicated when the cell undergoes mitosis thereby creating a whole population of cells that contain the virus. Once the virus is stimulated it enters the lytic cycle and destroys the host cell; after stimulus it returns to dormancy. l

Viral Diseases l VERY specific regarding the host cell. l Diseases are controlled through vaccinations.

Disease Terminology l l l Pathogen – an agent that invades the body and causes a disease Incubation period – the time between being infected and the first appearance of a symptom Communicable disease – a disease that can be spread from one person to another by either direct or indirect means Vector – insects or other arthropods that carry pathogens from one host organisms to another Carrier – a healthy-appearing individual can spread the disease to others but have no symptoms themselves

l Structural defenses – prevent pathogens from entering the body l Nonspecific defenses – internal responses to the presence of a pathogen l Specific defenses – chemotherapy directed toward a specific pathogen

l Disorders – afflictions not caused by a pathogen ¡ Inherited ¡ Injuries ¡ Organic l Tumor – a group of non-functioning cells that grow a different structure • Benign – tumor is slow growing and localized • Malignant – tumor grows rapidly and chaotic • Metastasize – separate from parent tumor and travel