Diversity of Living Things - Chapter 2 Flashcards
Viruses
consist of hereditary material (DNA or RNA), and a capsid (protein coat with protruding glycoproteins)
some viruses contain protein knobs that allow interaction with cell membrane receptors on their target cell
not living organisms = not composed of cells, not capable of reproduction in absence of a suitable host cell
Lytic cycle of bacteriophage
recognition = virus recognizes target cell, and capsid combines with cell receptor insertion = genetic component is injected into host cell replication = viral DNA causes bacteria to synthesize new phage components assembly = new phages self-assemble lysis = bateria burst (lyses), releases bacteriophages
Lysogenic cycle of bacteriophage
recognition and insertion occurs
viral DNA is incorporated into host chromosome and remains dormant
bacterial reproduction occurs, and each daughter cell contains viral DNA
phage DNA is activated and new phages are produced
Transduction
incorporation of host cell DNA into the viral DNA
sometimes leads to new viral properties
Vaccines
compromised versions of the virus trigger immune response (development of antibodies) that will be remembered for any future viral infection
Usefulness of viruses
gene therapy uses viruses to deliver a new copy of a gene to a malfunctioning cell
target drug delivery uses viruses to deliver a drug to a diseased cell
Roles of bacteria
recycling production of products poison-eating food digestion vitamin synthesis nitrogen fixation source of antibiotics
Bacteria reproduction
binary fission = DNA duplicates inside cell, then separates into two separate daughter cells
conjugation = pilus connects cells forming cytoplasmic bridge, “male” delivers genetic material (usually plasmid) to “female” cell
Plasmids
small circles of double-stranded DNA found in some bacteria
often contains genes for resistance
often used as vectors in recombinant DNA technology
Transformation
the process in which a bacterial cell takes in and uses pieces of DNA from its environment
if genes come from another species, it is called lateral gene transfer
Bacteria survival
microorganisms sense and adapt to changes in their environment
some bacteria may become motile or produce enzymes to exploit alternative resources
Endospores
develop during time of stress
can survive extreme environmental conditions
they are not readily killed by may antimicrobial agents
Harmfull effects of bacteria
compromised cell function, destruction of healthy cells, production of toxins
spread by = airborne, dust, direct contact, fecal contamination, animal bites, wounds
Prevention against bacteria
body’s defense mechanisms sterilization/disinfection extermination of diseased animals immunization administration of antibiotics
Antibiotics
naturally produced by bacteria or fungi
penicillin, streptomycin
important to take the entire dosage even if symptoms improve
Bacteria resistance
variation within species allows for survival of the fittest
those that survive antibiotic treatment pass immunities to offspring
