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
Methanogens
methane-producing
anaerobes = live in oxygen free environments
Halophiles
salt-loving
inhabit extreme saline environments
Thermophiles
heat-loving
inhabit areas such as hot sulfur springs, volcanoes, deep sea vents
grow best at temperatures above 70 degrees Celsius
Psydophiles
cold-loving
found in Arctic/Antarctic oceans and ice
grow best between -10 and -20 degrees Celsius
Survival of archaebacteria
very specialized enzymes to carry out chemical processes
anaerobic
lipid membranes withstand the extreme conditions
Shapes of eubacteria
coccus = round bacillus = oblong spirilla = spiral
Colony organization of eubacteria
staphylo = clumps strepto = chains diplo = pairs
Gram negative bacteria
they don’t hold the purple stain
more dangerous as they are more resistant to antibiotics
complex cell walls, smaller amounts of peptidoglycan, possess an outer lipid containing membrane which hides the antigens of the cells
Gram positive bacteria
they hold the purple stain
infections are more susceptible to common antibiotics
human body does not contain peptidoglycan and produces an enzyme which attacks the abundant peptidoglycan layer of the bacteria
Respiration of eubacteria
obligate aerobes = require oxygen
obligate anaerobes = require no oxygen
facultative anaerobes = can handle either
Grouping of protista
very diverse group
most are single celled
all are eukaryotes
Protozoa
animal like protists, but lack tissue and body cavities, unicellular heterotrophs variety of shapes and sizes complex life cycles live in aquatic environments grouped based on method of locomotion
Flagellates
move by means of whip like flagella
hard, protective covering over membrane
can be symbiotic, parasitic, or free-living
Sarcodines
amoebas
move and engulf prey by producing limb-like extensions (pseudopodia)
scavengers, parasites, or free-living
Sporozoans
parasites
form spores at some point in their life cycle
adapted to transferring offspring from one host to another
lack the means of independent movement
Ciliates
covered in tiny cilia
beat in coordinated rhythm to move organism
cilia sweep food into vacuole
often large and complex cells
Algae
plant-like protists, photosynthesize
contain chlorophyll
classified based on type of chloroplast and pigment
base of aquatic food webs (phytoplankton)
Green algae
live mainly in freshwater
unicellular or multicellular
Brown algae
live in colder saltwater
multicellular
Red algae
inhabit warmer saltwater
multicellular
Diatoms
most abundant unicellular algae in oceans
major food resource at bottom of food chain
major source of atmospheric oxygen
cells walls of silica, box-like construction
Dinoflagellates
major component at bottom of aquatic food chain
sometimes produce toxins that accumulate in filter feeders (shellfish)
Euglenoids
often capable of photosynthesis as well as eating
mainly freshwater species
Slime moulds
produce spores like fungi, glide and ingest food like protozoa, cellulose divides cell wall like plants
visible to naked eye
plasmodium contains many nuclei
moves to engulf food
