W1 Characteristics of Microorganisms Flashcards
4 types of microorganisms and general description
protozoa- move by flagella or amoeboid motion have nucleus and plasma membrane and usually feed on bacteria. an example is Giardia which attaches to the intestine wall causing diarrhea due to lack of absorption
fungi- nonphotosynthetic, nucleus and cell wall, two catagories which are yeast-unicellular oval and bud an example of a yeast is candida and the other is mold which is a multicellular clump or growth and it produces spores an example is ringworm or athletes foot
bacteria-unicellular cell wall no nucleus and they are ubiquitous ex is strep throat
viruses- non living require host to reproduce simple structure ex aids
size
microorganisms smaller than 0.1 ml or 100 micro meters there is size variation between microorganisms
us micrometers to meassure 1/1000 milimeters
bacteria shapes
coccus-round
bacillis- rectangular
spirilla- coils or curvy
gram reaction of bacteria
gram stain divides bacteria into two groups and makes them more visible
dark blue= gram positive
red or pink= gram negative
the gram reaction helps to identify the effectiveness of antibiotics and the effectiveness of disinfectants
there are 6 groups- gram positive coccus gram negative coccus, gram positive bacillis, gram negative bacillis, gram positive spirilla, gram negative spirilla
bacteria endospores
a few GRAM POSITIVE RODS can produce these
bacteria not producing endospores or that cant are in vegetative state or vegetative cells which means they are growing
sporulation occurs when nutrients are deplete4d and the DNA copies and the cytoplasm are inclosed in a protien coat
a spore is considered viable when it is able to germinate in its ideal conditions.
the cycle is vegetative cell then endospore formation then free endospore then germination and the cycle repeats.
spores are ubiquitous but need specific conditions to germinate.
ex: gangrene and tetanus if a deep injury occurs a spore could be imbedded in the the tissue and due to the lack of oxygen which is the tetanus spores ideal environment the spore could undergo germination
anthrax does can survive in the presence of oxygen but needs to grow in the lungs
endospores and disinfection or sterilization
most are resistant to heat- boiling point not adequate.
some need up to 121 degrees c to be destroyed
a lot are resistant to disinfectants and you must use high levels or multiple ones to cleanse said area
and all are usually resistant to the cold, ultraviolet light, acids, alkalis, and detergents.
Growth of bacteria
grow through binary fission which is elongation of cell then DNA replication then seperation and cell wall generation then division.
generation time
time that binary fission takes to occur. Or population doubles. It varies depending on the strain of bacteria, the nutrients present, and the condition the bacteria is in.
- For rapidly growing bacteria, in ideal conditions the usual generation time is between 15-30 minutes.
generation is related to rate at which bacteria cause disease for example gengren has a generation time of about 8 minutes and this means that someone could lose a limb within a day.
The generation time also determines the rate of grouth on a culture
a colony is a mass of bacteria and it represents all the descendants of a single bacteria cell. and they usually take within 18 to 24 hours to form
growth curve of bacteria
the reproduction of bacteria is curtailed to the decrease in nutrients and space and the increase in the accumulation of toxic waste.
If a bacteria cell is exposed to a NEW medium there are 4 specific phases of growth which is the:
-lag phase where it adapts to the new environment in a patient this is the incubation period and symptoms are not showing
-log phase which is the max growth of the bacteria and it is dividing at a constant rate this is when the onset of symptoms in a patient it is the acute phase and it sometimes results in the death of the patient
stationary phase- the supply of nutrients is exhausted and the rate at which new bacteria are born is equal to the rate at which the other bacteria die so growth stops - this is the phase at which the patients condition does not get better or worse.
death- the bacteria die and this can be a short or a long time and this is where spores are usually formed. for a patient this is when the symptoms subside.
*convellescent period is the time required for a full recovery of the patient
viruses
- can only multiple within host
- only contain one type of nucleic acid dna or rna
they have a protien coat and an enveloped virus would have a layer of lipids and spikes. these ones with the envelope are easier to disinfect except for hep b
multiplication of viruses
to multiply the virus attaches to receptor cites on host cell. the host cell makes a vesicle of the membrane called endocytosis and the host tries to destroy the virus by destroying the protein coat,this releases the nucleic material of the virus into the host cell once it reaches the nucleus it causes the nucleus to make more dna or rna and in the cytoplasm the nucleus of the cell in turn calls for the construction of the other viral components. When the cell becomes overly saturated with viruses or viral parts it will break open allowing the virus to infect other cells.
ex: influenza a this creates a pandemic because the rna mutates at a higher rate and does not allow for immunizations to be effective
or influenza c or b this one is more local
effect of virus on host
kills host cels due to lysis when full or the diversion of the cells natural metabollic pathway. Or the lymphocytes destroy the cell.
some vriuses alter or mutate the hosts cells dna creating a tumor cell this happens to the liver with hep b and it causes liver cancer. these viruses are called oncogenic
virus control
immunization
alcyclovir- genital herpes
zidovudine- aids
