Ch. 4 - Microbial Diversity: Acelluar Prokaryotes Flashcards
Virus constituents
- Genome
- Capsid - protein coat surrounding the genome which is composed of capsomeres
- Viral enveloppe
5 Properties that distinguish viruses from living cells
1) RNA OR DNA - living cells have both
2) Unable to replicate on their own (use machinery from cells they infect)
3) No mitosis, meiosis, or binary fission
4) Lack of genes/enzymes needed for energy production (use energy from host)
5) Dependant on host ribosomes, enzymes, and metabolites for protein and nucleic acid production
Caliciviruses
Cause actue gastroenteritis (vomitting/diarrhea)
Picoviruses
Small RNA virus Rinovirus (common cold) Polio virus Hep A Coxasckievirus
Reovirus
enterovirus (intestinal infection)
Rotavirus
Bad GI bugs, kills 800 000 people per year in developping countries. Developed countries have vaccines
Flavivirus
Arboviruses arthropod vectors
West nile
Yellow Fever
Zeka virus - doesnt normally have an affect, maybe mild fever, but pregnant women are seeing that there may be a link to microcephaly of the baby
Corona virus
Respiratory tract infections
- COVD-19
- SARS
Togaviruses
Zootonic viruses carried by mosquitoes that could lead to equine encephalitis
Rubella (german measles)
Rhabdoviruses
cause rabbies
paramyxoviruses
Cause measles and moxyvirus (mumps)
Orthomyxoviruses
cause the flu
Arenaviruses
cause hemorrhagic fever
Bunyaviruses
cause a number of febrile disease
Rodent host or arthropod vector with vertebrate host
Lentivirus
HIV
Oncovirus
cancer causing
HPV, ebsteen barr
Parvoviruses
Cause parvo in puppies. There are vaccines
Adenoviruses
Respiratory tract infections/pneumonia
Pink eye
Some tumours
Papillomavirus
Causes warts (genital warts/HPV)
Polymavirus
causes tumours (some cancerous)
Herpesvirus
Herpes simplex I (cold sores)
Herpes simplex II (genital herpes)
Herpes zoster (shingles/vericella)
Ebsteen-barr (3 cancers- 2 lymphomas)
Poxvirus
Variolla (small pox)
Vascina (cow pocks)
Hepadnaviruses
Hep B virus
Most viral genomes are ___ stranded _(RNA/DNA)__
double stranded DNA
or
Single stranded RNA
Bacteriophage
Viruses that infect bacteria
Virulent bacteriophage cause the ___ cycle
Lytic cycle - ends in cell destruction
Lytic cycle
Step 1) ATTACHMENT of phage to cell surface receptor
Step 2) PENETRATION of bacteriophage and insertion of phage DNA into cell
Step 3) BIOSYNTHESIS of new phage DNA and proteins
Step 4) ASSEMBLY of new phage particles
Step 5) LYSIS of cell and RELEASE of progeny phages
Steps in the multiplication of animal viruses
Step 1) ATTACHMENT of phage to cell surface receptor
Step 2) PENETRATION of bacteriophage and insertion of phage DNA into cell
Step 3) UNCOATING - because they have to penetrate the nucleus of eukaryotic cells
Step 4) BIOSYNTHESIS of new phage DNA and proteins
Step 5) ASSEMBLY of new phage particles
Step 6) LYSIS of cell and release of progeny phages or BUDDING off
Penetration of a host cell by a non-enveloped virus
Endocytosis:
1) bind to host cell membrane receptors
2) invagination of membrane
3) formation of endocytic vesicle
4) release or virion into cytoplasm
Penetration of a host cell by an enveloped virus
1) Bind to cell membrane receptor
2) fusion of viral envelope with host cell membrane
3) nucleocapsid enters the cell
Latent virus infection
Virus hides from host immune system by remaining dormant
ex- herpes
How do antivirals work?
Interfere with virus specific enzymes and virus production by disrupting critical phases in viral multiplication
OR
inhibiting synthesis of viral DNA/RNA proteins
What type of virus is HIV?
enveloped, single strnded, RNA
Retrovirus
What is a retrovirus
RNA virus that inserts a DNA copy of their genome into the host cel in order to replicate
What is the primary target of HIV
CD4+ cells (T helper)
HIV and reverse transcriptase
Converts viral RNA to DNA
Viroid
Short naked fragments of single stranded RNA that infect plants and interfere with their metabolism
Prions
They are the most resistant to disinfectants and can cause fatal neurological diseases in animals and humans. The mechanisms of how they cause disease is unknown
Diameters of virus and cocci bacterium
virus: 10-300nm
cocci bacterium 1um
3 categories of bacteria
Gram pos + cell wall
Gram - + cell wall
Mycoplasma
Diplococci bacteria
pairs
gonorrhea
streptococci bacteria
chains
strept throat
staphylococci bacteria
clusters
boils
Average size of bacillis
1x3um
Coccobacili
extremely short bacili, almost like ball
Bacteria fixation
Kill organism, preserve morphology, anchor to slide
Heat fixation - not standardized as heat may alter morphology
Methanol fixation - alcohol causes the water to dry up
Gram staining technique
1) fixation
2) crystal violet solution
3) rinse and flood with iodine. This will turn everything purple and increases the affinity of the cell wall for a stain by binding to the primary stain
4) Rinse excess iodine and decolourize with ethanol. This removes iodine from the cells that hold it as tightly, removing their stains
5) Rinse ethanol as soon as gram (-) loses its stain
6) Apply counter stain safarin
7) wash with water, blot, air dry
Gram variable bacteria
Neither consistently purple or pink after staining
Identified with acid fast stain
Acid Fast Stain
Red dye driven through bacterial cell wall suing heat to soften the waxes in cell wall.
Rinse- since mycobcteria are not decolourized by the acid-alcohol mix, they keep their stain
How to test bacterial motility
Semisolid agar method:
Fill test tube with agar, then dip a needle which has bacteria on it into the tube. Observe how/if they spread out
Hanging drop technique:
To study living bacteria
Allows more room to move and we can distinguish motility from Brownian motion
size of bacterial colonies is determined by ____
Generation time
Obligate aerobes
Need oxygen
Microarophillic anaerobes
Need some oxygen
facultative anaerobes
Can use oxygen or not - depends
Aerotolerant anaerobes
Can tolerate oxygen but don’t need it
Obligate anaerobes
need anaerobic environment
Capnophillic
need increased concentration of CO2
How do we test bacteria’s need for oxygen
Thioglycollate broth (THIO) -bacteria will migrate to the part of the tube where it will survive
Fastidious
organisms with especially demanding nutritional requirements
How are bacterial pathogens identified?
by the enzymes they secrete
Rickettsias
Gram (-)
obligate intracellular
leaky memrbanes
found in ticks, lice, flees..
Chlamydias
gram (-)
obligate intracelullar pathogen
energy parasites - they prefer to use energy molecules produced by the host cell
Name 2 obligate intracellular bacterial pathogens
Rickettsias , Chlamydias
Mycoplasms
smallest cellular microbe
lack cell wall therefore pleomorphic and resistant to drugs that attack cell walls
cause primary atypical pneumonia and GI infections
“fied egg colonies”
anogygenic photosynthesis
photosynthesis doesnt produce oxygen
purple bacteria
green bacteria
Oxygenic bacteria
photosynthesis produces oxygen
cyanobacteria
How do prokaryotes differ from bacteria?
they both posses cell walls, but prokaryotic cell walls do not contain peptidoglycan