Exam 1: Lecture 2 Flashcards
How do we develop immunity?
- virus enters the body
- virus enters cell
- virus will do what it does and replicate inside cell
- virus product released, APC will bind it
- APC will displace virus to activate helper T-cell
- T helper cells causes B cell to make antibodies, which will block virus from infecting cells and mark for destruction
- Cytotoxic T cells id and destroy virus-infected cells
- Long-lived T/B cells chill in body for months or years and provide immunity
How long have microbes been around?
1st organism 3.5 B yrs ago (prokaryotes)
2.5 B yrs ago Eukaryotes came along (1 B yr after ^)
1 B yrs ago got multi-celled organisms (1.5 B yr after ^)
500M yrs ago development of brain (0.5 B yr after ^)
475M yrs ago life moves to land
250M yrs ago we get mammals
150K-200k yrs ago humans showed up
If you imagine Earth began as a single day…..
Microbes appeared at 5 am
Dinosaurs appeared at 10pm
….. humans appeared seconds before midnight
Archaea
- When 1st discovered 1977, thought to be bacteria
- exists in extreme (original thought) and less extreme places
- Humans have low lvls of archaea, don’t know importance
- Statins and Metronidazole eliminate them
3 kingdoms
- Bacteria
- Archaea
- Eukaryotes
What is considered Prokaryota?
Bacteria
Archaea
What is considered Eukaryota?
Plantae
Fungi
Animalia
Protista
Plantae info from tree of life
- contain chlorophyll, necessary for photosynthesis
- cell walls made of cellulose, fixed in one place
Fungi Info from tree of life
- usually motionless, absorb nutrients
- inc mushrooms, molds, and yeasts
Animalia info from tree of life
- most complex organisms on earth
- divided into vertebrates and invertebrates
Protista info from tree of life
- single celled organisms that have nucleus
- usually live in water
- made up of protozoa, unicellular algae, slime molds
- ex include algae, paramecium, amoeba
Bacteria inform tree of life
- single celled organisms that don’t have nucleus
- more forms of bacteria than any other organism on earth
Archaea info from tree of life
- bacteria with internal membranes
6 groups of pathogens
- Bacteria
- Viruses
- Fungi
- Protozoa
- Parasites
- Prion proteins
Order of Dec - Inc complexity
Viruses - Bacteria - Fungi - Parasites
Goal of viruses
Viruses exist to make more viruses
Virus structure
- core of RNA or DNA enclosed in capsid, or protein coat
- Glycoprotein envelope surrounds the capsid
- surface proteins inserted into envelope, help attach to host cell
How virus invades cell?
- Virus enters a cell
- Substances in the cell begin to strip the virus’s outer coat of protein
- The nucleic acid in the center of the virus is released
- Nucleic acid gets into the cells chemical manufacturing system
- Cell “ignores” its own chemical needs and switches to making new viruses
- Cell is sometimes destroyed in process. Many new viruses are released to infect other cells
Viral Shedding
expulsion and release of virus progeny following successful reproduction during a host-cell infection
Bacteriophage viruses
- Virus has head or “capsid” in which DNA is packed under very high pressure
- when attach to bacterium, uses pressure to inject DNA
- DNA integrates into DNA of host
- bacteriophage choose between two different life styles…dormant/latent or burst/lyse (kills bacterium)
Bacteria info
- single celled microbes
- no nucleus or membrane bound organelles
- Genetic info is contained in single loop of DNA
- Some bacteria have extra circle of genetic material
(plasmid) . it contents genes that give bacterium advantage over other bacteria. ie antibiotic resistance
Typical fungi spore size
1-40 micrometers in length
Which kingdom of microbes do fungi belong to?
usually saprophytes (consume dead organisms)
Example of human fungal pathogen
Candida albicans
it will raise pH of surrounding environment, causing alkalization
causes a white tongue
Prion Theory
- Nerve cell makes normal PrP proteins
- Prion version of PrP invades, forcing normal PrP to refold into a prion form
- Unlike normal PrP, prions aren’t naturally destroyed by the cell. They accumulate, eventually killing it.
- Prions move to other cells, cycle begins again
Mad cow and other wasting disease of the brain are caused by….
prions, not bacteria or viruses
Creutzfeldt-Jakob disease causes
- caused by abnormal proteins called prions that are not killed by standard methods for sterilizing surgical equipment
- prions build up in cells, brain slowly shrinks and tissue fills with holes until it looks like a sponge
Creutzfeldt-Jakob disease consequences
Those affected lose ability to think and move properly and suffer from memory loss
always fatal, about 1yr from onset
4 Developments that have taken us from a 2-generation society to a four
- vaccination
- Hygienic Medical Practice
- Chlorination
- Antibiotics
Vaccine info
only have 34 vaccines for 400 known pathogens
Examples of Hygienic Medical Practice
Handwashing
Moving from antiseptic to aseptic
Ruber gloves, masks, gloves
What is water Chlorination
process of adding chlorine or hypochlorite to water
used to kill certain bacteria and other microbes in tap water
used to prevent spread of waterborne diseases such as cholera, dysentary, typhoid
Antibiotics & Alexander Fleming
Discovered penicillin in 1928
shared Nobel Prize w/ Howard Florey and Ernst Boris Chain in 1945
Koch’s postulates purpose
criteria designed to establish a causative relationship between a microbe and a disease
Koch’s postulates
- Microorganism must be found in abundance in all organisms suffering from the disease, but should not be found in healthy organisms
- Microorganism must be isolated form a diseased organism and grown in pure culture
- Cultured microorganism should cause disease when introduced into a healthy organism
- Microorganism must be preisolated form the inoculated, diseased experimental host and identified as being identical to the original specific causative agent
Becoming a healthy human is…
impossible without microbes
important for homeostasis
Endemic
constant presence (regularly found among particular people or in a certain area)
Epidemic
Localized outbreak
Pandemic
Widespread regional or global epidemic
Infectivity
frequency with which an infection is transmitted when there is contact between the agent and a susceptible individual
ex, how many of those HIV positive will develop AIDS
Disease Index
Number of persons who develop the disease divided by the total number infected
Virulence
number of fatal or severe cases per total number of cases
Incidence
number of new cases of a disease within a specified period
described as a rate in which the number of cases is on top, and number of people in population under surveillance is on bottom
ex. observe how many cases in 100ppl over 3 weeks
Prevalence
described as a rate to indicate total number of cases existing in a population at risk at a point in time.
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