Download Topic 2 week 2 Learning objectives

Topic 2 week 2 Learning objectives
Learning objective questions – Why study microbiology?
What is microbiology?
Is the study of microbes.
When do we think microbes first appeared?
Where are microbes found?
Microbes live in boiling mud pits, in the pacific ocean and everywhere.
What are the major categories of microbes?
Acellular microbes including viruses and prions and cellular including prokaryotes and eukaryotes.
What are pathogens?
Are disease causing micro-organisms.
What are non-pathogens?
Microbes that do not cause disease.
What are indigenous microflora?
Are those microbes that normally reside on the body and do not usually cause disease.
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What are opportunistic pathogens?
Are those pathogens if given the right circumstances for example an immune deficiency can cause
disease.
What are saprophytes
Are organisms which obtain nutrients from dead organic matter.
What is an infectious diseae?
Results from the colonization of a particular microbe.
What is microbial intoxication?
Is the ingestion of a toxin produced by microbes.
Learning objective questions – What are acellular microbes?
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What microbes are acellular?
They are non-living microbes and include viruses, prions and viroids.
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What is the range of virus sizes?
Most viruses range from between 10-300nm in diameter but can be up to 1um in length.
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What organisms can be infected by virsuses?
Viruses can infect all types of organisms including humans, animals, fungi, plants and bacteria.
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What properties distinguish viruses from living cells?
Viruses need a host cell to replicate whereas living cells divide by mitosis, meiosis or binary fission.
Living cells can produce their own energy and proteins whereas viruses need a host cells to do this.
Most viruses have either DNA or RNA whereas living cells possess both of these.
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What is the general structure of viruses?
The general structure of a virus includes a genome of DNA or RNA, a protein coat called a capsid.
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What are capsids?
Protein coat made of protein.
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What are capsomeres?
Proteins which make up the protein coat of a virus
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How are viruses classified?
Classified based on type of virus they cause, whether they contain RNA or DNA, type of host cell they
invade, whether they have an envelope or not and its target cell.
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What are bacteriophages?
Viruses that infect bacteria.
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What are animal viruses?
Refers to viruses that infect animals.
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What are the steps in animal virus multiplication?
Step 1: Attachment: virus attaches to the receptor on host cell
Step 2: Penetration: virus enters the host cell
Step 3: Uncoating: DNA or RNA is released from the capsid into the host cell.
Step 4: Biosynthesis: host cell is used to produce all the parts needed to make new copies of
that virus.
Step 5: Assembly: new virus particles are made
Step 6: Release: the newly formed virus particles escaped from the host cell.
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What determines whether viruses attach to cells?
This depends on whether the host cell has a receptor which is highly specific to the virus.
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What is uncoating?
Whereby the DNA or RNA is released from the capsid into the host cell.
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What occurs during biosynthesis?
During biosynthesis the host cell produces all of the required parts to form new copies of
that particular virus.
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What are latent viruses?
Virus latency is the ability of a pathogenic virus to lie dormant (latent) within a cell. A latent
viral infection is a type of persistent viral infection which is distinguished from a chronic viral
infection
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What are viroids?
Are infectious particles that consist of short pieces of naked RNA which interfere with plant
functioning.
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What are prions?
Are infectious proteins which have the capacity to cause neurological diseases in humans
such as spongyform encethopathy.
Learning objective questions – What are cellular microbes?
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What are the two broad classes of cellular microbes?
These include prokaryotes such as bacteria and archae and eukaryotes which include fungi,
yeast and protozoa.
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Which microbes are procaryotes?
Bacteria and archea.
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What is the structure of a procaryote cell?
Lacks membrane bound organelles; the chromosome of prokaryotes consists of a single,
long, circular DNA molecule which is highly coiled around itself. It also contains plasmids
which are pieces of circular DNA.
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What is the cell membrane?
It encloses all of the contents of the cell and is composed of phospholipids.
What is the structure of the bacterial chromosome?
The chromosome is a single, long circular DNA molecule which is highly coiled around itself.
What are plasmids?
Are small pieces of circular DNA which are not part of the main chromosome.
What is the cytoplasm?
Is the semi-liquid substance which contains water, salt and nutrients.
What is the cell wall? What is its function?
Is a rigid structure on the outside of the plasma membrane which provides structural
support, strength and protection for the cell.
What is the bacterial cell wall made of?
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It is made of peptidoglycan which is only found in bacteria.
What is the structure of the cell wall of gram-positive bacteria?
They have a thick layer of peptidoglycan on the outside surface of the cell wall.
What is the structure of the cell wall of gram-negative bacteria?
They have a thin layer of peptidoglycan that is sandwiched between many other complex
layers.
What is the glycocalyx?
A slimy, gelatinous substance that is secreted on the outside of the cell wall. It facilities
movement of bacteria.
What is a slime-layer?
Is a type of glycocalyx that allows movement.
What is a capsule?
A highly organised layer that is firmly attached to the outside of the cell wall and they help
prevent bacteria from being ingested by cells of the immune system.
What are flagella?
Threadlike appendages that function to move bacteria around.
What are pili (or fimbriae)?
Hair like structures located on the outside surface of bacteria often found on gram negative
bacteria. Pili allow for attachment of bacteria to surfaces and also allows transfer of genetic
material from one bacteria to another.
What are endospores?
Thick walled structures that contain a copy o the chromosome and some of the cytoplasm
and are produced during times of stress.
How do procaryotic cells reproduce?
Prokaryotic cells reproduce by binary fission.
How do procaryotic cells differ from eucaryotic cells?
Prokaryotic cells lack internal membranes and have their DNA free floating within the
cytoplasm, have a cell wall whereas eukaryotic cells possess internal membranes and have
their DNA within a nucleus, do not have a cell wall and also have much larger and denser
ribosome compared to prokaryotic.
Learning objective questions – How do we classify microbes?
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What is the binomial system of nomenclature?
is a formal system of naming species of living things by giving each a name composed of two
parts, both of which use Latin grammatical forms, although they can be based on words
from other languages.
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What two domains are composed of prokaryote organisms?
Bacteria and archaea.
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How can bacteria be classified based on cell morphology?
There are three basic shape of bacteria:
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Cocci-round or spherical bacteria
Bacilli- rod-shaped or rectangle
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Spirilla- curved and spiral shaped
How is the Gram-stain used to characterise bacteria?
Gram stain is used as the colour that is observed depends on the chemical composition of
the cell wall.
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How can mycobacteria be stained?
To stain mycobacteria a different stain called an acid-fast stain is used which results in the
bacteria appearing red in colour.
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How can you characterise bacteria based on motility?
If bacteria are motile they have flagella but if non-motile they lack a flagella.
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How can you characterise bacteria based on colony morphology?
Includes shape, colour, overall size and shape, elevation and the appearance of the edge of
the colony.
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How can you characterise bacteria based on atmospheric oxygen reguirements?
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What are obligate aerobes?
Bacteria that have an absolute requirement for an atmosphere with around 20%
oxygen.
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What are microaerophiles?
Bacteria that also have an absolute requirement for an oxygen-containing
atmosphere of about 5%.
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What are obligate anaerobes?
Organisms that do not require oxygen to sustain life or reproduce.
What are aerotolerant anaerobes?
Bacteria that can grow in atmospheres with oxygen but grow better in environments
that do not have oxygen.
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What are facultative anaerobes?
Bacteria that are capable of surviving in atmospheres that either contain or do not
contain oxygen. They tolerate oxygen levels from around 0- -20%.
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What are some other characteristics that can be used to characterise bacteria?
Nutritional requirements, metabolic processes, pathogenecity and genetic
composition.
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What makes Rickettsias , Chlamydias, and mycoplasmas unique?
Rickettsias and chlamydias are both Gram-negative bacteria but they are both
obligate intracellular pathogens and cannot survive outside of a host cell.
Mycoplasmas are the smallest of the cellular microbes and they do not possess a cell
wall this means they can take on many different shapes.
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What are the eucaryotic microbes?
Prions, protozoa and viroids.
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What are algae?
Algae are photosynthetic eukaryotic organisms.
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What are protozoa? Where are they mostly found?
Are eukaryotic organisms which are mostly unicellular and they are found in soil and
water and are more like animal cells than plant cells.
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What are the two stages of a typical protozoan life cycle?
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What is the trophozoite stage?
The motile, feeding, dividing stage.
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What is the cyst stage?
Non-motile, dormant, survival stage.
Learning objective questions – How do we classify microbes?
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What are the categories of protozoa?
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What are amoeba?
They move by extending portions of their cell membrane and cytoplasm in structures
called pseudopodia.
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What are ciliates?
Move using a large number of hair-like cilia on the outside surface of the cell.
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What are flagelates?
Move using a whip-like flagella.
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What are sporozoa?
They are non-motile and do not contain pseudopia, cilia or flagella.
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What fungi are microbes?
They are a diverse group of eukaryotes that include yeasts, moulds and mushrooms.
Where are fungi found?
They are found almost everywhere and some live on organic matter in water and soil
and other on animals and plants.
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What are yeasts and where are they found?
Yeasts are single celled eukaryotic organisms that are found in soil and water and on
the skin of vegetables and fruit.
Learning objective questions – Microbial ecology?
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What is microbial ecology?
Is the study of interrelationships between organisms and their environments.
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What is symbiosis?
A term used to describe the living together of dissimilar organisms.
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What is neutralism?
A symbiotic relationship where neither of the symbionts are affected by the association.
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What is commensalism?
Is a symboiant relationship where one of the symbionts derives benefit from the association
but the relationship is neither beneficial or harmful to the other.
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What is a host?
A living organism that harbours another living organism.
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What is mutualism?
Is a symbiotic relationship where both symbionts derive benefit from the
association.
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What is parasitism?
A symbiotic relationship where only one symbionts (the parasite) derives benefit.
The other symbiont (the host) is harmed.
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What are indigenous microflora?
Are all the microbes that normally reside on or in your body. A foetus has no
indigenous micro flora and these develop through exposure after birth.
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Where are most of the indigenous microflora found?
On the skin, in the ears, the mouth, the upper respiratory tract, gastrointestinal tract
and genitourinary tract.
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What parts of the body are usually sterile?
Your blood, lymphatic fluid, cerebrospinal fluid, most internal tissues and organs.
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What are some benefits of microbes for humans?
They produce certain nutrients such as vitamin K and B12 in the gastrointestinal
tract.
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What is microbial antagonism?
Your indigenous microflora act to prevent the invasion and colonisation by
other microbes.
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What are opportunistic pathogens?
Pathogens that if given the right circumstance can cause disease.
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What are biofilms?
Learning objective questions – Epidemiology
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What is epidemiology?
Is the study of the factors that determine the frequency, the distribution and causes of
human disease.
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What is a communicable disease?
Is any infectious disease that can be transmitted from one person to another.
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What is a contagious disease?
Is an infectious disease that is easily transmitted from one person to another.
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What is a zoonotic disease?
Is an infectious disease that humans acquire from animal sources.
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What does the term incidence refer to?
Refers to the number of new cases of a particular disease within a certain population within
a specific period of time.
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What does the term mortality rate refer to?
Is the ratio of the number of people who died from a specific disease over a specified time
period in a specific region.
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What is a sporadic disease?
Is a disease that only occurs occasionally within a population of a specific geographical
location.
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What are endemic diseases?
Is a disease that is always present at some level within a population of a specific
geographical area.
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What are epidemic diseases?
A disease that is occurring in greater than usual numbers within a specific geographical region and
they usually only last a short period of time.
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What are pandemic diseases?
Is a disease that is occurring in epidemic proportions in many countries at the same time.
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What are the components of a “chain of infection”
Source of infection, reservoir, portal of exit, mode of transmission, portal of entry and
susceptible host.
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What are reservoirs of infection?
Are the sources of microbes that cause infectious disease.
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What is a carrier?
A person who is infected with a particular pathogen but where the pathogen is not causing
disease in that person.
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What are passive carriers?
A person who carries a disease causing pathogen without having ever had the disease.
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What is an incubatory carrier?
A person who is capable of transmitting a pathogen during the incubation period of that
particular infectious disease.
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What is a convalescent carrier?
A person who can transmit a particular pathogen while recovering from an infectious
disease.
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What is an active carrier?
A person who has completely recovered from a particular disease but still harbor the
disease causing pathogen indefinitely.
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What are some important animals reservoirs of infectious diseases?
These include birds, dogs, mosquito vectors and cattle.
Learning objective questions – Epidemiology
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What are some important non-living reservoirs of infectious diseases?
Dust, soil, water, dirt, food and fomites.
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What are fomites?
They are inanimate objects capable of transmitting pathogens.
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What are the 5 principle modes of transmission?
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How are communicable diseases most commonly transmitted?
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Contact (direct or indirect)
Droplets
Airborne
Vehicular
Vector
Direct via skin- skin contact
Dirct via mucous membrane to mucous membrane contact
Indirect via contact with airborne droplets
Indirect via contact with food or water contaminated with fecal matter
Indirect via contact with arthropod vectors
Indirect vi contact with contaminated fomites
Indirect via contact with contaminated blood or blood products or by parental injection
What are health-care associated infections (HAIs)?
They are infections acquired within hospitals or healthcare facilities.
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What are community acquired infections?
Infections that are acquired outside a healthcare facility.
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What are iatrogenic infections?
Is an infection that results from medical or surgical treatment.
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What are the principle modes of transmission of HAIs?
Contact transmission, droplet transmission and airborne transmission.
Learning objective questions – Controlling the growth of microbes
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What factors affect the growth of microbes?
pH, temp, availability of nutrients, moisture ad gaseous requirement.
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What does generation time refer to?
The time it takes for one cell to divide into two cells.
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What are artificial (or synthetic) media?
Media that do not occur naturally but rather they are produced in labs.
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What is a chemically defined media?
Is one where all the ingredients and components of the media are know
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What is a complex media?
Is one where the exact components of the media are not known this is because they contain
ingredients from animals, fish or plants.
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What is a selective media?
Is a media that discourages the growth of some organisms while not affecting the growth of
other organisms.
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What is a differential media?
Media that allows you to differentiate between different types of organisms that are
growing on the media.
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How do you grow obligate intracellular organisms?
They need a host to survive so can be grown using embryonated chicken eggs, lab animals
or other cells in culture.
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What is sterilization?
Is the destruction/ elimination of ALL microbes
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What is disinfection?
Is the elimination of most or all pathogens from non living objects.
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What is a disinfectant?
Are chemicals that are used to kill microbes on inanimate objects.
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What is an antiseptic?
Are chemicals that are used to disinfect skin and other living tissues.
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What is sanitization?
Is the reduction of microbial populations to levels that are considered safe by public health
standards.
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What are microbicidal agents? What types are there?
Are chemicals that such as disinfectants and antiseptics that kill microbes and examples
include fungicidal agents, bactericidal agents.
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What are microbistatic agents?
Are substances that inhibit the growth of microbes but do not necessarily kill them.
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What is sepsis?
Is the presence of pathogens in the blood or tissues.
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What is asepsis?
Is the absence of pathogens.
Learning objective questions – Controlling the growth of microbes
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What is aseptic technique?
A collection of techniques that are used to eliminate and exclude pathogens
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What is sterile technique?
Techniques used to exclude ALL microbes from a particular area.
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What are some physical method to inhibit microbe growth?
Heat, heat and pressure together such as auotclaves, radiation and filtration.
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What two factors do heat sterilization depend on?
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What are the characteristics of an ideal chemical antimicrobial agent?
They should be fast acting, be non-toxic to humans, be able to kill a wide variety of microbes and be
soluble in water.