3. Microbiology Flashcards
Microbes
Living organisms and non-living entities
So small, can only be viewed with the aid of various microscopes.
3 main roles of microbes
- Affect human health
- Essential for life on this planet - produce oxygen
- Antibiotic production
Other roles of microbes
Genetic engineering
Food production
Decomposition of dead organisms
2 main categories of microbes
- Cellular - prokaryotes, eukaryotes
2. Acellular - require other living cells to reproduce, contain no cells
Pathogens
Disease causing microorganisms (aka infectious agents)
Non - pathogens
Microbes that do not cause disease
Opportunistic pathogen
Pathogens that take advantage of an opportunity not normally available. e.g a host with a weakened immune system.
Thrush
Infectious disease
Disease caused by a pathogenic microorganism
Acellular microbe
Microbes that need to invade other cells to replicate or perform physiological functions
Viroids
Infectious particles that consist of short pieces of RNA that interfere with the function of plant cells
Prions
Infectious particles that consist of small proteins that can cause neurological conditions.
Bacteriophages
Viruses that infect bacteria
Obligate intracellular parasites
Capable of growing and reproducing inside the cells of a host
Why is it difficult to design anti-virus drugs?
Because it is hard to kill the virus without killing the host cell
Cellular microbes
Can be divided into prokaryotes and eukaryotes
2 main categories of cellular microbes
- Bacteria
2. Archaea
Plasma membrane function (prokaryotic microbes)
Encloses all contents of the cell
Plasmid (prokaryotic microbes)
gene carrying, circular DNA structure
Cytoplasm (prokaryotic microbes)
Contains water, salts, enzymes, nutrients, proteins, carbohydrates, lipids,
gel like substance
Cell wall (prokaryotic microbes)
Provides strength and protein for the cell wall
Ribosomes (prokaryotic microbes)
Responsible for protein production
Structure of Gram-positive bacteria
Thick layer of peptidoglycan on the wall outside of the surface of the cell wall
Structure of gram-negative bacteria
Thinner layer of peptidoglycan
sandwiched between layers of other complex molecules
Endospores
Thick walled structure
contains a copy of the chromosome and some of the cytoplasm
Advantage of endospores
Allow bacteria to survive in adverse conditions
Binary fission
When prokaryotic cells produce
Produces two new cells
Rickettsias
Gram-negative bacteria
Obligate intracellular pathogen
e.g Rocky Mountain spotted fever
Chlamydias
gram-negative bacteria
Obligate intracellular pathogen
e.g chlamydia
Mycoplasmas
Smallest of the cellular microbes
Do not possess a cell wall
Ecology
Examines relations of organisms between one another and the environment
Symbiosis
The living together of dissimilar organisms. e.g individuals of two different species living close together
Symbionts
Organisms involved in the symbiotic relationship
3 types of symbiotic relationship
- Commensalism
- Mutualism
- Parasitism
Commensalism (anything is fine)
One species derives benefit from the association, but the relationship is neither beneficial of harmful to the other
Mutualism (win - win)
Both symbionts derive benefit from the association
Parasitism (win -lose)
Only one of the symbionts (the parasite) derives benefit, the other symbiont (host) is harmed
Indigenous microflora
The microbes that live on or in the human body
Functions of indigenous microflora
Synthesis of vitamins b and k
Stimulate the immune system
Inhibit invasion by growth of pathogenic microbes
Biofilm
Complex communities of different microbes attached to a surface with a slime layer. e.g dental plaque
Epidemiology
The study of occurrence, spread, and control of disease
Epidemiologists
Study the factors that determine the frequency, distribution and causes of human disease
Communicable disease
Any infectious disease that can be transmitted from one person to another
Contagious disease
Any infectious disease that is easily transmitted from one person to another. e.g corona virus
Zoonotic disease
An infectious disease that humans catch from animals. e.g mosquitos - malaria
Measures of epidemiology
Incidence
Morbidity rate
Mortality rate
Sporadic disease
A disease that occurs only occasionally within a population of a specific geographical area
Endemic disease (local)
A disease that is always present at some level within a population of a specific geographical area
Epidemic (national)
A disease that is occurring greater than usual numbers within a specific geographical are
Pandemic (global)
A disease that is occurring in epidemic proportions in many countries at the same time. e.g corona virus
Principle modes of infectious disease transmission
Contact (direct or indirect) Droplet Airborne Vehicular Vector
Healthcare associated infections (HAI’s)
Infections that are acquired within hospitals or other healthcare facilities
Community acquired infections
Infections that are acquired outside a healthcare facility. e.g influenza
Factors that affect growth of microbes
Availability of nutrients
Moisture
Temperature
pH
Generation time
The time it takes for one cell to divide into two cells
Selective media
A media that distinguishes the growth of some organisms while not affecting the growth of other organisms.
Differential media
A media that allows you to differentiate between different types of organisms that are all growing on the media
Sterilisation
The destruction/elimination of all microbes
Disinfection
The elimination of most or all pathogens (except endospores) from non-living objects
Sanitisation
The reduction of microbial populations to levels that are considered safe by public health standards.
Disinfectants
Chemicals that are used to kill microbes on inanimate objects
Antiseptics
Chemicals that are used to disinfect skin and other living tissue
Microbicidal agents
Chemicals such as disinfectants and antiseptics, that kill microbes
Microbiostatic agents
Substances that inhibit the growth of microbes but do not necessarily kill them
Bacteriostatic
Slows the growth. e.g fridge
Bactericidal
Inhibits growth. e.g freezer
Sepsis
The presence of pathogens in the blood or tissues
Asepsis
the absence of pathogens
