Microbology Flashcards
Micro organisms
We have more of these than any other cell types in our body
Survive in extremes
Micro organisms are universal
Survive in extremes
Some organisms able to make spores
Involved in producing medicines, and vitamins
Destroy rubbish
Make cheese, wine
Colonise our surfaces
Regulate immunity
Bacteria
Prokaryotes
Tend to be larger, and classed according to shape
Cocci round
Rod oval
Spiral curved
Have two names escherichia coli
Bacterial cell wall
Gram positive bacteria have a thicker cell wall, and take up gram stain > purple
Gram negative organisms have a thinner wall, and not to take up gram stain > red
Viruses
Classed as DNA, RND or retroviruses
Genetic material protected by envelope
Enter host cell, and take over functioning, release viral proteins, finally destroy cell.
Cause AIDS, common cold, rabies, chicken pox, small pox, herpes and come cancers.
Types of outbreak
Sporadic
Endemic
Epidemic
Pandemic
Healthy protection agency CDC
Virulence and pathogenicity
Virulence is the power of an organism to overcome host defences and to produce disease
ID 50
LD 50
Pathogenicity is the ability to make one Ill
Portal of entry
Mucous membrane of respiratory or GI tract
Skin
Parental route
Adherence
Most organisms need to adhere to host tissue, adh sin or Luganda on surface of cell, often on pili or flagella
most are glycoproteins or lipoproteins
bind to specific receptors on host, most are sugar
Enzymes
Some organisms can increase virulence by releasing extra cellular enzymes
Coagulates
Kinases
Hyaluronidase breaks down hyaluronic acid
Collagenase
IgA protease
Antigenic variation
Alter surface antigens, often by altering gene expression
Bacterial damage to host cell 1
Using host nutrients
Iron needed by most bacteria, but is tightly bound to transport proteins so bacteria sidrephore
Cell unable to use iron, that may be even be toxic
Bacterial damage to host cell 2
Direct damage
Host cell usually rupture, releasing pathogen and also including inflammatory response
Bacterial damage to host cell 3
Production of toxins> fever, CVS disturbance, diarrhoea, shock, inhibition protein synthesis, destroy blood vessels and cells, destroy nervous system > spasms
May be exotoxins or endotoxins
Bacterial damage to host cell 4
Hypersensitivity reactions
Pathogenic properties of viruses 1
Cytopathic effects Prevent production of macromolecules Cell release lysosomes Inclusion bodies Antigenic changes Infected cells adjacent to each other fuse to form giant cell, called syncitium Protection of interferons Chromasomal change in host cell, oncogenes can be activated Contact inhibition may be over ridden
The study of micro organisms
Includes
Bacteriology - bacteria
Virology - viruses
Mycology- fungi
Protozoology- protozoa
Microorganisms
Little creatures
Organisms too small to be seen with a naked eye
Eukaryotes
Prokaryotes
Different types of bacteria
Coccus
Diplococcus
Staphylococcus
Streptococcus
Bacillus
Vibrio
Spirichaetes
Structure of typical bacteria
Capsule
Cell wall
Pilli
Factors necessary for bacterial growth
Nutrition such as proteins and carbohydrates
Water
Temperature
PH
Oxygen
Aerobic
Anaerobic organisms
Binary fission
Where the DNA replicates
Splits into two
Cell separation
The four phases in the culture of bacterial growth curve
Lag
Log
Stationary
Death
Lag phase
Bacteria starts to adapt the new environmental conditions
There is a lot of metabolic activity
Little or no bacteria division takes places
Log phase
Exponential growth phase
Bacteria population increases rapidly
Conditions are optimum growth
Stationary phase
With the exhaustion of nurtrients and accumulation of secondary metabolic production, growth rate slows
The growth rate equals the death rate
Death phase
Bacteria growth decreased with time due to lack of nutrients and toxic metabolic by- products
Bacteria death is greater than production of new ones
