Bacteria Flashcards
Bacteria
Unicellular prokaryotes (no true nucleus or membrane bound organelles), located in the monera kingdom
2 Bacterial kingdoms
Eubacteria (true bacteria) and Archaebacteria (ancient bacteria)
BACTERIA STRUCTURE: Eubacteria
- 100nm to 10 000nm
- different shapes
cocci = spheres
bacilli = rod shaped
spirilla = corkscrew shape
vibrios = comma shaped - occurs in pairs (diplo), chains (strepto) and clusters (staphylococci)
Cell wall
Protects the cell and gives it shape
Outer membrane
Protects the cell against some antibiotics (only gram negative)
Cell membrane
Regulates the movement of materials into and out of the cells
Contains enzymes important for cellular respiration
Cytoplasm
Contains DNA, ribosomes and organic compounds that are important for life processes
Chromosome
Carries the genetic information obtained or inherited from past generations
Plasmid
Contains some genes obtained through genetic recombination
Capsule
Protects the cell and helps it attach to other surface
Endoscope
Protects the cell against harsh environments
Pill
Assists the cell in attaching to other surfaces
Flagellum
Responsible for moving the cell
Eubacteria
Heterotrophic
Aerobic (oxygen needing) or anaerobic (doesn’t need oxygen)
Gram Tests Eubacteria
- Gram positive = turns purple, not pathogenic
*Gram negative = reddish-pink, pathogenic
Photosynthetic bacteria
Contains chlorophyll so are therefore autotrophic. Food is manufactured from radiant energy and carbon dioxide
eg cyanobacteria
Chemosynthetic bacteria
Autotrophic, obtain energy by oxidising iron or sulphur through chemosynthesis
Heterotrophic
- saprophytic
- parasitic
- mutualistic
- commenalistic
Saprophytic bacteria
Acquire nutrients from decomposing organic matter
Parasitic bacteria
Feed on a living host and cause disease
Mutualistic bacteria
Live with other species so that both benefit
Commenalistic bacteria
Obtain nutrients from other species without causing them harm
Binary Fission
- Bacterium reaches full size and divides to maintain the critical surface area to volume ratio
- DNA replicates
- Nucleoid separates into two parts, each containing complete DNA
- Cytoplasm constricts by the inward growth of cell membrane and divides into two equal parts by cytokinesis
- Cell wall develops and separates bacteria into two identical daughter cells
Growing bacteria in lab
Bacteria is grown in agar containing nutrients. Growth medium and the bacteria are sterilised to avoid infection. In addition the medium in which bacteria are grown is liquid or mixed with agar to form a gel that can be spread. Once bacteria is in growth medium, left for a few days to enable bacterial growth.
TB - mycobacterium tuberculosis
Rod shaped bacteria 2 - 4 micrometres in length. Affects almost every organ but especially the lungs
Primary tuberculosis
No symptoms.
The immune system traps the bacteria as they have such thick walls so w.b.c cannot kill them.
TB can be dormant for 30 years
W/o treatment bacteria destroys lung tisue and causes the accumulation of fluid in the pleural cavity (.) lungs and chest wall
TB and HIV
HIV weakens your immune system greatly. If someone has dormant TB and gets HIV, TB becomes active and can kill person
Treatment of TB
Treated with antibiotic drugs
Governments introduced DOT (directly observed treatment)
- employs community health worker from local community to observe TB patients taking meds
- trained in TB treatment and educated above preventing infection and transmission of disease
- ensure patients finish correct drug course and educate communities
MDR (multiple drug resistant) and XDR (extreme drug resistant) TB
TB becomes resistant if patient has not completed full course of antibiotics / hasn’t received correct meds.
MDR = TB resistant to at least two of primary drugs
XDR = TB doesn’t respond to three or more dugs
Confirming TB
- Lung x-ray - visible patches of scarred lung tissue
- Mantoux tuberculin skin test - small amount of dead TB injected into arm. If person exposed to TB, body produces antigens which cause raised red lump two days after injection. Cannot differentiate between latent and active TB
- Phlegm tissue culture = sample of sputum taken from patient and cultivated under sterile conditions. TB colony = active TB
Preventing TB
Vaccinations, TB patients should not be around others who have compromised immune systems, healthcare workers treated regularly, healthy diet and exercise regime + avoid crowded areas.
