Bacterial Morphology and Growth Flashcards
Summarise the methods for clarifying bacteria
- Size
- Gross structure
- Cell wall structure
- Differential stains
- Morphology
- Growth requirement
What is the range of bacteria size?
0.3μm - 3μm
Summarise the structural components of bacteria
• Haploid (single chromosome) DNA (circular) • DNA in nucleoid region : NOT bound in a nucleus, • Ribosomes in cytoplasm • Peptidoglycan membrane • No mitochondria • No membrane bound organelles • +/- Capsule • +/- Pilli / Flagella \+/- Spore to sleep,
Summarise the steps in staining bacteria
- Fixed
- crystal violet
- iodine
- alcohol
- carbol Fuschin or Safranin
what does the alcohol do to gram negative bacteria
the alcohol step damages the outer membrane and allows the BLUE/PURPLE crystal violet dye out.
• - The second safranin/carbol fuschin dye then stains the cell wall RED/PINK
What are the colours for gram positive and negative bacteria stains?
- o Gram Positive ▪ Blue/Purple
* o Gram Negative ▪ Red/Pink
How are acid fast stained and what do the stains indicate?
Ziehl-Neelson stain
Use acid not alcohol to wash off stain.
RED or FLUORESCENT if Acid Fast
- NO STAIN if Non-Acid Fast
o Non-Acid Fast = they do not retain the carbol fuschin/auramine stain on the cell surface when washed with acid.
Name 4 gram +ve cocci
- Gram positive cocci in pairs (diplococci) eg. Streptococcus pneumoniae (pneumonia)
- Gram positive cocci (in chains)- Streptococcus pyogenes (pharyngitis)
- Gram positive cocci in clusters Staphylococcus aureus (toxic shock syndrome)
- Gram positive rods (bacillus)- Corynebacterium diphtheriae (diphtheria)
Name 4 gram+ve rods with spores
- Clostridium tetani (tetanus)
- Clostridium perfringens (gangrene)
- Clostridium difficile (pseudomembranous colitis)
- Bacillus anthrax (anthrax)
Gram negative rods (bacilli)…
• Escherichia coli (colitis) Salmonella typhi (typhoid fever)
Gram -ve Spiral (helical) shaped
- Treponema pallidum (syphilis)
- Helicobacter pylori (stomach ulcers)
- Vibrio cholerae (cholera)
Name a bacteria with no cell wall. What does it have instead?
Mycoplasma pneumoniae (atypical pneumonia)
• Have only lipoprotein outer coat
Factors affecting growth(8)
- Division rate
- Lag phase time
- Oxygen availability
- Carbon availability
- Temperature
- pH
- Inhibitors
- Growth Factors
Name a bacteria that are rapid growers
Vibrio cholerae
• Division every 20-40 minutes = 1,073,741,824 bacteria from 1 starting cell overnight
Name a slow grower
- Treponema pallidum (syphilis)
* Division every 30 hours