Bacteria Flashcards
Name the 4 ways bacteria can be classified?
Heterotroph get food from outside source
Autotroph make own food
Phototroph energy from sun
Chemotroph energy from chemical compounds
What are bacteria?
Unicellular prokaryotic (don't have nucleus) DNA floats in cytoplasm Asexual reproduction binary fission No mitochondria Rigid cell wall- peptidoglycan
What are saprobes?
Bacteria the feed on decaying material and organic waste
What is aerobic?
Bacteria require O2 to live
What is anaerobic ?
O2 is harmful to the bacteria
What does obligate mean when referring to aerobic or anaerobic bacteria?
Obligate aerobic must have O2 to survive
Obligate anaerobes will die if exposed to O2
What is a facultative anaerobes?
Perform either aerobic or anaerobic respiration but if O2 is present will prefer aerobic respiration. Eg. coliform
Name the 5 shapes of bacteria?
Spherical (cocci) Rod (bacilli) Spiral (spirilla) Comma (vibrios) Corkscrew (spirochete )
What size are bacteria?
0.5-2 um
What is the cell wall of a bacteria made of?
Peptidoglycan- provides protection and prevents cells bursting in hypotonic solutions
What’s the function of capsule?
Keeps cell from drying out and prevent killing by WBC by phagocytosis.
There are 2 types of outer coating on bacteria, what are they?
Made of glycocalyx.
- Slime layer- loosely organised and attached
- Capsule-highly organised and tightly attached
How is nuclear material stored in bacteria?
As circular molecules of DNA or smaller plasmids containing non vital genes
What is a mesosome?
Used for basic cellular respiration.
How do we identify bacteria?
Gram staining
Gram+ stained purple as they have thick cell wall made of peptidoglycan(traps the stain)
Gram- thin cell walls with an outer membrane (Phospholipid). Stains pink after crystal violet washes off. Restain with safranin
How do bacteria reproduce?
Binary fission- main chromosome makes a copy of itself and divides into 2
What are the 4 phases on the bacterial growth graph?
Lag phase
Exponential phase
Stationary phase
Death phase
How do we measure bacterial growth?
Haemocytometer and diluting plate method.
What is generation time?
(Log phase) time required for bacteria population to double.
How is genetic material transferred in bacteria?
Conjugation - copy of DNA travels through tube into recipient where it’s incorporated into the recipients genome
What’s an endo spore?
A thick celled structure that forms inside the cell
Major cause of food poisoning
Survive many years and withstand extremes
Encloses all nuclear material and some cytoplasm.
Give an example of an endo spore forming bacteria?
Most are bacillus Bacillus subtilis highly resistant withstand radiation and high temp Anthrax Botulism Tetanus
What is a communicable disease?
Passed from one organism to another by:
Touch
Air
Drinking water
Give an example of harmful bacteria?
E. coli
Salmonella.
Staphylococcus aureus (menegitis, strep throat, TSS) cause of MRSA
Necrotising fascititis
