Intro To Microbiology Flashcards
Define microbiology
The branch of biology that deals with microorganisms. Includes bacteria, fungi, viruses, parasites and some algae.
What are common traits f microorganisms?
- living compartments that interact with their environment and other cells
- relatively simple structures - less specialised
- take up nutrients from env
What are examples of specific functions that some cells can undertake?
Differentiation, communication, horizontal gene transfer and motility.
Define pathogens and disease.
Pathogens = microorganisms that cause disease.
Disease = when infection causes damage to vital systems of function.
Why are bacteria so important in humans?
They have an important role in metabolism and aid digestion.
What are some examples of specialised features of bacterial cells?
The cell wall dictates how bacteria respond to stimuli
Cytoplasmic membrane acts as osmotic barrier to maintain conc diff
Pili adhere to initiate cell invasion in mammals
What are features of gram positive bacteria?
Cell wall made mostly of peptidoglycan
No outer membrane
Thick, multi layered peptidoglycan layer
Greater mechanical strength
Stains blue/purple
20-30nm.
What are features of gram negative bacteria?
Thinner layer of peptidoglycan in cell wall
Outer membrane present - high lipid and lipoprotein content
Low susceptibility to penicillin
Stains pink/red
8-12nm.
How do bacteria divide?
By binary fission
What are the different bacterial growth phases?
Lag, log, stationary and death.
How does temp affect bacteria survival?
Denatures cell membrane, affecting function.
Classed as thermophiles, mesophiles, psychotrophs and obligate psychophiles.
How does pH affect bacterial survival?
For bacteria, pH 4-9 is the largest range it can grow.
Optimum is 6.8-7.2.
But some are exceptions.
How does oxygen affect bacterial survival?
Vary in need and response to oxygen. Some need it to make ATP, some are anaerobic.
How does nutrient availability affect bacterial survival?
Water, glucose, other organic nutrients and vitamins.
How do toxins affect bacterial survival?
Competition for nutrients, may kill bacteria. Some may produce toxins during division = exotoxins.
Endotoxins are part of the cell and release when it dies.
How can the spread of pathogens be controlled?
Prevention of cross contamination, microbiological analysis, testing and monitoring.
Strict hygiene rules.
