Environmental Conditions Affecting the Oral Microbiota Flashcards
(92 cards)
How to bacteria replicate?
Reproduce asexually via binary fission
Briefly describe binary fission
Cells circular DNA replicates
Divison of cytoplasm membrane and cell wall follows
Basically the cell splits into 2 daughter cells
How do viruses replicate?
They dont posses the necessary ‘machinery’ to reproduce on their own so they must latch onto a host cell
This allows viruses to use the host cells own cytoplasmic material to synthesise viral components
They are non-cellular organism
Why are viruses described as being non-cellular
Because they are made of nucleic acids (DNA OR RNA)
This nucleic avis is enveloped
It is non-cellular as it doesn’t have a phospholipid membrane
How do yeast cells replicate?
Budding
This is a form of asexually reproduction where a new organism develops from a bud as cell division occurs at a specific site of that cell
How can we measure growth of cells?
Estimate the increase in:
- The number of cells
- The dry mass (dry weight)
- The cellular constituents (eg the increase in ATP)
How can we measure population size?
- Total counts using microscopy
2. Viable counts using colony forming units
Describe the total count method?
Can do a total count using a microscope and a special glass slide called the counting chambers
These counting chambers lets you count the cells in a chamber using a microscope
You can count the number of cells in a chamber and then estimate the total number of organism in the whole population
What is a downside to the total count method?
It does not discriminate between living and dead cells
What is the viable count method?
Allows for the estimation of the living cells in a population
What do you need to be able to successfully cultivate viruses?
You require a living host cell to support viral replication
You can use eggs, mammillary cell, prokaryotic cells
If bacterial colonies on agar appear identical what does this suggest?
They are the same organisms
If bacterial colonies on agar appear distinct what does this suggest?
They are different species
What are the 4 stages in a bacterial growth curve
- Lag phase
- Log exponential phase
- Stationary phase
- Death/decline phase
What is on the y axis on a bacterial growth curve
Log10 colony forming units (CFU)
When does the growth of micro organism change?
When the environmental factors affecting bacterial growth change
What are some environmental facts that can influence bacterial growth?
Host defences Availability of nutrients Temperature Oxygen/redox potential pH Antimicrobial compounds Oxygen, Ph, metabolic product gradients Depends on the site of the mouth the bacteria may be in
What are the 3 categories microbes can be grouped into depending on their optimum temperature?
- Psychrophiles grow best at 20 degrees
- Mesophiles grow best at 35 degrees
- Thermophiles grow best at 65 degrees
What can the temperature rise to when inflammation occurs and what can this do
Can inverse to 39 degrees and this has an effect on the microbial populations
What are the 5 categories microbes can be grouped into depending on their optimum oxygen concentrations?
Obligate aerobe: they require the precedes of oxygen to survive
Facultative anaerobe: they are able to grow in both the precedes and absence of oxygen
Microaerophile: require some levels of atomospheric oxygen
Aerotolerant anaerobe: The bacteria require the absence of oxygen but can tolerate oxygen
Obligate anaerobe
Require the complete absence of oxygen
What are obligate anaerobes?
They are highly sensitive to oxygen
They generate energy without oxygen
They Require sites with low redox potential
What type of environment is the mouth in regard to oxygen levels?
Quite aerobic environment
What are the 5 reactive oxygen species?
Molecular oxygen is not toxic but its derivatives are: Singlet oxygen Peroxide anion Superoxide anion Hydroxyl free radical
How are the derivatives of oxygen formed?
They are by products of cellular metabolism
