Essay
Unit 16 Assignment A & B - Microorganisms Classification
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- PEARSON (PEARSON)
Distinction graded, not referenced but still with detailed explanations to help :))
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Assignment A&BUnit 16
Classification of Microorganisms
With microorganisms, there are a variety of classifications, and different ways to view them
under different types of microscopes. Within this report, I will be discussing the
disadvantages and advantages of these microscopes, and how to identify the
microorganisms, as well as comparisons between them.
Classification of Microorganisms
Within these microorganisms, they can be scientifically classified. This is called taxonomy.
They are classified in domains and kingdoms. There are 3 domains that microorganisms can
be classified under: bacteria (prokaryotic cell with no nucleus and single called), archaea
(have different RNA and cell walls) and eukarya (eukaryotic multicellular or unicellular
organisms). The domains classify whether an organism is prokaryotic (do not have a nucleus
or membrane bound organelles) or eukaryotic (have a nucleus and membrane bound
organelles).
The kingdoms organisms can be separated under are as follows: prokaryota (archaea and
bacteria), protoctista (protozoa and algae), fungi, plantae and animalia. This is then further
split into phylum or division, class, order, family, genus and species. Microorganisms have
binomial names, much like animal species, in their genus and species.
The way that certain microorganisms also get nutrition can be how they are classified in
bacterial cells, like being autotrophs (produce their own source of nutrition) or heterotrophs
(using plant matter that is decaying for nutrition).
Classification is important within medicine and industry as it allows disease and infection to
be treated (such as identifying and classifying symbiotic bacteria like those of the digestive
system compared to parasitic). This is due to the fact microscopes can also be used to
identify the different structures and be able to classify which type of microorganisms is
present due to said structures. The specific strain and type of organism found can be vital in
changing certain treatments to have the most effective result. For example, with antibiotic
resistant bacteria, the strains which fall under this category should be identified and
classified, so different antibiotics can be used to treat an infection. Microscopes can help
advance this identification in its efficiency by being able to do this. Using the different
microscopy techniques, information such as the behaviour of a specific microorganism can
also be found, as well as the exact genus and species one may belong to.
Bacteria
Bacteria is a prokaryotic cell, meaning it is a cell without a nucleus. Bacteria are sized as
being 0.2-2um. Bacteria can be found anywhere, particularly in dark, moist and warm
environments. These are the ideal conditions that allow cultures of bacteria to grow. A
bacteria cell has 7 major structures:
, ● Capsule - The capsule is the outer layer to the cell wall - it helps support the bacteria
cell to not dry out and offers protection, this is because they are found on bacteria
that cause disease, and it is used as protection against white blood cells.
● Cell wall - These provide a rigidity and structure to the cell. It is made of carbohydrate
cellulose.
● Ribosomes - These are for protein synthesis, they’re made up of protein and two
subunits of RNA (ribonucleic acid). The ribosomes in a bacteria cell are 70S (this
consists of a 30S subunit and a 50S subunit.)
● Nucleoid - The nucleoid holds the DNA of the cell, and it helps to control the activity of
the cell as well as the reproduction. It is also where replication of DNA takes place.
● Flagella - The flagella sticks out of the cell structure and allows for the mobility of the
cell.
● Pilli - Pilli can help the cell adhere to surfaces, it is shorter than the flagella and sticks out
of the cell structure. They can be used as protection against white blood cells.
● Cytoplasm - The cytoplasm is contained within the cytoplasmic membrane and it can
contain things such as different enzymes and amino acids, as well as carbohydrates and
lipids. As well as this, cytoplasm helps bacterial growth, it’s metabolism and removes
waste from the cell.
An endospore is what forms inside the cell, it is a thick
structure. The endospore can be a major cause of food
poisoning. The endospore is effective as it allows the
survival of the cell for many years and in many conditions
- such as in very dry conditions, and boiling and freezing
conditions. This allows for the cell to continue
reproducing and growing in numbers to survive, it also
helps protect against white blood cells.
There are also 5 ways you are able to group bacteria, that
Figure 1 - Showing the different
being spherical, rod, spiral, comma and corkscrew.
● Spherical (cocci) can be multiple different types of illness/disease - such as pneumonia
and food poisoning.
● Rod (bacilli) is rod-shaped, they can be individual (for things like typhoid fever), and
chains (for things like anthrax)
● Spiral (spirilla) is large and can cause things like syphilis.
● Comma (vibrio) is crescent-shaped and can cause things like cholera.
● Corkscrew (spirochaetes) can contribute to diseases such as lyme disease.
Saprophytes are a type of organism that feeds off of decaying matter. This can be things such as
decaying plants or animals. They are useful because ecosystems require them to function - it
helps the nutrients of the decaying matter re-enter the environment and recycles them.
Decomposers allow decaying/dead matter to be broken down into simple chemicals for food.
This is also useful for the environment due to the recycling of nutrients. It allows chemicals to be
reabsorbed by the soil to be used by other organisms. These bacteria can also be classed as
heterotrophic bacteria (feed of decaying plant matter).
Harmful bacteria exist - these are bacteria which carry disease, which may be passed
communicably between one organism to another through touching, sharing food and drink with a
contaminated/ill person and also animals. In order to control these bacteria, a couple of things
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