Prokaryotes and Viruses
1. Eukaryotic cells tend to be complex in nature. They make up the structures of complex organisms such as animals, plants, fungi and protoctista. The name eukaryotes itself means ‘true-nucleus’,1 this is because of the nature of its DNA being enclosed in a nuclear membrane. This leads to one of the features that make eukaryotic cells distinctive. That is compartalization; this is very distinct in eukaryotic cells this is the separation between different organelles and groups. The organelles maintain their groups to ensure processes such as respiration and protein synthesis don’t mix chemicals. Various compartments are nucleus, plasma membrane and cytoplasm.
Leading on from compartalization the cell structure it is quite complex, it consists of a various organelles that may differ depending on the organism the cells are in. Normally they contain organelles such as nucleuses, mitochondria, ribosome’s and countless others. Eukaryotic cells are also able specialize, this is when cells adapt to their environment and perform specific processes and actions, such as the red blood cell which carries oxygen or the nerve cell which carries impulses.2
2. Gram staining is a method of staining used to indentify and classify different bacteria. The process itself is used to differentiate between two major cell wall types present in bacteria. These are gram negative and gram positive. Gram-negative bacteria having cell walls that contain small amounts of peptidoglycan and lipopolysaccharide, where as gram-positive bacteria have large amounts of peptidoglycan and no lipopolysaccharide.3 The process itself is as follows. First a sample of must be obtained then heated to actually kill the bacteria so it can be worked on. Then after placing on the slide the sample is covered with Gentaian violet, a dye, then rinsed with water. Then the smear of bacteria is rinsed with Gram’s solution, which is a mixture of iodine, Potassium iodide and water in specific proportions. The iodine in the solution reacts with the violet solution developing it into a deep blue-black colour.
The smear is then rinsed with ethyl alcohol to decolorize it. Then it is treated with a compound that stains Gram-negative cells a colour that’s is opposite the blue-black colour of Gram-positive cells, the Gram-positive bacteria are unaffected by this counter stain. So upon looking through a microscope Gram positive bacteria will remain blue-black whilst Gram-negative bacteria will appear clear so must be counterstained then rinsed off with water then blotted. Finally a drop of immersion oil is placed on the smear so as to allow light to pass through. Upon inspection under a microscope Gram negative appear reddish coloured.4
This method is a very suitable method for indentifying bacteria but it is not perfect as there are so bacteria that do not simply adhere to the regulations of the Gram staining and are not easily identifiable. Over all it is a useful technique.
3. . Streptococcus pyogenes has a threadlike spherical structure and is cocci shaped
. Corynebacterium diphtheriae has a palisade structure which is mainly rod shaped
. Treponema pallidum this spiral shaped
.Actinomyces – long strands called filamentous.
.Vibrio cholerae these are comma shaped rods
. Nesseria gonorrhoea- are double shaped spherical shapes.
4. Viruses are not considered to be living organisms. This is because they do not carry out any of the life processes that define an organism. These are movement, respiration, sensitivity, growth, reproduction, excretion and nutrition. They are parasites. For them to reproduce they must take over a host cell. This is their only way to survive.
5. A vaccine is typically a harmless form of a microorganism or an inactive toxin retrieved from bacteria, either way it is harmless to the body. It is used to obtain immunity against certain pathogens, if administered correctly it can help to stop the reoccurrence of certain diseases and sicknesses. A vaccine is normally introduced into the body, because it is a harmless form of a microorganism it doesn’t harm the body, but because the body’s defenses still see it as a foreign particle, the white blood cell make antibodies to attack it. As a result antibodies for that specific microorganism become present in the body, ready to attack in the future if the microorganism should enter the body. This entire process is done to acquire immunity.
6. Synergy is known as cooperation of two or more individuals; in a synergistic relationship organisms can co-habit together and benefit from each other’s presence. An example is that of the bacteria in a cow’s stomach. The bacteria help the cow to digest plant material such as cellulose and in return the cow provides the bacteria with food. This is also known as symbiosis. A parasitic relationship is one where one of the organisms is of detriment to the other’s health, in essence only one-person benefit from the relationship. An example of this is a tapeworm in intestine of a pig. The tapeworm feeds on the pigs digested food by absorption; this in turn weakens the pig and may even cause adverse effects. The main difference between the two is that in a parasitic relationship only one-person benefits and in the synergistic relationship both parties benefit.
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