Cell Biology Essay Example

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Question 1

The salmonella chromatic agar contains peptones and nutrient extracts together with esterase substrate. When substrate is placed on the plate, the growth of the eccentric pathogens results into hydrolysis of ester, leading to the production of a brightly coloured phenol that remains in the colonies. After an incubation of 24 hours, under 37 to 42 degrees Celsius, the eccentric pathogen colonies becomes burgundy coloured in a transparent yellow background (Greka & Mundel, 2012). However, the normal flora appears white, cream, yellow or transparent. It is through the changes in colour that the eccentric pathogens can be distinguished from the normal flora when using the salmonella chromatic agar plate.

Question 2

HIV infection has three distinct phases which includes acute seroconversion, asymptomatic infection and AIDS. At the first stage, langaherns cells are targeted together with the CD4+ lymphocytes. The spread to other tissues start occurring rapidly with the absence of any treatment. At the second stage, viral load increase and the CD4+ cell count drops. The viral replication also increases rapidly due to lack of treatment. The patient also experiences persistence in the viral load and it leads to the third stage which is AIDS (Lamond, 2012). The immune system is damaged at this stage due to the lack of treatment and the CD4 count drops further. The signs and symptoms are also evident at his stage which leads to the death of the patient.

Question 3

The parasite is injected in the form of sporozites in the human bloodstream by a female anopheles mosquito. The parasite travels to the liver and invades the liver cells. The growth of the sporozoites takes place leading to the production of thousands of haploid forms known as merozoites. This usually takes place within 5to 16 days. The merozoites then exit the liver and enter the blood stream leading to the invasion of the red blood cell. This leads to the illness and malaria complication that can last for months. The merozoite infected blood leads to the sexual form of parasite leading to further multiplication and formation of gametocytes (Greka & Mundel, 2012). The gametocytes are ingested in the mosquito when it bites an infected human. After growth and division, sporozites are formed in the body of the mosquito and the cycle restarts with a mosquito bite.

Question 4

The wet weight measurement involves measuring the microbial growth by measuring the cell mass with a wet pellet. The dry weight measurement involves measuring the cell mass with a dry pellet. The absorbance method involves measuring the microbial growth through the use of a spectrophotometer (Lamond, 2012). The total cell count method involves measuring the microbial growth by counting total cell number of microbes present in a sample. The viable count involves determining the number of cells capable of forming colonies on a suitable medium. Coulter counter involves the use of an electronic device.

Question 5

The innate and adaptive immune systems have humoral immunity components as well as the cell mediated immunity components. The adaptive immune system is highly specific when it comes to a specific pathogen while the innate immune system is not (Lamond, 2012). The adaptive immune system has the potential of providing long lasting protection while the innate immune system does not. The adaptive immune system also has the ability of destroying the invading pathogens and all the toxic molecules that they produce.

Works Cited

Lamond, Anderson. Advancing Cell Biology through Proteomics in Space and time (PROSPECTS). Molecular & Celular Proteomics, Volume 12, (2012).

Greka, Ann & Mundel, Peter. Cell Biology and Pathology of Podocytes. Annu Rev Physiol, 2012, 74: 299-323.