BIL 104 “Genetics and Society”, Essay Example

Part of the mRNA sequence of an exon (coding region) of a gene that encodes a blood protein is: AUG ACU CAU CGC UGU AGU UUA CGA

Consult the genetic code to answer the following questions:

• What is the sequence of amino acids that this mRNA encodes?

Methionine, Threonine, H istidine, Arginine, Cystein, Serine, Leucine, Arginine

• What is the sequence if a point mutation changes the tenth base from a “C” to an “A”?

AUG ACU AAU CGC UGU AGU UUA CGA

Methionine, Threonine, Asparagine, Arginine, Cystein, Serine, Leucine, Arginine

• What is the effect of a point mutation that changes the fifteenth base from a “U” to an “A”?

AUG ACU CAU CGC UGA AGU UUA CGA

Methionine, Threonine, H istidine, Arginine,

Only four amino acids will be produced since a stop sequence will be initiated at the fifth codon.

• How does the encoded amino acid sequence change if a “C” is inserted between the fourth and the fifth base?

AUG ACC UCA UCG CUG UAG UUU ACG A

Methionine, Threonine, Serine, Serine, Leucine,

A stop sequence will be initiated at the sixth codon thus only five amino acids will be produced.

• Which would be more devastating to the encoded amino acid sequence, insertion of three bases in a raw, or insertion of two bases in a row?

It is better to insert three bases in a row that to insert two bases in a row because with the insertion of two bases, the sequence changes whereas with addition of three bases, an amino acid is added to the sequence therefore it is better to add an amino acid rather than to change the sequence which might bring about mutation.

• The Finnish population has a 1 percent carrier frequency for a seizure disorder called myoclonus epilepsy (MIM 607876). Two people who have no relatives with the illness ask a genetic counselor to calculate the risk that they will conceive an affected child, based on their belonging to this population group? What is their worst possible risk?

Judging by the parents belonging to the population group, it means they are carriers of the myoclonus epilepsy gene. These means that the myoclonus epilepsy gene is recessive in their body thus they are able to pass it down to their offspring even though they cannot experience the seizure disorder themselves. If so, it means that 25% of their offspring will be free of the gene, 50% of their offspring will be carriers of the gene and the remaining 25% of their offspring will suffer from the myoclonus epilepsy and experience the seizure disorder. This means that they have a chance of conceiving one child out of four who will be affected with the myoclonus epilepsy gene. Considering they re from the population with the 1% carrier frequency, it means that there is a twenty five percent chance of this 1% carrier frequency that the 25 percent of their offspring will be born with the disorder. Therefore, the worst possible risk of conceiving a child with the disorder is 0.25%.

• Explains the connection between cancer and control of the cell cycle.

Cancer refers to diseases in which the cells of the body start to divide without control and show abnormal characteristics. These cancer cells invade tissues and spread through the bloodstream and even the lymphatic system. The cell cycle can also be called the cell division and it refers to a series of events that take place in a cell and leads to the cell division, duplication or rather replication. The connection between these two is that during the cell cycle, there are the GO and STOP signals that regulate the cell division and are always influenced by external factors. These signals help in the regulation of cell division. With a cancer cell, these GO and STOP signals are not effective hence the cell division process is not regulated. Cell reproduction continues uncontrollably and it may cause a growth of overlapping cells. Cell cycle is therefore the process through which the cancer cells spread.

• List four characteristics of cancer cells.

1. Cancer cells undergo unlimited number of cell divisions.
2. Cancer cell grow without the external factors that regulate cell division.
3. Cancer cells do not undergo apoptosis or programmed cell death.
4. Cancer cells do not respond to the stop dividing signal sent when there is cell to cell contact.