In "Chromosome 8: Self-Interest," Ridley begins the ninth chapter of Genome by quoting Richard Dawkins' The Selfish Gene, which says, "We are survival machines - robot vehicles blindly programmed to preserve the selfish molecules known as genes. This is a truth that still fills me with astonishment" (122). Ridley goes on to explain that 97% of the human genome are not true genes but are junk or selfish DNA, which is "not just a passenger, whose presence adds to the size of the genome and therefore to the energy cost of copying the genome" (128). Also, selfish DNA threatens "the integrity of genes" (128) through mutation. Ridley ends the chapter with an account of the Pitchfork case - where two identical samples of semen from the bodies of two girls who had been raped and killed helped to find and convict the murderer, proving the value of genetic fingerprinting.
Sunday, June 3, 2012
AP Bio: Genome Blog 6, Chromosome 7: Instinct
In "Chromosome 7: Instinct," Ridley begins the seventh chapter of Genome by saying that there is a gene on chromosome 7 that "pays an important part in equipping human beings with an instinct...that lies at the heart of all human culture" (91). He goes on to explain that instinct is a word used to describe animals whereas humans don't rely on instinct and that "everything they do is the product of free will, giant brains and brainwashing parents" (91). Ridley establishes that although society thinks that "to believe in innate human behaviour, is to fall into the trap of determinism, and to condemn individual people to a heartless fate written in their genes before they were born" (91-92), practically everything is determined by genes, including language. Ridley argues that there is "a set of innate mental rules" (95) in a child that allows the sentences of a four-year-old to be organized in a logical way. Also, Ridley goes on to conclude that the instinct for language is an evolutionary adaptation for "clear and sophisticated communication between individuals" (104).
Anatomy and Physiology: Different Pathogens
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| A cholera bacterium. |
Bacteria
Bacteria can adapt very well to environment that change constantly because they have short generation spans. During these short generation spans, they can undergo genetic recombination. This way, so when they reproduce through various ways such as transformation, transduction, and conjugation, the new DNA will replicate along with their own original DNA. These new, foreign DNA are expressed in the new strains of transformed bacteria. This also lets each bacterium adapt their metabolic processes with the changes of their environment.
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| The structure of the HIV virus. |
Virus
Unlike bacteria, virus are not actually alive because they cannot survive outside a host. They are basically just genes in a protective coat. The parts of a virus includes its capsid, protein coat, viral envelope, and nucleic acid. Bacteriophages are the group of viruses that can infect bacteria. They reproduce through the lytic and lysogenic cycles. In the lytic cycle, they attack the host cell and when the cell bursts, the new viruses move on to destroy other host cells. In the lysogenic cycle, the virus may lie in wait in the host cell for a long time before the lytic cycle is activated and it destroys the host cell.
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| The structure of a prion. |
Prion
Prions are simple infectious agents. They are protein that is misfolded but have no genetic material. Although they are proteins, they can reproduce on their own and become infectious agents. In humans, they may have been linked with the Creutzfeldt-Jakob Disease (CJD) and the Gerstmann-Straussler-Scheinker Syndrome.
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| Symptoms of hemophilia, a genetic disorder |
Genetic
Genetic diseases are caused by an abnormality in person's genome. This could result from a small mutation (ex: single base in DNA of a single gene) to a large mutation (ex: addition or deletion of entire chromosome). Some genetic disorders are inherited from the parents but some are also caused by acquired changes and mutations in the genes. An example of a genetic disease is hemophilia, which is sex-linked.
Environmental
Environmental diseases are caused by factors in the environments, such as pesticides, chemicals, radiation, and pollution.The chance of a person developing a environmental disease depends on the dangers of their environment and their genetic susceptibility to certain dangers. For example, coal miners are more susceptible to black lung due to the inhalation of dust. Proper safeguard can prevent environmental disease.
Invertebrates
Some diseases are caused by invertebrates. Many invertebrates carry diseases; for example, mosquitoes often carry and spread yellow fever and malaria. Some of these disease-causing invertebrates are parasitic. One example are ticks, which can cause Lyme disease.
Sources:Genetic diseases are caused by an abnormality in person's genome. This could result from a small mutation (ex: single base in DNA of a single gene) to a large mutation (ex: addition or deletion of entire chromosome). Some genetic disorders are inherited from the parents but some are also caused by acquired changes and mutations in the genes. An example of a genetic disease is hemophilia, which is sex-linked.
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| Lung infected with black lung disease. |
Environmental
Environmental diseases are caused by factors in the environments, such as pesticides, chemicals, radiation, and pollution.The chance of a person developing a environmental disease depends on the dangers of their environment and their genetic susceptibility to certain dangers. For example, coal miners are more susceptible to black lung due to the inhalation of dust. Proper safeguard can prevent environmental disease.
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| Rash caused by Lyme disease. |
Invertebrates
Some diseases are caused by invertebrates. Many invertebrates carry diseases; for example, mosquitoes often carry and spread yellow fever and malaria. Some of these disease-causing invertebrates are parasitic. One example are ticks, which can cause Lyme disease.
http://www.trupela.com/wp-content/uploads/2009/09/cholera-bacteria.jpg
http://www.scientificamerican.com/media/inline/F1C30FB9-F95F-8B4E-9FAF03A0503D1ABA_1.jpg
http://www.flickr.com/photos/ajc1/464066753/
http://www.doctortipster.com/wp-content/uploads/2011/11/Hemophilia-Symptoms.jpg
http://images.paraorkut.com/img/health/images/b/black_lung-580.jpg
http://images.paraorkut.com/img/health/images/l/lyme_disease_rash-55.jpg
http://www.medicinenet.com/genetic_disease/article.htm
http://www.humanillnesses.com/original/E-Ga/Environmental-Diseases.html#b
Thursday, May 31, 2012
Anatomy and Physiology: Disease Awareness
During class, I have become more aware of salmonella. Before taking this class, I did not exactly know what salmonella is. Salmonella are bacteria that can cause food poisoning. It can also cause diarrhea and typhoid fever. Salmonella infections are most commonly caused by contaminated food. After learning this, I started to eat less medium-rare cooked meat and more well-cooked meat. By cooking meat for a longer time, it kills off more of the bacteria and contaminants in the meat and greatly reduces the chances of being infected with salmonella.
Anatomy and Physiology: The Humoral and Cell Mediated Immune Responses
Humoral (Antibody-Mediated) Immune Response
When there is a first exposure to an antigen, these free antigens activates B cells. The lymphocyte "switches on" and undergoes clonal selection, which is when the lymphocyte grow and multiplies rapidly to form many identical cells called clones. This clone formation is the primary humoral response. Most of the B cell clone members become plasma cells, which produce the same highly specific antibodies. The plasma cells die off after 4-5 days and the antibody level in the blood goes down. There are some B cell clone members that don't become plasma cells but instead, become memory cells that can respond to the same antigen later. As a result, in later immune responses or secondary humoral responses, the response to the presence of the antigen is more faster, prolonged, and effective.
Cellular (Cell-Mediated) Immune Response
In the cellular immune response, T cells are sensitized by binding to an antigen and a self-protein on the macrophage surface. After clonal selection, clone members differentiate into memory T cells and effector T cells. There are several different classes of T cells: cytotoxic (killer) T cells, helper T cells, memory T cells, and suppressor T cells.
Cytotoxic (killer) T cells: directly attack and kill infected and cancerous cells
Helper T cells: binds with specific antigen presented by a macrophage; stimulates production of other immune cells (cytotoxic T cells and B cells); acts directly and indirectly by releasing lymphokines
Memory T cells: descendant of a T cell; forms during initial immune response (primary response); may exist in the body for years to allow it to respond more quickly to later infections by the same antigens
Suppressor T cells: slows or stops activity of B and T cells when the infection or attack has been conquered
Sources:
Elaine N. Marieb's Essentials of Human Anatomy and Physiology, Eighth Edition
When there is a first exposure to an antigen, these free antigens activates B cells. The lymphocyte "switches on" and undergoes clonal selection, which is when the lymphocyte grow and multiplies rapidly to form many identical cells called clones. This clone formation is the primary humoral response. Most of the B cell clone members become plasma cells, which produce the same highly specific antibodies. The plasma cells die off after 4-5 days and the antibody level in the blood goes down. There are some B cell clone members that don't become plasma cells but instead, become memory cells that can respond to the same antigen later. As a result, in later immune responses or secondary humoral responses, the response to the presence of the antigen is more faster, prolonged, and effective.
Cellular (Cell-Mediated) Immune Response
In the cellular immune response, T cells are sensitized by binding to an antigen and a self-protein on the macrophage surface. After clonal selection, clone members differentiate into memory T cells and effector T cells. There are several different classes of T cells: cytotoxic (killer) T cells, helper T cells, memory T cells, and suppressor T cells.
Cytotoxic (killer) T cells: directly attack and kill infected and cancerous cells
Helper T cells: binds with specific antigen presented by a macrophage; stimulates production of other immune cells (cytotoxic T cells and B cells); acts directly and indirectly by releasing lymphokines
Memory T cells: descendant of a T cell; forms during initial immune response (primary response); may exist in the body for years to allow it to respond more quickly to later infections by the same antigens
Suppressor T cells: slows or stops activity of B and T cells when the infection or attack has been conquered
Sources:
Elaine N. Marieb's Essentials of Human Anatomy and Physiology, Eighth Edition
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