REVISION, EVOLUTION BY NATURAL SELECTION
30 Monday Jun 2014
Posted case study
in30 Monday Jun 2014
Posted case study
in21 Sunday Jul 2013
Posted case study
inTags
Thien suggested the virus originated in Monkeys. ( the eating of raw monkey brains- a habit amongst some African tribes)
In an epidemiological study this is essential to know as;
It may explain the pattern of the outbreak
It may identify who is at risk
the original host may contain antibodies that can assisting the production of a vaccine.
The other comment made was that it was essentially a gay male disease in San Francisco in 1970.
This was essential information. Doctors studied the lifestyles of the infected people and it became very evident that it was a sexually transmitted disease. Those ill with the mystery illness, all had unsafe sex with multiple partners….some hundreds of parents in short periods of time.
The symptoms were the same, their lifestyles the same, only a small group was infected compared to the whole population of San Francisco.
23 Sunday Jun 2013
Posted case study
inTags
20 Monday May 2013
Posted case study
inScientsists have created an embryo using the DNA from a skin cell of the donor. The embryo is a clone of the host.
Stem cells are undifferentiated or unspecialised cells. The genes in these cells have not yet expressed themselves. Another way to express this is to say, the genes have not been switched on.
Using the correct stimuli, scientists can switch on genes that control the specialisation of the cell. This is outlined below.
This has great potential in curing disease and injuries. For example damaged heart muscle can be replaced with muscle derived from a stem cell.
The creation of an embryo is controversial. Some would claim that it represents a life, and should not be tampered with or used as spare parts.
Concerns also are associated with cloning. Unknown side effects such s premature ageing have been linked to this process. E.g Dolly the sheep.
05 Tuesday Mar 2013
05 Tuesday Mar 2013
Posted case study
in04 Monday Mar 2013
Posted case study
inTags
Can we compare this report with the video we watched on AIDS/HIV?
VARIATION. The baby was treated 48 hours after birth. Assume the only virus present was the mother’s. No resistant viruses were present. The drugs prevented the replication of the virus or killed it in a short time. There was no time for mutations to form resistant viruses.
SELECTION. This is a case of extinction. Hopefully the virus does not survive. The little one has been virus free for some months.
TIME. Even for a microorganism, time is needed for new species to form.
04 Monday Mar 2013
Posted case study
in27 Wednesday Feb 2013
Posted case study, Uncategorized
inSYLLABUS
analyse information from secondary sources to prepare a case study to show how an environmental change can lead to changes in a species.
Our example, HIV AIDS (the video we watched)
TTHE ENVIRONMENTin this case is the blood stream of the patient, particularly white blood cells called T lymphocytes.
(The virus infects the lymphocytes, rendering it useless. It then multiplies and bursts out of the cell to infect others)
THE ENVIRONMENTAL CHANGEis the presence of one or more drugs.
THE CHANGE IN THE VIRUS
In a no drug environment the wild type is favoured. It multiplies quickly and the patient faces considerable danger.
In a drug environment, the wild type are killed and the DRUG RESISTANT SPECIES OF HIV ARE FAVOURED.. Remove the drugs and after a few weeks the wild type returns.