Biology B3 Part 4

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  • Created by: Sam
  • Created on: 18-04-12 19:09

Based on edexcel textbook

pg 34-35 Artemisinin and Taxol

Artemisinin is used to treat malaria in south-east asia extracted from the leaves of the Artemisia annua. Artemisinin kills the parasite plasmodium that causes malaria. It also prevents reproduction of the parasite so reduces trasmission from person to person. It is only effective in the body for a few hours but combined with other anti-malarial drugs it can be very effective. The combination treatment is called artemisinin-based combination therapy (ACT) and is recommended by the World Health Organisation for areas where chloroquine is not longer effective. A shortage of artemisia leaves led to scientist tryingto make artemisinin. Genetically engineered yeast cells produce a similar substance that can easily be converted and is more effective. It could also be useful in the treatment of cancer.

Taxol is a substance produced from the bark of the pacific yew tree. The structure of Taxol was worked out in 1971 by 1980 the effect of taxol was understood. It stops cells from dividing affecting cancerous cells more than healthy ones. This makes it a good anti-cancer treatment. Unfortunatly the tree is the slowest growing in the world, only a small amount of taxol can be extracted and the tree dies in the progress. Luckily a similar substance was found in the needles of the european yew tree which can be modified to make paclitaxel a semi-synthetic copy of taxol. It became avaliable as a treatment in 1995 but producing it is costly so scientist hope to be able to synthesis taxol completely or to harvest it from culture grown yew cells in the future.

pg 36-37 Stem Cell Research

Once fertilsed egg cells divide in two by mitosis and the cells continue to divide until a hallow ball of cells called the embryo develops. The cells on the inside of the ball are all stem cells. They are unspecialised but a divison continues they begin to change until they make up all the different types of cell in the body (differentiation) but even as adults some stem cells remain eg. in the bone marrow to give rise to new blood cells. It is likely that small amounts…

Comments

Rebecca Davies

This is way to complicated! these are NOTES , not copies of the textbook!

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