Lecture No. 2 Topic: Mitosis and Meiosis
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Pertinent Web Resources:
The following are some supplemental Web links that summarize the processes of Mitosis and Meiosis. These may be of benefit to you.
Questions:
Why are there two separate cell mechanisms for chromosome replication (Mitosis and Meiosis) in cells ?
Are there differences between the prophase stage of Mitosis and Meiosis I ?
Is there a difference in the frequency of meiosis between males and females of a given specie ? Why ?
Is the frequency of meiotic cycles the same among various types of production type animals (e.g., cattle, swine, sheep, chickens, turkeys, and salmonids) ?
What is a chromatid and how does it differ from a chromosome ?
In the process of meiosis, which division is referred to as the reductional division ?
What regulates the processes of Mitosis and Meiosis, is it genes, proteins, a biological clock ?
What is the significance of the following proteins: cohesin, separase, and shugoshin ?
Some terms to be aware of: chromatid, sister chromatid, dyad, tetrad, monad, karyokinesis, cytokinesis, disjunction, synaptonemal complex, polar body, parthenogenesis..
Review in Pierce at the conclusion of Chapter 2: all the Important Terms as they pertain to animals; Comprehension Questions: 1, 5, 7, 8, 10, 11 to 18; 29, & 33.
Interesting News Items:
The following items are for general interest and illustrate applications of genetics. You are not responsible for the content.
September 27, 2005 - Vol. 3 , No. 39 American Scientist Online
....Science in the News Weekly is a digest of science news stories appearing in the mainstream media. It is delivered every Tuesday morning (or Wednesday morning in the case of a Monday holiday) as part of Sigma Xi's public understanding of science program area, in conjunction with American Scientist magazine.
U.K. Panel: Age of Personalized Medicine, Though Promising, Is a Long Way Off
The prospect that people will someday take a regimen of medicines personalized to fit their genetic profiles has been "overhyped," according to a report by the U.K.'s Royal Society. What's more, for pharmacogenetics to realize its by protecting people in developing countries against diseases like malaria, tuberculosis and HIV, governments and the world's research community must close gaps in knowledge and practice, the panel reported.
To develop personalized medicines that fight off those big killers, much of the research must take place in the developing world. But "variations in the laws for conducting genetic research between countries makes it difficult to combine data from across the globe into large-scale clinical trials," U.K. geneticist David Weatherall, who chaired the panel, told SciDev.Net. In addition, some think it's folly for developing countries that have a hard time meeting the basic healthcare needs of their citizens to race after pharmacogenetics.
Still, personalized medicines do "show promise," according to Weatherall, and some advances based on genetic information have been achieved in improving drug efficacy and in limiting adverse drug reactions. And treatment of some cancer patients has already benefited from so-called smart drugs.
Mice With Chromosome 21 May Teach Researchers More About Down Syndrome, Disorders
Researchers genetically engineered mice with copies of human chromosome 21, according to a report in the journal Science. Chromosome 21 is composed of about 250 genes, making it the smallest of the 23 pairs of human chromosomes. About one in 1,000 is born with an extra copy of chromosome 21. That extra copy causes Down syndrome, one of the more common of genetic disorders.
Researchers believe that the technical feat could help them better understand not only Down syndrome itself, but also a whole host of disorders that are seen in all human beings. That's because people with Down are more likely to suffer from heart defects, hearing loss, leukemia, impaired brain development, behavioral abnormalities and early-onset Alzheimer's. By breeding mice with a copy of chromosome 21 the scientists believe they can track the genes responsible for those maladies.
So "it is entirely possible that if we gain insights into what is going wrong in the Down syndrome people, we will also gain insights into what goes wrong during those disorders amongst the rest of us," explained lead researcher Victor Tybulewicz of the National Institute for Medical Health in London.
Tybulewicz and colleagues at the Institute of Neurology had been working toward this achievement for 13 years. In the successful effort they removed chromosome 21 from the nuclei of human cells, then mixed the chromosome with embryonic stem cells from mice. They added a chemical that promoted fusion of the chromosome with the stem cells. Those stem cells that took up the chromosome were then injected into a mouse embryo that was implanted into a mother, who bore a mouse with a copy of human chromosome 21.
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Posted: 8:20 AM, Sept 29