by contrast our sex or germ cells are one haploid that is they contain only half the number of chr. thus the egg cells are 22+X, whereas spermatozoa are either 22+X or 22+Y. hence when egg and sperm fuse at fertilisation the diploid number is restored.
later on we shall see that germ cells have a special form of cell division called meiosis to bring about this reduction in the number of chromosomes. we shall also see that the Y chr. has a vital gene called the testis determining gene (or sometimes the sex determining gene).
in the absence of this gene individuals are committed to being female., .
only those with the TDY (SDG) can ever be made. thus there is a fight to be male with the female being the neutral sex.
there is absolutely constant for the species.
e.g.
Ascaris (threadworm) has 2 or 4 chr.
Drosophila (fruit fly) has 6 to 10.
Felis (cat) has 38.
Pan (chimpanzee) has 48.
Macaca mulatta (rhesus monkey) 42.
Homosapiens (man) has 46.
but.-.
Paramecium has 60-123.
Cyprinus (carp)- has 100-104.
in other words, the number of chr. is not related to the size of the animal.
what is important is the number of genes which in man is at least 100,000.
aneuploidy.
we have just seen that in our species homosapiens, must have 46 chr. in each somatic cell (23 in germ cell- an egg or spermatozoon).
but deviations from this ideal no do occur as a result of errors in the process of cell division. sometimes the homologous pairs of chr. stick together and cannot be separated. thus one sex cell gets two copies of a chr. while the other receives none. after fertilisation the embryo that is formed will have either 45 of 47 chr.
so then one gamete can get a "double dose" of a chr. while its partner gets none. this, after fertilisation, results in trisomy and monosomy respectively for that particular chr. monosmy is normally lethal because the individual lacks one chr. and hence one complete set of genes, but the exception is the X-chr.
The issue of genetics has been around for quite sometime. ... First of all, genetics are moving very fast. ... Nature is part of our world and now we are somewhat working against it because we do not think that it is fit for us as humans. ... The human body is also being helped in this whole process. ... Genetics is surely the highest feat ever accomplished by our human brain. ...
Genetics The first in-depth study of genetics was done by Charles Darwin in the mid 1800s. Since then we have learned, and continue to learn, even more about the fascinating and mysterious world of genetics. ... Each human cell has 46 chromosomes. ... Even today we continue to make more and more discoveries about human genetics. ... The advancements in the study of human DNA and the possibility of human cloning have caused some people to question the ethics of genetic study. ...
Genetics is the study of genes. ... Genetic Engineering is a deliberate effort to develop kinds, and strains, of organisms that would benefit human beings. ... Even though humans have the same genes individuals may inherit different genes, which is what make each person unique. ... Each human seems to be a mixture of traits. ... Genetics is a branch off of biology. ...
Genetics is a powerful field of science, with many possibilities. ... The actual study of genetics started long ago, with Mendel and his studies. Now scientists know much more of genetics and DNA. ... The Austrian Monk Gregor Mendel discovered the basics of genetics. ... Humans must make ethical decisions on what they will allow to happen. ...
Imagine what life would be like if we could eliminate human problems. ... Genetics is slowly paving the road to this utopian vision. Genetics gives us the ability to manipulate DNA, Clone human beings, in short it gives us the power to be Gods. ... All of the previous paragraph leads to the argument which comes up in many other controversial topics, when does a human life begin, when are you a human being. ... Genetic Engineering doesn't necessarily have to be used on humans as I have seemed to focus on, it can also be used on plants and animals. ...
The final one is Human Genome Project. ... What is Human Genome Project? ... Can we choose not to know our genetics information? ... HGP result must improve the techniques on gene therapy and genetics engineering dramatically. ... So we have to look at the concern of gene therapy and genetics engineering. ...
Genetic technologies will help increase the information we already know about genetics in canines. ... Although humans have cross-bred dogs for centuries now, we have just recently gained a true knowledge for it. ... A final technology that can be used in dog genetics is the dog I.Q. test. ... Technologies like this will continue to help the knowlegde and discovery of dog genetics, man's best friend. The specie will continue to improve and have an even better place in the heart of humans. ...
Humans have 46 chromosomes. 1 Illustration of the placement of genes in a chromosome. ... In 1988, an International Human Genome project was set up which began to recognize and identify the 46 chromosomes of every cell. The point of the project is for scientists to have a better understanding of how genetics contribute to human disease. ... Therefore, genetics should be treated the same way as AIDS, if one receives an AIDS pamphlet, one should receive a genetics pamphlet. ... Blood can also be tested to check for genetics. ...
Business Ethics and Human Genetics Throughout history, man has prided itself on the ability to explore our world and to find new and interesting perspectives on life. ... One fairly new concept that is very debatable is the ability for scientists to manipulate human genetics into forming a duplicate cell; this procedure is also known as cloning. ... Until further analysis proves that neither research will intentionally use genetic testing to recreate a human being, government officials are trying to enact a bill criminalizing human cloning (Raeburn pp. 46). ... Even if the human gene is...
The Human Genome Project Does the Human Genome Project effect the moral standards of society? ... Genetics is the study of the patterns of inheritance of specific traits. ... Gregor Mendel, an Austrian monk, completed experiments on garden peas so as to establish the quantitative discipline of genetics. ... These organizations all have two shared objectives, placing "new methods and instruments into the tool-kit of molecular biology" and "building research infrastructure for genetics"(Murphy, 17). ... Thus the moral dilemma of genetics is simple; will it be an asset or an evil to the indivi...
