how does DNA mutation occur leading to abnormal birth??

Question

please give answers with respect to genes hereditary and regarding cloning etc....i am very interested in biotechnology so please feel free to mail supportive answers...

Answer 1

Heritable mutations generally occur during the process of DNA replication. DNA replication occurs with the aide of an enzyme known as a DNA polymerase. The enzyme is not 100% accurate all the time, and will introduce errors when copying the original template. The normal error rate for the enzyme is very low due to the fact that the protein has "proofreading" activity (ie:if an incorrect base is inserted, it is removed and the correct base inserted), however errors do occur causing mutations in the DNA. DNA mutations can also occur due to physical stimuli such as UV radiation, chemicals, etc. Some physical mutations may be repaired by the DNA polymerase, but again that enzyme is not perfect. Once introduced, unrepaired DNA mutations become a permanant part of the indivual's DNA makeup and can be passed onto successive generations.

Most mutations which occur have no decernible effect for three possible reasons: 1) the mutation is in the area of the DNA that is not actively translated; 2) the mutation is in an active area of the genome but has no major effect on the protein product produced coded by that gene; or 3) the mutation is in an active area of the genome and has an effect on the protein produced, but the mutation is recessive in nature. Because we inherent half of our genes from each of our parents, there is built into our genome "backups" for most all our genes, so a mutation inherited from one parent can be masked or hidden because the same gene inherited from the other parent is normal and takes up the slack. Trouble arises when you have when both parents have recessive (or hidden) mutations in the same gene. In that instance, statistics indicate that at least 1 in 4 of their children will inherit the mutation from both parents, and this then results in a detectable abnormality in the progeny.

Answer 2

DNA codes genetic information in the form of four chemical bases (cytosine C, thymine T, guanine G and adenosine A). Cells use the DNA to make RNA. RNA is used to make protein. RNA is "read" in three letter groups to determine which amino acids are hooked together to make the protein.

You can swap bases. If a C --> G, an amino acid could be changed from isoleucine to methionine. This could change the shape of the protein. Since the shape of a protein affects the function of the protein, the protein may not work correctly. This kind of mutation causes sickle cell anemia. If a person has one copy of the malfunctioning gene, they have some functional and some nonfunctional hemoglobin protein. They will have some minor problems, but live a normal life. If a person has two copies, all of their hemoglobin is affected and there are serious side effects.

You can add or delete bases. If you are exposed to a planar 2-3 carbon ringed chemical, it can be incorporated into the DNA. By adding or deleting a single base, the code shifts. Let's say the DNA --> RNA should be AAAUUUGGGCCC or aspargine- phenylalanine - glycine- proline
Delete the first A and you get AAUUUGGGCCC which corresponds to aspargine- leucine- glycine
The protein has lost one amino acid and the phenylalanine is changed to leucine. It would be a massive change.

You can add an extra chromosone or lose a chromosone throught nondisjuction. When sex cells decrease their chromosone number from 46 to 23, sometimes two copies of one chromosone end up in one cell and no copies end up in the other cell. Extra chromosones lead to Down's syndrome, Patau's syndrome and Edward's syndrome. A missing X chromosone is called Turner's syndrome.

Answer 3

I would do a little research on DNA and DNA mutations. Basically there is no simple answer as DNA mutations can be caused by many factors. Just as many aliments such as skin rashes are due to heredity or enviromental factors, many others can be caused by drug use, drinking and plain old bad luck - like a 1 in a billion occurrance of a certain type of birth defect.

Answer 4

see offsprings r born wid abnormalities as either the process of meiosis tht forms the gamets is nt proper r wen the ovum r the sperm has sum defect in their chromosomal count . this is boardly classified as 1) structural abnormalities 2) numerical abnormalities . in the 1st case the size of the chromosome differs frm its homologus pair n in the 2nd case the number will differ (it will b either 1 less r 1/more than the diploid condition)