Does DNA need to be copied every time a new sperm cell is produced ? Do spontaneous mutations occur?

Question

Do mutations lead to genetic defects?

Answer 1

yes [by mitosis];
sometimes;
sometimes, depending on the genes affected

learn about DNA and MITOSIS @:

http://en.wikipedia.org/wiki/Dna
http://en.wikipedia.org/wiki/Mitosis

Answer 2

Sperm cells are produced in a process known as meiosis, where the normal 46 chromosomes are reduced to the 23 which will be carried mature sperm cells. It's not a duplication in the strictest sense, but all of the material found in a sperm cell was originally a copy of the person's DNA. Spontaneous mutations occur frequently, and sometimes they do cause genetic defects. Usually the mutations are harmless, because the defect will be compensated for by the chromosomes donated in the ova. Also, sperm cells which are deformed as a result of mutations are not sucessful in fertilization and that tends to eliminate a good many problems at the beginning. Although we tend to associate mutations with a defect, a good many traits we now consider normal probably were originally mutations. There are also beneficial mutations, which result in people born without appendixes and without wisdom teeth- and possibly even higher intelligence. Not all mutations need be fatal or harmful, and most likely are not.

Answer 3

not only bloody mutations, also trials and errors. By trials nature tries new ways for us to be sucessfull and errors... well we shell drink less...