are mutations in DNA always deleterious?

Answer 1

Of course not.

The vast majority of mutations do absolutely nothing. Some are harmful, others are beneficial.

Answer 2

Nope, DNA mutations aren't always deleterious. There are point mutations, where one nucleotide changes to another--nothing deleted, but a base gets changed. If the base that gets changed is still suitable to produce the amino acid that the triplet it's in produced, it's okay, but if not, the triplet can mess up the protein by producing either the wrong amino acid or a stop codon.

You can also have indel or insertion/deletion mutations, where a base is either inserted into or deleted from a sequence; those cause frameshift mutations, since removing or adding a base will screw up which amino acids get produced from the sequence.

Then there are inversions, where a section of DNA gets taken out, flipped around, and reinserted, which also messes up the protein produced by the sequence, since an entire segment has been changed.

Answer 3

Asides from the possibility of bacteria and viruses, I do not believe that there has been any recorded beneficial mutations in humans or any other living thing that added beneficial genetic material.

If one were to argue that there was a beneficial mutation, it is usually because of a loss of genetic information. For example, there are shrimp that can't see a thing that live in caves, but these shrimp have lost genetic information that allows them to see. They may be adapted to the environment of the cave, but they lost something that their descendants probably will never gain back: sight. So, if the environment changes and these shrimp are put into an environment that requires sight, then they are no longer going to survive.

The above may be a poor example, but I do not believe I have ever read of an observable, beneficial mutation taking place in DNA, except for the possibility of viruses and bacteria adaptations.

In other words, the answer is "no" if you are talking about single celled organisms, other than that, someone would have to show me a study that observed a multicellular organism changing its DNA for the better and prove that the adaptation wasn't already encoded in the natural genome.

As for the study noted by Ray, sickle cell anemia is a mutation that keeps you from contracting malaria, however, I do not consider it beneficial, since people *suffer* from sickle cell and the mutation most likely was not initiated as a response to malaria. It's like saying you can't get nail fungus if you don't have toes, or a hemophiliac, another genetic mutation, cannot die from a blood clot blocking a blood vessel.

SCA greatly increases the chances of a shorter lifespan and suffering from post-(auto)splenectomy infection, stroke, gallstones, spleen problems, and bacterial infections. SCA is a draw back, which, in my book, is always going to be a draw back even if it does prevent the contraction of malaria.

Answer 4

No. For every mutation that is deleterious, there is obviously a reverse mutation that is beneficial.

And unless there is some exterior force judging which mutations to allow and which to disallow, any mutation is just as likely as its reverse.

Answer 5

Hmmm... deleterious for one group, for one situation but not for another?

The following is plagiarized, Apparently for most people sickle cell anemia is most definitely a draw back, however I will take it if you throw me in a tent of malaria ridden mosquitoes. I am not sure, but I think that I read somewhere that if one of the parents carries the sickle cell gene and not the other, the mutation is positive to the offspring as they have some resistance to malaria but not sickle cell, but you know...... I am probably wrong on that part too :-)

See source
Sickle cell anemia is the most common inherited blood disorder in the United States, affecting about 72,000 Americans or 1 in 500 African Americans. SCA is characterized by episodes of pain, chronic hemolytic anemia and severe infections, usually beginning in early childhood.

SCA is an autosomal recessive disease caused by a point mutation in the hemoglobin beta gene (HBB) found on chromosome 11p15.4. Carrier frequency of HBB varies significantly around the world, with high rates associated with zones of high malaria incidence, since carriers are somewhat protected against malaria. About 8% of the African American population are carriers. A mutation in HBB results in the production of a structurally abnormal hemoglobin (Hb), called HbS. Hb is an oxygen carrying protein that gives red blood cells (RBC) their characteristic color. Under certain conditions, like low oxygen levels or high hemoglobin concentrations, in individuals who are homozygous for HbS, the abnormal HbS clusters together, distorting the RBCs into sickled shapes. These deformed and rigid RBCs become trapped within small blood vessels and block them, producing pain and eventually damaging organs.

Answer 6

There is no proof of Animals or Humans evolving. Evolution hasn't and I don't believe ever will be proven. Look up creation science and you will see that evolutions theory's are old and outdated fairy tales.

Answer 7

nope .... without DNA mutations, humans would never have evolved

Answer 8

no. Some are beneficial and spread through population leading to evolution.

Answer 9

Hi. No, because that is what causes creatures to evolve.

Answer 10

no some are for the species survival