Mutations and Genetic Disorders
Creation Ministries International asks - 'How could mutations - accidental copying mistakes (DNA 'letters' exchanged, deleted or added, genes duplicated, chromosome inversions, etc.) - create the huge volumes of information in the DNA of living things?
How could such errors create 3 billion letters of DNA information to change a microbe into a microbiologist? There is information for how to make proteins and also for controlling their use - much like a cookbook contains the ingredients as well as the instructions for how and when to use them. One without the other is useless. Mutations are known for their destructive effects including over 1,000 human diseases such as haemophilia. Rarely are they even helpful. But how can scrambling existing DNA information create a new biochemical pathway or nano-machines with many components, to make 'goo-to-you' evolution possible? E.g. how did a 32-component rotary motor like ATP synthase (which produces the energy currency, ATP, for all life) or robots like kinesin (a 'postman' delivering parcels inside cells) originate?
ANY DAMAGE TO DNA IS A MUTATION
Why do we have mutations in our DNA? The Bible is quite clear on that. Whilst safe when in the Garden of Eden, once Adam and Eve were banished, the Earth was cursed and became prone to corruption. DNA was no longer totally protected for future generations. The fall set the stage for mutation and random errors to develop in DNA and the expression of hitherto 'silenced' genes - such as those for making thorns. It’s interesting that Genesis 3:17 states that God cursed the ground for our sake! Why? So that we would call upon His name in our distress.
Genetic mutations arise from three major causes. I refer you to the previous two articles on genes and chromosomes.
1. You may remember that, when a chromosome or chromatid duplicates itself during the early stages of cell division, the new copy of the chromatid remains attached to the original chromatid somewhere towards the middle forming the familiar X shape. When the cell divides into two the two chromatids of the X are pulled apart so that each cell will end up with one chromatid. In human cells there are a total of 46 chromatids, 23 from the father and 23 from the mother.
We received our DNA from Adam and Eve. The fidelity of DNA replication of our chromosomes is amazingly high, but just occasionally a rare error may occur as the DNA is copied despite any precautionary measures the cell takes.
Accidental errors may be introduced while a chromatid is being copied in readiness for cell division. For example, a ‘T’ might be substituted for a ‘C’ or perhaps left out altogether. It takes three letters in correct order to specify a particular amino acid. Usually, when DNA is replicated, any errors during replication are immediately corrected by a proof-reading enzyme. Don't you find that absolutely amazing? On rare occasions, the error is missed and then it will be passed on to all future generations of the cell within the tissue. If the mutation occurs during the formation of a sperm or egg cell then the mutation can be passed on to the children. The error is inherited.
2. Accidental errors in the coding region of a gene, if serious enough, may cause the protein that it generates dysfunctional. If it were not for the fact that all genes are duplicated like XX or XY, it could become a fatal mutation. Duplication provides redundancy in our genetic makeup which safeguards us from more serious harm. Duplicated genes explain why some people are carriers of a genetic disease, but they themselves don’t suffer harmful physical effects. Carriers don't show the symptoms. Haemophilia is such an instance.
3. The DNA in living cells can be ‘knocked about’ by environmental toxins, radiation, etc. That’s why pregnant ladies are not allowed to work with significant sources of radiation. Sunlight and UV is a class of radiation. The DNA in the cells can be damaged i.e. mutated. If cells lose their regulatory sequences they may begin to grow in uncontrolled fashion, and invade other tissues becoming cancers. Cancer is the loss of regulation that is a normal property of cells. Cancer cells divide rapidly and no longer ‘sense’ their allocated position in the body. They metastasize or move to other regions, through the lymphatic system or in the blood, because they have been able to cross barriers that beforehand would have restricted them.
They can penetrate other tissues having lost their sense of coming into contact with other tissues. Contact inhibition is another biological miracle of the Lord. Contact inhibition prohibits the diffusion or migration of unwanted cell types into prohibited areas. The photo shows dividing breast cancer cells that can move about to the nearest blood supply for its oxygen needs. They also promote vascular growth towards themselves by disrupting the normal distribution of arteries and veins.
This diagram shows the case of an X-linked, carrier mother for Haemophilia. The haemoglobin gene resides on the X sex-determining chromosome. A defective haemoglobin gene (white box) cannot be complemented by a normal haemoglobin copy of the gene in males who can only have XY-paired sex chromosomes. Because females have XX-paired chromosomes they are likely to be carriers of the disease or can show symptoms if both of their X sex chromosomes are mutated. Males with the mutation on the X chromosome will show symptoms of haemophilia. X chromosomes that are defective are not marked with an ‘X’ (Diagram from Wikipedia, GNU Free documentation licence).
Let’s consider another mutation in a damaged gene that causes cystic fibrosis, a serious syndrome. There is a mutation (named q31) in the DNA of the CFTR protein gene which resides in chromosome 7. The mutation is an unfortunate change in the DNA coding sequence of this gene hence the protein that results from it will have a slight change in its amino acid composition, which renders the protein useless for its intended purpose. As shown in the schematic diagram, CFTR is a trans-membrane protein that functions to transport chloride ions across the membrane. Note how the protein is firmly nestled within the membrane, spanning both sides. Loss of the chloride transport channel causes cystic fibrosis.
CFTR is a particular type of chloride channel across the membrane of cells that produce mucus, sweat, saliva, tears and digestive enzymes. Mutations of the CFTR protein lead to loss of regulation of epithelial fluid and chloride ion transport in the lung, pancreas and other organs. Complications include thickened mucus in the lungs with frequent respiratory infections and pancreatic problems leading to malnutrition, and diabetes. Cystic fibrosis can become chronic and reduce life expectancy.
Severe exposure, after the use of uranium-tipped armour piercing shells in the Gulf war and escaping toxic gases, such as the methyl isocyanate industrial accident in Bhopal, India, has caused untold misery because of damage to genes or to developmental processes causing birth of physically and mentally disabled children. I have seen photos of children born with one eye, no mouth or an eye where an eye should not be. The master genes for these organs were affected, no longer able to regulate positions in the body where these genes ought to be expressed.
These mutations can be mimicked in the laboratory by exposing rapidly breeding fruit flies to radiation. Wings, legs and antennae grow in the wrong places, even out of the eye. This surely emphasizes how wonderfully God pre-programmed the DNA of the normal human body and the consequences of sin when things do not go according to plan.
Diagram A. X-ray image of a 7-digit hand.
There is one extra fleshy little finger (i) and an additional large digit (ii) joining from well below the wrist. Skeletally, there are 6 fingers (Traced from Wheeless' Textbook of Orthopaedics, 1996). Other birth deformities include limbs with 10 digits, doubled lungs, gross hare-lips, doubled thumbs that look like forks, hands that look like lobster claws etc. © 2005 Franc Podgoršek/Dreamstime.com
Diagram B. Loss of digits in a baby.
In this example, there is an almost total merging of stumpy fingers on swollen arms caused by exposure to radioactive depleted-uranium weapons in the Western Gulf War. Photo by courtesy of Dr S. Horst-Gunther, International Yellow Cross. The two fingers, positioning the baby’s hands for the photograph, are those of the aid worker.
Diagram C. When master switches go wrong.
Experiments on fruit flies (Drosophila melanogaster) demonstrate what can happen when master switches go haywire after irradiation with X-rays or treatment with mutagenic chemicals - chemicals that damage DNA.
The illustrations show experimentally X-ray-mutated fruit flies with displaced organs. Would you be really prepared to believe that positional regulation by master switch genes could occur by random chance by godless and senseless evolution? Master switches determine where our organs are placed and the general appearance of our bodies. Mutations do not lead to an evolved and superior life form but rather damage the original design of living cells, animals and people.
Imagine the perfect biological specimens Adam and Eve would have been before their DNA was damaged over time, shortcomings and disfigurements that gradually become evident in their descendants.
Do you remember what I discussed about metamorphosis in the butterfly? Although most of the body is digested to liquid and pulp in the pupa the imaginal discs that house the master switches don’t. They remain intact and are ready to be expressed for the precise construction of uniquely new legs, wings and head forming the entire adult butterfly, complete with sex organs, which the caterpillar did not possess, using the rich soup of minerals and amino acids from the pupa stage as raw material.