Assignment: Gene-environment interaction
Assignment: Gene-environment interaction
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Gene-environment interaction is a critical process in understanding development. Genes cannot work alone, as they are programmed to respond to signals in the environment. Two basic concepts allow us to understand how genetics influence development.
Firstly, a gene usually has two alleles or alternate forms that carry a trait such as eye color – one from the mother and one from the father. Secondly, the alleles can be the same from both parents or different. For example, blue eye alleles may be inherited from mother and father, or blue eye alleles can be inherited from the mother while brown eye alleles are inherited from the father. If the alleles from both parents are the same, the person is homozygous for that trait. If the alleles are different, the person is heterozygous.
Let’s say the mother is Aa and the father isAa . As you can see in the table, the three possible combinations of alleles received by the child are:
1. AA
2. aa
3. Aa (which is the same as aA)
The first two combinations are homozygous. A person with two alleles for blue eyes will have blue eyes. The third combination is heterozygous. If a trait is heterozygous, the traits may:
BLEND
COMBINE BUT NOT BLEND
DOMINANCE
SEX-LINKED GENES
GENE INTERACTION
DEVELOPMENTAL DISORDERS
DOWN’S SYNDROME
Genetic Engineering
Advances in genetics have pros and cons. Genetic counseling enables couples to be tested for defective genes, and to undergo assisted reproductive techniques in which defective eggs or sperm are substituted for healthy donor ones. It is also possible to detect abnormalities by sampling cells from a fetus. This testing gives the parents the option to abort abnormal fetuses.
This raises ethical issues around determining when defects are serious enough to warrant abortions. What will the child’s quality of life be? Will they be able to lead relatively pain-free, productive lives? Is a painful death expected in a few years or months?
Gene therapy may allow us to cure and ameliorate defective genes in the future. So far, scientists have had limited success in treating deadly disorders. One treatment uses viruses that have had their harmful properties removed to carry healthy genes into patients’ cells. Few treatments have been successful, and it will still take time to perfect gene therapy.
This blind girl benefited from a supportive environment
