Are the genes of siblings
related? Understanding the genetic structure of siblings presents a challenge,
as is comprehending your own genetic structure.
“Do my sister and I have the
same genes? How can this be possible if the color of our eyes is different? We
do look alike in some other ways.”
In this particular instance, a
young man wants to know if his genetic structure is identical to or different
from that of his sister because other than the color of their eyes, their
photographs reveal other, distinct similarities in appearance.
A basic explanation of genes,
genotypes, gene structure and genetic mapping will help to answer his questions and
some of yours.
What are genes?
MedlinePlus offers some basic information about
genes.
“A gene is a short piece of DNA, which tells
the body how to build a specific protein. There are approximately 30,000 genes
in each cell of the human body. The combination of all genes makes up the
blueprint for the human body and its functions.”
What is a genotype?
“A person's genetic makeup is
called a genotype.”
Discussing genetic
structure further may help to
answer more questions.
“Genes are located on strands
of DNA, just like beads on a string. The DNA strands make up the chromosomes.
Chromosomes contain matching pairs of one copy of a specific gene. The gene
occurs in the same position on each chromosome.”
Chromosomes,
like sex chromosomes that determine gender, come from the parents of siblings.
For example,
“In females, one sex chromosome
gets its gene from the mother; the other matching sex chromosome has the gene
from the father. In males, a single X chromosome comes from the mother and a
non-matching Y chromosome comes from the father.”
Genes control traits that are evident in siblings, for
example, their eye color.
“Dominant
traits are controlled by one
gene in the pair. Recessive
traits require both genes in
the pair to work together to control the trait.”
Thus, in siblings, including
yours, there may be similarities or differences in eye color, but these traits
are not inherited from each other or transferred in any way from one to the
other. One sibling can inherit blue eyes, which is a dominant trait and the
other brown eyes, as a recessive trait. For example, a male sibling may have
blue eyes similar to those of his mother, while the female sibling has brown
eyes similar to those of her father.
Note that genetic structure
does not just involve the parents of siblings, as there are grandparents,
great-grandparents, etc. many generations back, to consider. Like the
siblings, each parent or grandparent is born with a unique, blue print that has
specific, unique traits that siblings can inherit from their parents. Siblings
do not necessarily inherit the same trait.
Gene tracking enables one to follow genetic
similarities and differences in genetic structure from generation to
generation. On the other hand, genome mapping involves creating a genetic map
that designates or assigns DNA to a specific chromosome. This is currently
proving to be useful in terms of ongoing medical research.
Genome mapping is a
relatively new science open to further discovery with respect to anyone
seriously interested in finding more answers related to the genetic structure
of siblings or desiring to pursue the study of genetics further.
Siblings born of the same
parents can have a similar genetic structure, but many questions remain
unanswered with respect to the relationship of genetic structure in siblings.
No comments:
Post a Comment