Chromosomes, are a special type of protein called a "Nucleic Acid."
They are located in the nucleus of a cell, and provide the code to make
protein which will build, repair, or reproduce any
cell within a living organism. In humans there are 23 pairs
of chromosomes, or 46 single chromosomes in all cells of
the body except the sex cells.
Autosomes are regular body cells, reproduce using
Mitosis, or asexual reproduction. 1 cell becomes 2 new cells.
Gamete cells the sex cells reproduce using Meiosis or sexual
reproduction. 1 cell becomes 4 new cells. What does a Chromosome look
like? What does a Chromosome Pair look like?
Genes are the smallest chemical parts that form segments of chromosomes.
Genes determine what we look like. There are not two organisms alike in
the world unless you are an identical twin or a clone.
Alleles are an alternate form of a gene for one trait.
E.g. Brown and blue eyes are two different alleles for eye color. We have
2 alleles for any, one trait, one from our mother and one from our father.
They may be the same form of the gene or two different forms.
Genotype is the actual code that these alleles or
genes possess (E.g. Tt or TT or tt). The gene may or may not be expressed
when you observe a living organism.
Phenotype is the expressed appearance of a living
organism. (E.g. Brown eyes, green eyes, freckles). The Phenotype expression
will be due to genes that are dominant or overpower the other alleles
that are not expressed.
Recessive alleles not expressed in the phenotype.
Dominant, the expressed allele in the phenotype.
Recessive gene traits:
You may carry the recessive gene for being an Albino, but because you
also have the dominant gene for pigmentation (colored) all of your
body cells are colored.
Other examples of alleles you may have that you don't express (recessive)
are: non-tongue rolling, shortfingeredness, atavism (extreme hair growth),
"sickle shaped" red blood cell (poor oxygen carrier - but fights malaria
caused by Plasmodium larva from mosquito), and lack of dimples (dimples
are dominant). Why would it be an advantage to have "Sickle cell" anemia
if you lived in the tropics? Could this also be a disadvantage?
Dominant gene traits:
The opposite or dominant alleles that you most likely possess to these
traits are tongue rolling, normal finger length, normal Red Blood Shape.
Some rather sad cases of dominant alleles, that fortunately few people
have had historically are: Huntington's Chorea (causes uncontrollable
twisting of face and limbs--about age 40) which has been traced to 3 Dutch
immigrants that came to Salem, Massachusetts (1650). Their dominant alleles
sadly led to the Salem Witch Trials.
Marfans Syndrome which causes weakened ligaments/connective tissue,
and can lead to heart failure as with Flow Hyman, and Pistil Pete Merevich
("NBA" player). Abraham Lincoln is suspected to have had this disease.
Use your computer to research more on Marfan's Syndrome, Huntington's
Chorea.
Can behavior be passed on genetically?
Are there genetic diseases you could pass on to your offspring?
Describe how genetics can be used to identify a person who is dead?
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