Physical Traits

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23rdMarch 2017



Colorblindness is a hereditary condition which is passed from parents totheir kids. People affected by this disorder do not see or recognizecertain colors. The red-green color vision defects are passed on fromthe female parent to the son (InheritedColour Vision Deficiency,2015). Color blindness is a sex-linked disorder meaning that it isfound on the sex chromosome. Its gene is found on the twenty-thirdchromosome which is the sex chromosome. Chromosomes are structureswhich contain genes which in turn contain directives or instructionsabout the development of tissues, organs or cells. If the developmentof a person’s cone cells is defective or the cells sensitivity islow or they are completely missing, then they become color blind.Color blindness can also occur if the pathway from your cone cells tothe brain is not completely developed.

Patternof Heredity

Thered/green color blindness is inherited in an X-linkedrecessive pattern.There are specific genes located on the X-chromosome which isresponsible for this defect. These genes are the Opsin 1, long wavesensitive and the Opsin 1, medium wave sensitive (Inherited ColourVision Deficiency, 2015). Males have only one X-chromosome whilefemales have two X chromosomes. Therefore, males are more susceptibleto colorblindness than females. This disorder can only be inheritedfrom mothers to their sons. Fathers cannot pass on the defect.

Roleof DNA in Causing Red/Green Color Blindness

Theopsin 1 genes, both long wave sensitive and medium wave sensitive,are responsible for producing proteins sensitive to red and greenlight waves. Mutations in these genes cause the red-green colorvision defects.

DNAis passed from parents to their children. Gametes, both male andfemale, are formed during meiosis which is cellular reproductiondaughter cells. The new cells contain half the number of cells astheir mother cell. During meiosis, DNA is copied and divided into twocells which later split to form four cells containing half number ofchromosomes. The daughter cells mature into gametes. The male andfemale gametes (haploid) fuse to form a diploid cell. The ova maturein the ovaries while sperms mature in testes.

Replicationis the process of producing new copies of DNA from its strands.During replication, the double helix strands are separated and usedseparately as a template. This process is called semi-conservativereplication(InheritedColour Vision Deficiency,2015). In cells, this process begins at specific regions known asorigins of replication. The process of replication occurs in threemain steps: initiation, elongation, and termination.

Thehuman DNA contains different genes. These genes are the onesresponsible for specific functions or traits in the body. To expressthese traits, the genes are converted to protein. The proteins areresponsible for the different traits. All traits cannot be the samebecause specific genes are synthesized to produce specific proteins.The base pair patterns in the DNA encode the instructions whichproduce proteins responsible for the traits. DNA as a moleculecontains instructions that a cell requires to continue its functionas well as survival. The information is found in form of genes. Theseinstructions are encoded through the process of transcription andtranslation. Transcription is a process by which DNA molecule isconverted into RNA, which is then converted into proteins. Theseproteins are the basis of gene expression where they give traits viathem.

Roughly,a child receives half the amount of genetic material from eachparent. It depends on whether the child is male or female because theX-chromosome is larger than the Y chromosome and a female has twoX-chromosomes from both parents while a male child has anX-chromosome from the mother and Y-chromosome from the father.Therefore, the female will tend to portray equal characteristics fromboth parents but the males inherit lesser from the father. There aresome carried traits that do not express in some cases. These traitsexhibit an incomplete dominance. If a parent is a carrier of such agene, then it might be passed to the child and expressed even thoughthe parents do not have the trait.

Someenvironmental factors may cause epigenetic changes. Such factors astoxins, drugs, or foods might alter the structure of proteinssurrounding DNA surrounds or the way compounds bind to it. Thestructural changes might cause DNA mutations. Some of these mutationsinclude deletion, substitution or insertion. Deletion is a process bywhich a segment of DNA is completely removed from the sequence.Insertion occurs when extra base pairs are added to the DNA sequencewhile substitution occurs when one base is put in place of another.Cell mutations might cause cancer which can be hereditary. If amutation in a parent cell leads to cancer, then this can be passed onto their children.


InheritedColour Vision Deficiency. (2015). Retrieved March 23, 2017, from