Exploring Heredity Traits Essay, Research Paper
Exploring Hereditary Traits
My experiences working on this experiment haven t been easy as it could have been. I realized that waiting until the last minute and not following the assigned dates landed me in a stressed position that could have been prevented. Now I have more work than I had to begin with.
My hypothesis is to determine the possible genotypes for some inherited traits. The dependent variables are the phenotypes and possible genotypes and phenotype; the independent variables are the traits. The subject is genetics and heredity traits. I didn t really do any treatments on the subject I just researched it and made six replicates of the chart.
Heredity is the transmission of biological traits from one generation to the next. Heredity is within the nucleus of the cell in structures called chromosomes. The chromosomes carry smaller units called genes that contain the heredity code. Every living thing reproduces its own kind or species and most of them have a genetic makeup of some sort.
Even before the beginnings of written history people were aware of some of the ways in which heredity takes place. Domestic animals and plants of today are proof of this. Today’s domesticated horses, cattle, dogs, corn, wheat, and cotton differ greatly from their primitive, wild ancestors. They are products of the ancient breeders’ art, an art that included the proper selection of parents, well-controlled matings, and the careful choice of the best offspring to further improve a breed.
In 1859 the English biologist Charles Darwin published his epic ‘The Origin of Species’, an attempt to demonstrate that all living things are related through the common bond of evolution (see Evolution). Darwin assumed that all species produce more offspring than reach maturity. Those offspring that survive and reproduce, he reasoned, do so because they are better suited to the existing environment. Because environment changes with time, he argued, species must either adapt to the new conditions or become extinct. Darwin did not know just what mechanisms made it possible for such changes in species to take place. He recognized, however, that if his theory were correct, changeable–or mutable–units of heredity must exist and that variations in species must arise as a result of an accumulation of small changes in these units of heredity. In 1865 Gregor Mendel, a monk in an Austrian Roman Catholic monastery, wrote a paper that laid the foundation for modern genetics. Mendel was the first to demonstrate experimentally the manner in which specific traits are passed on from one generation to the next. He concluded that “discrete hereditary elements” (not called genes until the 1900s) in the sex cells are responsible for the transmission of traits. Mendel was ahead of his time, however. The significance of his work was not realized until 1900. In the monastery garden where he conducted his experiments, Mendel observed the inheritance of traits in the easily available garden pea. The plant is an ideal genetic working material because a number of progeny can be produced in a short time and because its reproductive parts are so constructed that accidental fertilization is nearly impossible.
Mendel began by tracing the inheritance of one or two contrasting traits at a time. He crossed tall peas with short peas or red-flowered peas with white-flowered peas. Then he would record how many of the progeny developed each of the contrasting traits. He used the progeny in subsequent matings to follow the progress of the traits under study through a number of generations.
1. Make a table with 3 columns and 9 rows. Head the columns Trait, Phenotype, and Possible Genotypes. Down the first columns list the nine traits shown below.
2. In the second column of the table you will write yes or no depending on whether you possess each trait. For the traits you can t observe directly work with a partner. Each trait is a dominant allele.
h Tongue rolling (R): Stick out your tongue and try to to roll up the sides so that the tongue forms a U-shape.
h Free Earlobe (F): The lobe of the ear hangs freely below the point of atachment to the head.
h Widow s Peak (W):The midpoint of the hairline along the front of the forehead points down.
h Straight Thumb (N): When extended from the palm of the hand, the top segment of the thumb forms a straight line with the bottom segment.
h Straight Little Finger (S): The last segment of the little finger forms a straight line with the rest of the finger rather than bending toward the ring finger.
h Left-over-right thumb crossing (L): When the hands are folded in a natural fashion,the left thumb crosses over the right.
h Chin Cleft (c): The center of the chin has an indentation resembling a deep dimple.
h Mid-digital Hair (H): Hair is present on the middle section of your fingers.
h Six fingers (B): Six fingers are present on either hand (or were present at birth).
Traits Phenotypes Possible Genotypes
Tongue rolling (R) Yes RR
Free Earlobe (F) No Ff
Widow s Peak (W) No Ww
Straight Thumb (N) Yes NN
Straight little finger
(S) Yes SS
Left-over-right thumb crossing (L) Yes LL
Chin cleft (C) No Cc
Mid-digital Hair (H) Yes HH
Six fingers (B) No Bb