top-rated free essay

Mendelian Genetics

By vinnho Jun 21, 2013 838 Words


Gregor Mendel, who is now considered as founder of classical genetics, ( Elrod S. & Stansfield w,2010), conducted a series of experiments using garden pea plants, his aim was to find a way of explaining to his fellow scientists who believed the blending theory which had been proposed earlier by Wiseman, that heredity involved the interaction of discrete separable factors (now known as genes) After a statistical analysis of the results of his experiment, Mendel came up with two Laws of Genetics, The first law called the law of segregation which states that there are pairs of particulate factors which control each trait and they segregate during gamete formation and then come together randomly at fertilization. The second Law, the law of independent assortment states that the inheritance of a certain gene is not affected by another gene on another chromosome. This current experiment is a replica of Mendel’s and it will show how his ideas still apply to nowadays phenomena. 1.2 OBJECTIVES:

The objectives of the experiment are:
To demonstrate how genes interact with each other to produce different appearances (phenotypes) •To relate Mendel’s laws of genetics to our current experiment using, red and striped beans respectively. •To apply statistics to our biological experiment i.e. using Chi-Square Technique

2.0 Materials and Methods
Two containers each had an equal number of red or striped beans were provided on the bench in the laboratory. Each container represented a parent and gametes were formed from these parents. Forty beans were selected randomly from each of the parent container (10 beans remained in each container) and the beans were placed in corresponded spaces on the bench. These spaces represented gametes. The number of beans of each color taken from each container was recorded. Without looking, one bean at a time from each of the gamete spaces were taken and paired into the zygote space until all the beans were paired. The genotypes in the zygote space were counted and the number of each genotype was recorded. (Red was dominant over Stripped)


3.1 Table: Showing the number of red and stripped beans from each container PHENOTYPECONTAINER ACONTAINER B

3.2 Table: Showing the number of beans of different phenotypes after paired at the group. GROUPREDMIXEDSTRIPPED

Phenotypical ratiogenotypical ratio
9+22=31 (red beans): 9 = (stripped beans) 9 (red beans): 22(mixed beans):9(stripped beans) 31:99:22:9
(Since in the experiment red was dominant over stripped, then the combination of red and stripped ended up having a red phenotype.)

3.3 Table: Class Cumulative Data after paired
Total CCD166327147

Total CCD of Red, mixed and stripped=166+324+147
Phenotype RatioGenotype ratio
Red+ mixed: StrippedRed: mixed: Stripped
490:147 1.12:2.20:1

3.4 Table: showing the genotypes of beans in punnet square according to Mendelian Monohybrid ratio R = Red
r =Stripped
Gametes Rr

F2 3 Red: 1 Stripped
3: 1 (Mendelian Monohybrid ratio)

3.5 Table: Showing the Chi Square Calculation of Class Cumulative Data χ2= ∑(O -E)2/E
Expected results : Red 3/4×640 = 480
: Stripped 1/4×640= 160

∑= χ2=1.2645

Degree of freedom = number of Classes – 1
The probability value on the Chi Square test distribution results was =0.20≈ (30%) 4.0 DISCUSSION
On the chi-square test distribution results showed that there was a probability amounting to about 30% that the diffrection of the observed results was due to chance alone. However in real biological scenario the combination of genes alone cannot determine the appearance (phenotype) of the offspring but the environment in which the combination happens also contribute to the phenotype of the offspring.

Elrod and Stansfied (2010) mention that, if the p value is greater than 0.05, the results are accepted and if the p value calculated on the Chi-Square is less than 0.05, the hypothesis is rejected. Since p> 0.05, and also the results from class cumulative data phenotype ratio was 3.33:1 close to the expected results of Mendelian phenotype ratio of 3:1. Then the hypothesis is accepted.

Elrod S. & Stansfield w. (2010): Schaums outlines- Genetics ( 5th edition) p.41. Mc Graw . New York

6.0 Bibliography
Hartl, D.L. & Jones, E.W (1998) Genetics principles & analyzing (4th edition), Jones and Bartlett Publishers, Toronto, Canada. Brooker R.J (2009): Genetics analysis & Principles (3rd edition) P.23 Mc Graw. New York.  

Cite This Document

Related Documents

  • Mendelian Genetics

    ...Mendelian Genetics Introduction In 1865 an Austrian monk, Gregor Mendel, presented the results of painstaking experiments on the inheritance of the garden pea. Those results were heard, but not understood, by Mendel's audience. In 1866, Mendel published his results in an obscure German journal. The result of this was that Mendel's work was ign...

    Read More
  • Mendelian Genetics Lab Report

    ... Lab Report: Mendelian Genetics Introduction: In 1866 an Austrian monk, Gregor Mendel, presented the results of painstaking experiments on the inheritance patterns of garden peas. Those results were heard, but probably not understood, by Mendel’s audience. Now, more than a century later, Mendel’s work seems elementary to modern–day ge...

    Read More
  • Mendelian Genetics

    ...Mendelian Genetics * Pea plants have several advantages for genetics. * Pea plants are available in many varieties with distinct heritable features (characters) with different variants (traits). * Another advantage of peas is that Mendel had strict control over which plants mated with which. * Each pea plant has male ...

    Read More
  • Timeline of Genetics

    ...champions the study of heredity in England. 1902 A human disease is first attributed to genetic causes ("inborn errors of metabolism"). (Sir Archibald Garrod, alkaptonuria) 1902 The chromosome theory of heredity is proposed by Sutton. Boveri recognizes that individual chromosomes are different from one another, but he doesn't make a connecti...

    Read More
  • The Beginnings of Modern Genetics

    ...GENETIC ENGINEERING: THE BEGINNINGS OF MODERN GENETICS The first scientific investigation of inheritance came from an unlikely place—a monastery garden in what later became Czechoslovakia. There in the 19th century, a monk named Gregor Mendel bred generations of pea plants, observed the way they inherited characteristics, and founded moder...

    Read More
  • Mendelian Genetics, Scientific Paper

    ...Law”: Observing Anthocyanin in Brassica rapa Abstract The foundation of genetics lies with the principles that Gregor Mendel outlined after his experiments with pea plants where he discovered the relationship between physical characteristics, or phenotype, and genetic traits, or genotype. This experiment aimed to reproduce Mendel’s res...

    Read More
  • Mendelian Inheritance in Drosophila

    ...Lab#3 Mendelian Inheritance in Drosophila Lab Report 1 In this experiment we are investigating the strength of the ratios discovered by Gregor Mendel in both the monohybrid and dihybrid cross. The ability to test these ratios stems from the use of Mendel’s law of segregation which states that during meiosis allele pairs will separate...

    Read More
  • Genetic Observations Through the Studies of Hybrid Corn, Single Gene

    ...Genetic Observations Through The Studies of Hybrid Corn, Single Gene Human Traits, and Fruit Flies The basic foundation of modern genetics was led by Gregor Mendel (Corcos, 1993). Mendel was not the first to experiment with heredity, and our Lyman Briggs biology class will not be the last to deal with genetics. Genetics is the science of he...

    Read More

Discover the Best Free Essays on StudyMode

Conquer writer's block once and for all.

High Quality Essays

Our library contains thousands of carefully selected free research papers and essays.

Popular Topics

No matter the topic you're researching, chances are we have it covered.