Genes and Mendelian Inheritance Essay Assignments

Genes and Mendelian Inheritance Essay Assignments

Chapter 7

Genes and Inheritance

Learning Objectives

• Explain the concept of a single-gene trait

-Heredity: The passing of characteristics from parent to offspring through their genes

• Describe Mendel’s contributions to the field of genetics Genes and Mendelian Inheritance Essay Assignments

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-Conducted experiments to understand the theory of genetics.

• Be able to define the terms gene, allele, dominant, recessive, homozygous, and heterozygous

Gene- The instruction set

Allele- 2 inherited copies of a gene

Dominant-

Recessive-

Homozygous-

Heterozygus-

• Characterize the difference between an organism’s genotype and its phenotype

Genotype- Genetic Composition of an organism

Phenotype- Physical makeup of an organism

• Describe the difference between an organism’s genotype and its phenotype

-Genotypes can be Homozygus Dominant or Heterozygus

• Demonstrate the ability to perform Punnett squares to predict the offspring of parents with particular genotypes.
• Understand how to use the rules of probability to predict the inheritance of specific traits
• Explain how a test-cross can be used to determine the genotype of an organism
• Predict patterns of inheritance based on pedigree analysis
• Explain how each of the following genetic “rules” works: incomplete dominance, codominance, multiple alleles, polygenic inheritance, and pleitropy

Incomplete dominance- in which the heterozygote appears to be intermediate between the two homozygotes.

Codominance- in which the heterozygote displays characteristics of both homozygotes

Multiple Alleles- in which a single gene has more than two alleles

each individual still carries only two alleles

• Understand how the ABO and Rh markers contribute to human blood type

-The A and B alleles are both completely dominant to O.

-The A and B alleles are codominant to each other.

• Explain how blood type compatibility is determined
• Describe how sex linked traits are inherited
• Understand that phenotypes are a combination of genotypes and the environment
• Explain why linked genes do not assort independently
• Genes and Mendelian Inheritance Essay Assignments

Description

Genetics is the study of genes, genetic expression, and the way in which organisms inherit genetic traits from their parents. Inheritance and Mendelian genetics describe the ways in which organisms receive these traits from their parents. Gregor Johann Mendel is known as the father of modern genetics for his discoveries of the principles of heredity based on his work with pea plants in the 19th century. He described inheritance as a particulate and established two important laws: the law of segregation and the law of independent assortment. Modern genetics expands Mendel’s discoveries; we now know diploid organisms carry two copies of each gene. An individual’s genetic makeup is its genotype, while its expressed traits make up its phenotype. Genes and Mendelian Inheritance Essay Assignments.

At A Glance

• Gregor Mendel, the father of modern genetics, discovered the mechanism of inheritance.
• Mendel used pea plants to learn the genetic basis of inheritance.
• Variants of a gene are called alleles, which can be either dominant or recessive. An organism’s genotype (its genetic makeup) determines its phenotype (its expressed traits).
• Genetic diversity is increased by independent assortment ( independent inheritance of genes) and crossing over during meiosis.
• Genes that lie close to each other on chromosomes tend to be inherited together.
• Genes do not always follow the patterns Mendel observed.
• Incomplete dominance results in a blending of alleles, while codominance results in the expression of both alleles simultaneously.
• Some genes have more than two alleles.
• Pleiotropy happens when one gene codes for more than one phenotype.
• Some traits are the result of multiple genes. Traits can be coded for by more than one gene, known as polygenic inheritance, or one gene can activate another gene, known as epistasis.

Genetics and Inheritance
Genetic inheritance is the greatest contributor to the character and body traits of an offspring. This happens when the chromosomes containing the genes are inherited by an offspring from the parents during reproduction. As a result of this inheritance, any genetic condition from a parent is passed to an offspring, and becomes part and parcel of his body and health in general. Genes and Mendelian Inheritance Essay Assignments. It is important to note that, genetic disorders are an integral part of such an inheritance, and it is, therefore, significant to look at some of the genetic disorders and how they happen in humans.

Information on this study has been obtained from the National Human Genome Institute, and other book sources. Sickle cell disease, cystic fibrosis, thalassemia, and Ta-Sachs disease (‘Genetics,’2015), are some of the unusual genetic conditions that have been identified from these sources. For the purpose of this study, sickle cell disease will be the focus, where the chromosomal theory of inheritance, symptoms, impact on quality of life and longevity, and the relationship between chromosomes and DNA, will be looked at. Genes and Mendelian Inheritance Essay Assignments.

Sickle cell alters the red blood cells, which circulate oxygen around the body. These cells form abnormally, hindering them from performing their normal functions (‘Genetics,’2016). The chromosomal theory of inheritance gives an insight of how chromosomes transmit genetic disorders from a parent to an offspring. For parents with a genetic history of the disease, they contribute a set of chromosomes with elements of the disorder to an offspring during the process of reproduction, when these games meet (Griffiths et al, 1999). As such these abnormalities contribute to a high percentage of the genetic disorder that a family will have in his lifetime.

There exist a very close relationship between the chromosomes and DNA. As seen earlier, the chromosomes carry the genes that are transmitted from a parent to an offspring. In that process, the parent shares all the characteristics and traits including any disorder. The genes, on the other hand, form a necessary component of the DNA that has all the instructions that give the human body characteristics (Griffiths et al, 1999), such as the nose and the size of the feet, among others. The chromosomes, therefore, make a significant contribution to the DNA of a person. Genes and Mendelian Inheritance Essay Assignments.

Sickle cell is a lifetime disease that affects the normal body function, though earlier diagnosis can help contain it. Some of the notable symptoms of the disease include; sickle cell crises that are very painful, severe anemia, tiredness and lack of enough breathing. This is as a result of the red blood cells failure to carry enough oxygen around the body (‘Genetics,’2016). These conditions affect the average quality of life of an individual because people with such conditions need constant medical attention, and they are always using drugs. As such they cannot live a normal life where they can engage in healthy life dealings. Life expectancy is also reduced because the disorder can only be contained up to a certain point where it cannot be included anymore because other body organs get infections, and the patient loses a life. Genes and Mendelian Inheritance Essay Assignments.

As seen in this study, sickle cell is a dangerous genetic disorder, and as such there is a need for frequent screening for early diagnosis so that the disease is contained at early stages. More research should also be done to come up with more ways of carrying the illness and even the cure for the disease Genes and Mendelian Inheritance Essay Assignments.

References

Genetics, Retrieved from: http://www.genome.gov/

Griffiths et al. (1999). Introduction to genetic analysis. New York: W.H. Freeman and Company. Genes and Mendelian Inheritance Essay Assignments.