Lesson Explainer: The Human Genome Project Biology

In this explainer, we will learn how to discuss the aims and implications of the Human Genome Project.

Our genes provide a blueprint for what we look like and some aspects of how we act and how our bodies function. Though our environment also impacts the majority of our features, scientists are still trying to better understand the role of our genes. Understanding the function of our genes can be helpful not only to predict the development of genetic diseases, but also to determine how someone reacts to certain medicines because of their genetics.

Genes are sections of a DNA molecule that contains the information to produce a functional unit such as a protein. These molecules determine what our cells look like and the functions they carry out.

Definition: Gene

A gene is a section of DNA that contains the information needed to produce a functional unit (e.g., a protein).

Following the discovery of DNA as the genetic material of all living organisms, scientists have become increasingly curious about the location and function of the different genes organisms possess. A person’s genome is all the genes and noncoding regions of DNA they have and the sequence of nucleotide base pairs that they consist of.

Definition: Genome

The genome is all the genetic material of an organism.

Some of the functions and locations of genes in the human genome have been revealed gradually throughout the 1900s. By the mid-1980s, 1‎ ‎500 genes on the human genome had been identified including a gene that triggers an increased blood cholesterol that is a major risk factor in developing heart disease, and some genes that can make a person more at risk to develop certain cancers.

The Human Genome Project was a huge research project that aimed to understand the position and function of every single human gene. It was an international project, involving collaboration between many different countries, so that the knowledge they gained could be shared by scientists all over the world to analyze the functions of these genes. The human genome consists of around 30‎ ‎000 genes, so we can see just how ambitious this project was!

In the year 2000, the president of the United States of America, Bill Clinton, said about the Human Genome Project, “Without a doubt, this is the most important, most wondrous map ever produced by humankind.”

The main objective of the Human Genome Project was to fully map the human genome so scientists would know where each gene is located and the order of nucleotide bases in each gene (a process called sequencing). They succeeded in this aim in 2003, and now scientists are able to read the complete instructions that our cells follow to build a human being.

Example 1: Describing the Aims of the Human Genome Project

Which of the following was not a basic aim of the Human Genome Project?

  1. To determine the order of the base pairs in the human genome
  2. To identify all the genes in the human genome
  3. To sequence and share DNA with people investigating crimes
  4. To develop faster methods for sequencing DNA

Answer

The Human Genome Project was an international initiative to map the entire human genome. This meant that the order of all the nucleotide base pairs, and the genes they made up, in the human genome was identified. We can see that the options describing determining the order of the base pairs in the human genome and identifying all the genes in the human genome are therefore correct, so they cannot be our answer.

Mapping the genome allows scientists to determine the location of genes and how they might function. This is particularly important for analyzing whether someone might develop a genetic disease, especially those that develop later in life.

The collaborative nature of the Human Genome Project, sharing information internationally around the globe, was an opportunity for all countries and people to benefit from the information it provides. By allowing scientists worldwide to analyze, store, and share the genetic information gained by studying the human genome, the Human Genome Project achieved its collaborative goals. This also permitted scientists to work collaboratively to improve worldwide genetic sequencing techniques, which means that DNA can now be sequenced far faster than before the project was introduced.

The human genome project did not, however, aim to sequence DNA to share this information with people investigating crimes. The main aim was to find the location of all the genes in the human genome, determine the order of bases, and develop faster sequencing methods, not to link specific people to certain crimes.

Therefore, the option that is not one of the main aims of the Human Genome Project is to sequence and share DNA with people investigating crimes.

Figure 1 below displays a representation of the human genome in red, showing all 23 pairs of chromosomes in the nucleus of a typical human cell. A homologous chromosome pair is a pair of chromosomes that are similar lengths and have the same genes at the same location. Genes are heritable, meaning that they are passed down from parents to their offspring.

On each of the 23 paired homologous chromosomes in each body cell, each chromosome in the pair has a version of the same gene. One of the chromosomes in the pair has been inherited from a person’s biological mother and the other from their biological father. Different versions of genes are called alleles.

An example of this can be seen in Figure 1. A region on chromosome 15 contains one of the two major genes involved in determining someone’s eye color. You have two copies of chromosome 15 in each of your body cells, one inherited from your biological father and one from your biological mother.

The gene that controls eye color will be found in the same position on the chromosome you inherit from your father and the chromosome you inherit from your mother. However, you may inherit different versions of the gene from each parent. The allele for blue eyes may have been inherited from your mother, and you may have inherited the allele that produces green eyes from your father. These alleles are different versions of the same gene. The different alleles of a gene make up the individual’s genotype for that gene.

Definition: Allele

An allele is an alternative version of a gene.

Let’s have a quick look at some examples of genes that have been mapped by the human genome project.

The genes that determine the general pattern of a person’s fingerprint, for example, were found to be located on chromosome 8. The genes that determine a person’s blood group were found on chromosome 9. The gene for forming two important proteins, a hormone called insulin that helps control our blood sugar level and a globular protein called hemoglobin that allows our red blood cells to carry oxygen, were both found to be located on chromosome 11. Some genes were also found to be sex linked, which means that they are carried by the sex chromosomes. For example, the genes that cause color blindness and hemophilia are both located on the X chromosome.

A key example of why it is useful to understand more about the human genome is predicting the likelihood of developing a genetic disease, such as hemophilia.

Another example of a genetic disease is Huntington’s disease. Huntington’s disease impairs a person’s ability to move, negatively affects their memory and cognition, and can impact their control of their emotions. The signs of Huntington’s disease will usually not appear in a person until they are over 30 years old. This means that people can grow up and have children, passing on the gene that codes for Huntington’s disease to them, before the parents even know they have inherited this disease themselves.

Huntington’s disease is caused by a dominant allele, which means a person only needs to have one copy of the allele present in their genotype to be affected by it. By knowing which gene will be affected, genetic screening can be carried out to determine if you might develop it, as Huntington’s is likely to develop later in life. The Human Genome Project aimed to make genetic conditions like these easier to predict.

The Human Genome Project’s sequencing of the genome is also incredibly useful for understanding how different alleles react to medicines to make treatment more effective and targeted. This can help to improve someone’s quality of life who is living with the genetic disorder, as they will be able to receive the optimal treatment and will know about any lifestyle changes they need to implement early enough to possibly slow the development of the disease. Knowing someone’s genome also means that any negative effects of treatment can be predicted and hopefully avoided.

Example 2: Describing the Benefits of the Human Genome Project for Disease Prediction

Huntington’s disease is a neurodegenerative disease where symptoms usually become apparent at 30–50 years of age. Why might someone whose parent has just been diagnosed with Huntington’s disease want their genome sequenced?

  1. To alter their DNA sequence and prevent themselves from inheriting the disease
  2. To determine at exactly what age they will experience symptoms
  3. To predict their life expectancy and that of their children
  4. To determine if they will also inherit the disease and prepare for it

Answer

The Human Genome Project was an international initiative to map the entire human genome. This meant that the order of all the nucleotide bases, and the genes they made up, in the human genome was identified. This allows scientists to determine the location of genes and how they might function. This is particularly important for analyzing whether someone might develop a genetic disease, especially diseases that develop later in life. By understanding more about how a person’s genetics may make them more prone to developing certain conditions and how their alleles interact with specific medicines, more effective and safe treatments can be developed to combat diseases.

Huntington’s disease impairs a person’s ability to move, negatively affects their memory and cognition, and can impact their control of their emotions. The first signs of Huntington’s disease will usually not appear in a person until they are over 30 years old. This means that people can grow up and have children before they even know they have inherited this disease. Huntington’s disease is caused by a dominant allele, which means a person only has to have one copy of the allele present in their genotype to be affected by this disease. Knowing about the risk you have of developing a genetic disease like Huntington’s, which is passed from parent to offspring, also gives more time to implement lifestyle changes that might help lessen the risk. It can be helpful in mentally and physically preparing a person who is likely to develop the disease.

Therefore, the benefits of mapping the genome of someone who has a family history of Huntington’s disease is to determine if they will also inherit the disease and prepare for it.

There are, however, drawbacks to these applications of the human genome project. It might not improve someone’s quality of life if they knew they were likely to develop a terminal or degenerative disease in a matter of years. Informed consent of those undertaking any genetic screening is therefore essential so that it is the choice of the individual undergoing genetic screening to find out potentially life-changing information. There is clearly much debate about the ethical aspects of knowing whether you are prone to genetic diseases.

Another negative implication that may arise from the Human Genome Project is the concern surrounding storing and sharing personal data. Mapping someone’s genome is the most personal information you can possess about them, and as new genes are identified, particularly those for disease, knowing someone’s genome may make it easier to discriminate against certain groups of people. Efforts were made by the Human Genome Project to source anonymous volunteers for the project to prevent this outcome.

Aside from the clear accomplishments of the Human Genome Project in identifying many human genes, including those related to genetic diseases, it has also leaped forward DNA sequencing techniques. DNA sequencing is a technique that identifies and sorts all DNA bases in a genome into order. The Human Genome Project has sped up this DNA sequencing technique, so now a whole single human’s genome can be sequenced in about a single day—though its analysis will take longer!

Key Term: Sequencing

DNA sequencing is the process of determining the order of nucleic acid bases in DNA.

The improvement in DNA sequencing techniques presents another benefit of the Human Genome Project, this time an economic one. The project was projected to cost around $3 billion and ended up costing only $2.7 billion. Now, thanks to the efforts of the Human Genome Project in improving sequencing techniques, the cost to sequence a human genome is much, much cheaper.

Example 3: Describing the Benefits of the Human Genome Project

Fill in the blank: One of the benefits of the Human Genome Project is the identification of genes.

  1. noncoding
  2. disease-causing
  3. mobile
  4. recessive

Answer

The Human Genome Project was an international initiative to map the entire human genome. This meant that the order of all the nucleotide bases, and the genes they made up, in the human genome was identified. This allows scientists to determine the location of genes and how they might function.

This is particularly important for analyzing whether someone might develop a genetic disease, especially those that develop later in life. By identifying disease-causing genes, the people who possess these genes and are therefore more prone to developing certain conditions can also be identified.

Very few human characteristics rely solely on their genetic makeup, with genetic diseases being one of the few that seem to be more influenced by genes than environment. Analyzing the development and treatment genetic diseases are the primary ways the Human Genome Project benefits research and medicine.

Therefore, one of the main benefits of the Human Genome Project is the identification of disease-causing genes.

Table 1 summarizes some of the main benefits that resulted from the Human Genome Project and highlights some of the possible negative implications.

Let’s recap some of the key points we have covered in this explainer.

Key Points

  • The Human Genome Project succeeded in its aim to map the location of every human gene and share this information internationally for collaborative research into genetics.
  • This is helpful for identifying people at risk of developing genetic diseases and prescribing appropriate, effective medicines.
  • Negative implications of the Human Genome Project include concerns around personal data sharing and the negative impact knowledge of a risk to develop degenerative disease may have on someone’s quality of life.

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