Question

A human gene called the \(\beta\)-globin gene encodes a polypeptide that functions as a subunit of the protein known as hemoglobin. Hemoglobin is found within red blood cells; it carries oxygen. In human populations, the \(\beta\)-globin gene can be found as the common allele called the \(\mathrm{Hb}\) allele, and it can also be found as the \(\mathrm{Hb}^{5}\) allele. Individuals who have two copies of the \(\mathrm{Hb}\) allele have the disease called sickle cell disease. Are the following examples descriptions of genetics at the molecular, cellular, organism, or population level? A. The \(H b^{S}\) allele encodes a polypeptide that functions slightly differently from the polypeptide encoded by the \(H b^{\wedge}\) allele. B. If an individual has two copies of the \(\mathrm{Hb}^{5}\) allele, that person's red blood cells take on a sickle shape. C. Individuals who have two copies of the \(H b^{A}\) allele do not have sickle cell disease, but they are not resistant to malaria. People who have one \(H b^{A}\) allele and one \(H b^{S}\) allele do not have sickle cell disease, and they are resistant to malaria. People who have two copies of the \(\mathrm{Hb}^{5}\) allele have sickle cell disease, and this disease may significantly shorten their lives. D. Individuals with sickle cell disease have anemia because their red blood cells are easily destroyed by the body.

Short answer

The level of genetics for each description is A: Molecular, B: Cellular, C: Organism, D: Population.

Step-by-step solution

Analyse the Description A

Looking at description A: 'The \(Hb^{S}\) allele encodes a polypeptide that functions slightly differently from the polypeptide encoded by the \(Hb\) allele.' It discusses the different functions of polypeptides encoded by different alleles. This is a characteristic of the molecular level of genetics, where the study is focused on the genes and their sequences.

Analyse the Description B

Looking at description B: 'If an individual has two copies of the \(\mathrm{Hb}^{5}\) allele, that person's red blood cells take on a sickle shape.' This description concerns a physiological change in the cell caused by a genetic condition, which is an aspect of cellular genetics.

Analyse the Description C

Looking at description C: 'Individuals who have two copies of the \(Hb^{A}\) allele do not have sickle cell disease, but they are not resistant to malaria. People who have one \(Hb^{A}\) allele and one \(Hb^{S}\) allele do not have sickle cell disease, and they are resistant to malaria. People who have two copies of the \(\mathrm{Hb}^{5}\) allele have sickle cell disease, and this disease may significantly shorten their lives.' This scenario illustrates the effect of genetic variations on the entire organism's traits and diseases, so this comes under organism genetics.

Analyse the Description D

Looking at description D: 'Individuals with sickle cell disease have anemia because their red blood cells are easily destroyed by the body.' The given description is referring to a specific health condition prevalent in a section of the population which is directly related to a genetic defect. Therefore, this describes genetics on a population level.

Key concepts

Molecular Genetics

In molecular genetics, we focus on the structure and function of genes at a molecular level. This involves studying DNA sequences and how they encode proteins, which are crucial for various biological functions.

In the exercise, the discussion about how the \(Hb^S\) allele encodes a polypeptide differently than the \(Hb\) allele is a classic example of molecular genetics. Here, genetic variation leads to differences in protein structure, impacting how they perform their functions.

• Genes are made up of DNA sequences.
• These sequences are transcribed and translated into proteins.
• Changing just one nucleotide in a sequence can lead to a different protein being produced.

This level of genetics helps us understand the fundamental building blocks of life and how variations at this level can affect an organism’s health and functioning.

Cellular Genetics

Cellular genetics examines how genetic material influences cellular functions and structures. It's about understanding the role of genetics in cell behavior.

In the given exercise, the explanation that having two copies of the \(\mathrm{Hb}^5\) allele causes red blood cells to take on a sickle shape is a matter of cellular genetics. This genetic alteration directly affects the cell’s morphology and function.

• Genes direct the production of proteins that determine cell structure.
• Abnormal protein function can lead to disease at a cellular level, like sickle-shaped cells that struggle to move through vascular pathways.

By studying cellular genetics, we can comprehend how defects at the genetic level can lead to cellular dysfunctions, providing insights into potential treatment avenues.

Organismal Genetics

Organismal genetics focuses on how genetic variations present in a whole organism affect its traits and health conditions. This ties genetic make-up to physical characteristics.

The exercise description related to malaria resistance and sickle cell disease across different genotypes illustrates organismal genetics. Different combinations of alleles produce varying traits, impacting the overall health and abilities of the individual.

• Homozygous \(Hb^A\) individuals do not show sickle cell traits.
• Heterozygous \(Hb^A\) and \(Hb^S\) individuals are malaria-resistant yet healthy.
• Homozygous \(\mathrm{Hb}^5\) individuals have sickle cell disease.

Understanding these interactions is vital in predicting disease susceptibility and resistance, making organismal genetics crucial for medicine and health.

Population Genetics

Population genetics concerns the distribution of and changes in allele frequencies across populations over time. It links genetics with evolutionary biology.

In the exercise, the discussion about sickle cell prevalence and its effect on population health exemplifies population genetics. It considers how particular genetic traits, like those leading to sickle cell anemia, spread through and affect populations.

• High prevalence of sickle cell trait in malaria-prone regions illustrates evolutionary adaptation.
• Genetic disorders can shape population structures.
• Disease frequency and survival rates are crucial elements.

By studying population genetics, we can track genetic disorders and understand how certain traits provide evolutionary advantages or disadvantages.