In the globin gene family (shown in the below diagram), which pair of genes would exhibit a higher level of sequence similarity, the human δ-globin and human β-globin genes or the human β-globin and chimpanzee β-globin genes? Can you explain your answer in terms of the timing of gene duplications?

Verified step by step guidance

1. Understand the globin gene family: The globin gene family consists of genes that encode globin proteins, which are part of hemoglobin. These genes have evolved through gene duplication events, followed by divergence over time.
2. Identify the gene pairs in question: The problem compares the sequence similarity between (1) human δ-globin and human β-globin genes, and (2) human β-globin and chimpanzee β-globin genes.
3. Consider the evolutionary timeline: Gene duplications, such as the one that produced δ-globin and β-globin, occurred earlier in evolutionary history. This means that these genes have had more time to accumulate mutations and diverge in sequence.
4. Compare species divergence: The human β-globin and chimpanzee β-globin genes are orthologous genes, meaning they are derived from a common ancestor and have diverged only since the human-chimpanzee lineage split. This divergence is more recent compared to the duplication event that created δ-globin and β-globin.
5. Conclude based on timing: Since the human β-globin and chimpanzee β-globin genes have had less time to diverge compared to the human δ-globin and human β-globin genes, the former pair would exhibit a higher level of sequence similarity. This is due to the more recent common ancestry of the orthologous genes.

Key Concepts

Gene Duplication

Gene duplication is a process where a segment of DNA is copied, resulting in two identical or similar genes. This can lead to genetic redundancy, allowing one gene to maintain its original function while the other may evolve new functions. Understanding the timing of these duplications is crucial for analyzing genetic similarities, as genes that diverged more recently are likely to show higher sequence similarity.

Sequence Similarity

Sequence similarity refers to the degree to which two DNA, RNA, or protein sequences resemble each other. It is often measured using various algorithms that assess the alignment of sequences. Higher sequence similarity typically indicates a more recent common ancestor or shared evolutionary history, which is essential for comparing genes from different species or within a gene family.

Phylogenetic Relationships

Phylogenetic relationships describe the evolutionary connections between different species or genes based on their genetic information. By constructing phylogenetic trees, scientists can visualize how closely related different genes or organisms are, which helps in understanding the timing of gene duplications and the evolutionary history of gene families, such as the globin gene family.