Genes, Proteins and Phenotype
This lesson covers:
- The relationship between genes, proteins, and phenotypes
- Examples of relationships between genes, proteins, and phenotypes
The relationship between genes, proteins, and phenotypes
There is an intricate relationship between genes, the proteins they encode, and the eventual phenotypic effects. This connection is fundamental to understanding how genetic information translates into physical traits.
Key concepts:
- Genes provide the code to produce proteins with specific amino acid sequences.
- Mutations in genes can change the amino acid sequence of proteins.
- Disrupted protein structure and function impacts cellular processes.
- Abnormal processes cause differences in phenotype.
Even small changes to gene sequences can disrupt protein structure and function, impacting metabolic pathways and developmental processes.
Examples of relationships between genes, proteins, and phenotypes
Understanding the relationships between specific genes, the proteins they encode, and how mutations in these genes can affect the phenotype is crucial.
Below are a few examples that you need to know, which illustrate these connections.
| Gene | Function of the gene | Dominance of the faulty allele | Effects of gene mutation | Condition the faulty allele causes | Characteristics of the condition |
|---|---|---|---|---|---|
| TYR | Encodes the tyrosinase enzyme | Recessive | Disruption of tyrosinase production leads to a lack of melanin | Albinism | Lack of eye, skin, and hair pigmentation |
| HBB | Encodes the β-globin polypeptide in haemoglobin | Co-dominant | Altered amino acid sequence in β-globin produces less soluble haemoglobin, leading to sickle-shaped red blood cells | Sickle cell anaemia | Deformed red blood cells clump together and reduce oxygen transport |
| F8 | Encodes coagulation factor VIII, a blood clotting protein | Recessive | Impaired factor VIII production or function, causing reduced blood clot formation | Haemophilia | Excessive bleeding from minor injuries |
| HTT | Encodes the huntingtin protein, important for neurone development | Dominant | Excess CAG repeats in the HTT gene result in a mutated huntingtin protein, leading to gradual decay of neurones in the brain | Huntington's disease | Declining motor control and mental abilities later in life |
| Le | Encodes an enzyme involved in gibberellin synthesis | Recessive | Impaired enzyme production and function causes disrupted cell growth | Stunted plant height | Abnormal plant growth |
These examples highlight the direct impact of genetic mutations on protein function and how these changes can lead to significant phenotypic differences. Understanding these relationships helps in the diagnosis and treatment of genetic conditions.