Factual knowledge
Briefly describe one new piece of factual knowledge that you acquired or developed since the start of the course.
I’ve learned that nutrition can play an important role in determining the developmental pathway of an organism, when we learned how drone, worker, and queen bees develop. By feeding bee larvae royal jelly, they grow larger and have higher rates of fertility and longevity which help them with reproduction and expanding the hive. On the contrary, drone and worker bees are fed “bee bread”, which is a combination of pollen and honey that doesn’t provide the same nutrients as royal jelly. As a result, they develop better foraging abilities. The bees’ diet controls their development through genetic interactions, where a protein in royal jelly causes methylation of DNA, unwinding it, and allowing replication of specific genes to occur. The genes that end up being expressed are those contribute to the formation of female reproductive organs, and fertility.
Making connections (conceptual knowledge!)
How does this new piece of knowledge fit into what you already knew?
Learning that an organism’s diet can control the methylation of their DNA, and therefore, the expression of certain genes, fit into the concept of how diet and nutrition can alter growth, development, and body shape. However, before learning this, I only thought diet had control over body type through provision of vitamins and other nutrients that act as co-factors in enzymatic biochemical reactions. It was their role in genetics and gene expression that was a brand new idea for me.
What other facts is it connected to, and how?
Proteins from food acting as regulators of gene expression is connected to the whole idea of constitutive and facultative expression of genes through methylation. DNA exists in two forms: euchromatin, when it is loosely wound around DNA, and heterochromatin, when it is tightly packed and genes are not being expressed. Heterochromatin can also be found in constitutive and facultative forms, where facultative heterochromatin is sometimes wound tightly, and sometimes unwound. To achieve this flexibility, the DNA can be methylated in order to interfere with the interactions between its backbone and histone proteins. This is how DNA methylation allows access of transcription factors to DNA, and increases gene expression.
Does it fit into any concepts? How?
The idea of proteins in diet affecting gene expression, which in turn affects morphology fits into multiple concepts:
1. Gene Regulation: As mentioned previously, proteins can cause methylation of DNA, allowing gene expression to increase.
2. Diet affecting morphology: Proteins in the diet can affect an organisms size, behaviour, fertility, and other characteristics.
Other comments (optional)
Please feel free to include any additional comments that you wish to share.
It would be interesting to know if there are any nutrients, foods, or diets that can cause noticeable changes in humans. For example, could eating a certain food (that contains some protein or vitamin), affect humans behaviour, size, or fertility?
Many attributes of morphology are assumed to be 100% dependent on genetics, such as height, or hair color. However, could humans create a diet that fosters the development of certain morphologies such as taller people, or people with darker hair? The bee example seems to suggest that this may be possible.
I have heard that certain foods act as aphrodisiacs for humans. If true, do these foods act through a protein/gene expression pathway, a hormonal pathway, or by some other mechanism? It would be interesting to understand.