Genetics Made Easy
Genes are segments of DNA that contain the code for specific proteins or RNA molecules, which are crucial for various cellular functions. They are fundamental units of heredity and determine many of our traits and characteristics.
DNA (Deoxyribonucleic Acid)
Stores genetic information
It is structured as a double helix, with four nucleotide bases: adenine (A), guanine (G), cytosine (C), and thymine (T) that pair in a specific manner (A-T and G-C)
Chromosomes
Thread-like structures made of DNA and proteins
Humans have 23 pairs of chromosomes, totaling 46 chromosomes in each cell
Cells
Basic units of life
Contain the nucleus where DNA is stored in chromosomes
Every cell (except gametes) contains a complete set of chromosomes
How Genetic Information is Stored and Passed Down?
Storage of Genetic Information
Genetic information is stored in the sequences of DNA based, grouped into genes. These genes provide instructions for making proteins, which are essential for the structure and function of cells
DNA is replicated during cell division to ensure that genetic information is passed accurately to daughter cells
Passing Down Genetic Information
Inheritance
Parents pass traits to their offspring through genes. Each gene has different versions called alleles, which interact to determine traits like eye color or blood type.
Gene Expression
The process by which genes are turned on or off to produce proteins. This is crucial for cell specialization and overall organism development.
Genetic Variants: Makes Each Person Unique
Genetic variants are the differences in DNA sequences that make each person unique. These variations arise primarily through mutations and play a critical role in diversity, evolution, and inherited traits.
Mutations
Mutations are changes in DNA sequences and the primary drivers of genetic variants. They occur due to:
Germline Mutations
Germline mutations occur in sperm or egg cells and are passed to offspring. These mutations affect every cell in the offspring’s body and are critical for evolution and inherited diseases.
In contrast to somatic mutations which remain confined to the body, germline mutations are the basis of genetic diversity across generations. They contribute to traits like eye color and susceptibility to diseases, while errors in these mutations can lead to inherited disorders.
Genetic variants, shaped by these mechanisms, ensure that no two individuals—except identical twins—share the exact same DNA.
References
- Nature news. https://www.nature.com/scitable/topicpage/inheritance-of-traits-by-offspring-follows-predictable-6524925/
- Loewe, L. (2008) Genetic mutation. Nature Education 1(1):113
- Stallard, T. (2023) Rare disease care across asia pacific, Sandpiper.
- Hlawulani (2019) New Scientific Paper confirms 300 million people living with a rare disease worldwide, Rare Diseases International.
- Pesheva, E. (2023) Researchers able to determine the effects of genes and environment in 560 common conditions, Harvard Gazette.
- Hanany, M., Rivolta, C., & Sharon, D. (2020). Worldwide carrier frequency and genetic prevalence of autosomal recessive inherited retinal diseases. Proceedings of the National Academy of Sciences, 117(5), 2710–2716. https://doi.org/10.1073/pnas.1913179117
- Abdul, Q. A., Yu, B. P., Chung, H. Y., Jung, H. A., & Choi, J. S. (2017). Epigenetic modifications of gene expression by lifestyle and environment. Archives of Pharmacal Research, 40(11), 1219–1237. https://doi.org/10.1007/s12272-017-0973-3
- Alegría-Torres, J. A., Baccarelli, A., & Bollati, V. (2011). Epigenetics and Lifestyle. Epigenomics, 3(3), 267–277. https://doi.org/10.2217/epi.11.22
- CDC. (2025, January 31). Epigenetics, Health, and Disease. Genomics and Your Health. https://www.cdc.gov/genomics-and-health/epigenetics/index.html
- Advantages of NGS Over Other Molecular Methods. (2020). Illumina.com. https://sapac.illumina.com/science/technology/next-generation-sequencing/beginners/advantages.html
- UF scientists test mouthwash method of collecting DNA – UF Health. (2023). Ufhealth.org. https://ufhealth.org/news/2002/uf-scientists-test-mouthwash-method-collecting-dna
- Zayats, T., Young, T. L., Mackey, D. A., Malecaze, F., Calvas, P., & Guggenheim, J. A. (2009). Quality of DNA Extracted from Mouthwashes. PLoS ONE, 4(7). https://doi.org/10.1371/journal.pone.0006165
- Lelieveld, S. H., Spielmann, M., Mundlos, S., Veltman, J. A., & Gilissen, C. (2015). Comparison of Exome and Genome Sequencing Technologies for the Complete Capture of Protein-Coding Regions. Human Mutation, 36(8), 815–822. https://doi.org/10.1002/humu.22813
- Zhao, Y., Fang, L. T., Shen, T., Choudhari, S., Talsania, K., Chen, X., Shetty, J., Kriga, Y., Tran, B., Zhu, B., Chen, Z., Chen, W., Wang, C., Jaeger, E., Meerzaman, D., Lu, C., Idler, K., Ren, L., Zheng, Y., & Shi, L. (2021). Whole genome and exome sequencing reference datasets from a multi-center and cross-platform benchmark study. Scientific Data, 8(1). https://doi.org/10.1038/s41597-021-01077-5
- Barbitoff, Y. A., Polev, D. E., Glotov, A. S., Serebryakova, E. A., Shcherbakova, I. V., Kiselev, A. M., Kostareva, A. A., Glotov, O. S., & Predeus, A. V. (2020). Systematic dissection of biases in whole-exome and whole-genome sequencing reveals major determinants of coding sequence coverage. Scientific Reports, 10(1). https://doi.org/10.1038/s41598-020-59026-y
