Biology Review
Before we get to the interesting idea that humans may have genes (instructions to make proteins) beyond what we already know, here is a biology review.
What is a Chromosome?
A chromosome is a thread-like structure found in the nucleus of cells in animals and plants, including humans. It is made of DNA, which carries genetic information essential for the growth, development, and functioning of an organism. Humans typically have 46 chromosomes in each cell, arranged in 23 pairs. Each chromosome contains many genes, which are segments of DNA that provide instructions for making proteins or RNA molecules[1][2][3][4][5].
What is DNA?
DNA, or deoxyribonucleic acid, is the molecule that holds the genetic instructions for life. It is like a blueprint for building and maintaining an organism. DNA is organized into chromosomes, which help keep it compact and protected within the cell. The DNA molecule is structured as a double helix, resembling a twisted ladder, with bases that pair specifically: adenine with thymine and guanine with cytosine[1][2][5].
What is a Gene?
A gene is a segment of DNA that contains the code for a specific protein or functional RNA molecule. Genes are responsible for determining traits and characteristics in an organism. They play a crucial role in controlling the synthesis of proteins, which are vital for various bodily functions[1][2][5].
What is a Bacteria?
Bacteria are single-celled microorganisms found everywhere on Earth, from soil to water to the human body. They are much simpler than human cells and typically have one or two circular chromosomes. Bacteria can reproduce quickly and adapt to many environments. Some bacteria are beneficial, like those in our gut that aid digestion, while others can cause diseases.
What is a Plasmid?
A plasmid is a small, circular piece of DNA found in bacteria, separate from their main chromosome. Plasmids often carry genes that provide advantages, such as antibiotic resistance, and can be shared between bacteria. This sharing allows bacteria to quickly adapt to new challenges.
What is a Virus?
A virus is a tiny infectious agent that can only reproduce inside the cells of a living organism. Viruses are much smaller than bacteria and are not considered living because they cannot carry out life processes on their own. They invade host cells and use the host’s machinery to make more viruses, often causing disease.
What is a Mitochondria?
Mitochondria are small structures within cells, often referred to as the “powerhouses” of the cell because they produce energy. They have their own DNA, separate from the DNA found in the nucleus, and are believed to have originated from bacteria that were engulfed by early eukaryotic cells.
What is Cancer?
Cancer is a disease characterized by the uncontrolled growth and division of cells. It can occur when genetic changes disrupt the normal regulation of cell growth, leading to the formation of tumors. Cancer can spread to other parts of the body and is influenced by genetic, environmental, and lifestyle factors.
Recent Research Article
Recent research from Columbia University has found that bacteria can create free-floating genes outside of their usual chromosomal structures. This challenges the idea that genetic instructions are only found in chromosomes and suggests that similar genes might exist in humans. Bacteria use an enzyme called reverse transcriptase to make these genes, which help them defend against viruses.
In humans, we already have some DNA that exists outside of chromosomes, known as extrachromosomal DNA (ecDNA). One important type of ecDNA is mitochondrial DNA. Mitochondria are tiny structures in our cells that produce energy, and they likely originated from bacteria that were absorbed by early cells. Another type of ecDNA in humans is called extrachromosomal circular DNA (eccDNA). EccDNA is linked to different body systems and diseases, especially cancer.
In cancer cells, ecDNA often contains many copies of genes that can cause tumors to grow, make them resistant to drugs, and lead to genetic instability. This DNA is different from the DNA in the cell nucleus because it has less chemical modification and unique sequences. The presence of ecDNA in cancer cells is associated with worse outcomes because it helps cancer adapt quickly and become more diverse.
Additionally, bacteria have another type of extrachromosomal DNA called plasmids. Plasmids often carry genes that help bacteria survive, like those that provide antibiotic resistance, and can be shared between different bacteria. There are also cryptic plasmids, which don’t have obvious benefits but can still transfer genetic material.
The researchers at Columbia University are exploring whether humans have similar extrachromosomal genes that could be important for normal body functions and genetic therapies. This research could lead to new understandings of how our genes work and new treatments, especially for diseases like cancer where ecDNA is significant.
Read More
[1] https://www.msdmanuals.com/home/fundamentals/genetics/genes-and-chromosomes
[2] https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/genes-and-genetics
[3] https://en.wikipedia.org/wiki/Chromosome
[4] https://www.ncbi.nlm.nih.gov/books/NBK557784/
[5] https://my.clevelandclinic.org/health/body/23064-dna-genes–chromosomes
[6] https://utility0.ncssm.edu/~morrison/2021S2/4280/May/10May21/scrambled.txt
[7] https://gist.github.com/pmarreck/28b3049a1a70b8b4f2eaff4466d0c76a
[8] http://www.mit.edu/~nocturne/athena/text/allwords
[9] https://files.osf.io/v1/resources/489he/providers/osfstorage/5e9695394301660465a09a42?action=download&version=1
[10] https://april.eecs.umich.edu/courses/eecs492_w11/wiki/images/8/82/English.txt
[11] https://bjc.edc.org/June2020bjc2/bjc-r/prog/5-algorithms/U5L1-Spell-Checker.xml
[12] https://users.cs.jmu.edu/foxcj/Public/stemgen/allword.txt
[13] http://web.mit.edu/games/src/mboggle/words/websterwords
[14] https://en.wikipedia.org/wiki/Extrachromosomal_DNA
[15] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9578701/
[16] https://chemh.stanford.edu/news/shining-light-extrachromosomal-dna
[17] https://www.nature.com/articles/s41588-022-01177-x
[18] https://www.sciencedirect.com/topics/medicine-and-dentistry/extrachromosomal-dna
[19] https://www.cuimc.columbia.edu/news/bacteria-encode-hidden-genes-outside-their-genome-do-we
[20] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10055365/
[21] https://www.cuimc.columbia.edu/news/new-gene-editor-harnesses-jumping-genes-precise-dna-integration
[22] https://www.biorxiv.org/content/10.1101/2024.05.08.593200v1
[23] https://pubmed.ncbi.nlm.nih.gov/38428395/
