AP Biology class blog for discussing current research in Biology

Tag: Mitosis

The epigenome can be effected by pollution

A Thing Floating in the Lake

The epigenome is a lesser known part of the study of genetics. It consists of the parts of the genome which are not part of the DNA, for example transcription factors and the accessibility of different sections of the chromatin. DNA in the cell is wrapped around proteins called histones. The wrapping of DNA around these histones are also a factor which controls which parts of the DNA are read into proteins. Furthermore, DNA methylation is an important regulatory factor. The addition of methane groups to DNA makes it impossible to read, effectively shutting off the gene that is methylating.

The epigenome is unique because it can be changed significantly in response to external stimuli. In a way, it is the body’s way of altering DNA on the fly, without actually altering the genetic code. The epigenome can also plays a role in cell differentiation. In class, we discussed how all cells have identical genetic code, passed down from one cell to another. All cells start the same and eventually change into all the different types. The epigenome helps to control exactly which parts of the genome are expressed. It is the epigenome which controls which parts of the genetic code are expressed.

However, the epigenome is still passed down hereditarily and down cell lines. As cells divide through mitosis or meiosis, the epigenome is passed down to the daughter cells. This combination of constant adaptation and persistence through generations make the epigenome an essential part of the body’s function. The combo also makes the epigenome a key part of how the body can be changed for a significant period of time by negative stimuli. These effects can even span generations and have been shown to effect the course of evolution.

Recently, scientists at the University of Liverpool have demonstrated exposure to pollution in water fleas has effects that last over 15 generations. When exposed to a pollutant for a period of 7 months, which encompasses 15 generations of fleas, scientists observed increased rates of DNA methylation. When transferred back to clean water, the scientists found that DNA methylation remained the same. Thus, the pollution permanently damaged the epigenome of the fleas.

Harnessing the Power of Regeneration

You at one point might have wished for this superpower after a broken bone. This ability to regenerate is natural to some animals like salamanders and starfish. Recently researchers did the unthinkable; they were able to regenerate a limb for our small amphibian friend. 

Even though you may think that we don’t have regenerative powers, we have the ability to heal from a cut. However, we do not have the ability to regenerate an arm or a leg like a starfish. Instead, when we lose an arm, our body uses scar tissue to cover it. This is a very common mechanism in a lot of animals to prevent blood loss and bacterial infection. 

Researchers at Tufts and Harvard universities worked together to develop a 5 drug cocktail that is used to regenerate their limbs, bones, and nerves instead of just simply clotting it. In their experiment, the animal being tested is the African clawed frog. There are 5 drugs in this process and a silk protein gel. First, the researchers put 5 drugs and the gel in the silicone wearable bioreactor dome that is attached to the frogs’ limbs. Once the drugs are in contact with the stump, the drugs stop the inflammation while also inhibiting collagen production. The importance of stopping collagen production is that it prevents scarring so the researchers can attempt to regrow the limb. The rest of the drugs encourage the growth of nerve fibers, blood vessels, and muscle that makes the limb function as a normal limb. The most amazing thing about this process is that the frog only needs to wear the silicone wearable bioreactor dome for 24 hrs and only be exposed to the drugs once; this will kickstart an 18-month journey of regeneration.

Mitosis cells sequence

A Diagram showing the Interphase, Prophase, Prometaphase, Metaphase, Anaphase, and Telophase in Mitosis.


To understand how regeneration is happening, it is crucial to understand the process called mitosis. Mitosis happens when the cell is not in the interphase. If the cell passes the G1, G2, and mitosis checkpoint mitosis and cytokinesis will happen. Mitosis starts as a diploid cell with double-stranded Chromosomes but ends with cytokinesis, resulting in 2 genetically identical daughter cells that are diploid but single-stranded. After this process, the cell will go back to the interphase and G1 phase where the cell grows preparing for its next mitosis cycle. Mitosis is crucial for regeneration since it produces millions of cells in the frog’s body for a new limb to grow. With successful testing on amphibians, Michael Levin, a researcher on this project, said that they will “be testing how this treatment could apply to mammals next.” 

This advancement in medical technology only serves to bring hope to future advancements like limb regeneration of human embryos. With so many people’s lives that can be changed for the better, I cannot wait for the future where we fully harness the power of biology. What do you think about this technology, and do you have ideas for other applications? Are there any downsides that you see?

ITS ALIVE!!! Scientists bring their creation to life.

Cells are the basic units of life, but now scientists found a way to take matters into their own hands and actually create their own Frankenstein of cells. Scientists first created a single-celled organism with only 473 genes five years ago. Unlike the most recent cellular innovation, this simple cell grew and divided into cells of strange and unusual shapes and sizes. In an attempt to fix this, scientists identified 7 genes that when added to the cell, cause them to divide into perfectly uniform shapes. The J. Craig Venter Institute (JCVI), the National Institute of Standards and Technology(NIST), and the Massachusetts Institute of Technology(MIT) Center for Bits and Atoms all together can be accredited with this success.Cell division

How Was It Done?

The first cell with a synthetic genome was created in 2010 by the scientists at JCVI. Rather than building a cell from scratch, they started with cells from a simple bacteria called mycoplasma. The DNA already in those cells were destroyed and replaced with computer designed DNA. Thus lead to the first ever organism on Earth to have an entirely synthetic genome. It was named “JCVI-syn1.0”. Since then scientists have been working on stripping it down and reaching its minimum genetic components. Now scientists added 19 genes into this cell(including the 7 genes needed for proper cell division) and call it JCVI-syn3A. This cell variant also has fewer than 500 genes(a human cell has about 30,000). To find those 7 genes the JCVI synthetic biology group, led by John Glass and Lijie Sun, constructed multiple variants by adding and removing genes. NIST had to observe and measure the changes under a microscope. The difficulty here lay in observing the cells while they were alive, which made imaging them harder because of how small and fragile they were. Even the smallest of force could rupture them. Strychalski and MIT co-authors James Pelletier, Andreas Mershin and Neil Gershenfeld designed a microfluidic chemostat to remedy this. The article by NIST best describes this as a “sort of mini-aquarium where the cells could be kept fed and happy under a light microscope”. They discovered two known cell division genes, ftsZ and sepF, a hydrolase of unknown substrate, and four genes that encode membrane-associated proteins of unknown function, were all required together for cell division. As we learned in AP Bio, organelles like mitochondria and chloroplasts are also autonomous. That simply means that they are self replicating similar to this man-made cell.


The ability to create synthetic cells could lead to potential cells that produce drugs, foods and even fuels. Others can detect disease and the drugs to treat it all while being inside your body. It’s amazing to think that humans are capable of creating synthetic life on a molecular level. One can only hope that this power is used for good in the future. Do you believe that what these scientists are doing is ethical or is “playing God” tampering with forces unknown? 

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