Highly proliferative cells are a normal and healthy part of some tissue types. Read on to learn what you need to know about this highly regulated process for the MCAT.
Cell proliferation is a high-regulated process that is vital for the development and maintenance of healthy tissue. Certain types of tissue contain highly proliferative cells, a concept that the MCAT could test you on.
Learning the fundamental processes of optimal health and growth will be important in your journey as a medical professional. Read on to learn what you should know about highly proliferative cells for the MCAT.
Cell proliferation occurs as a cell grows and divides into two daughter cells through cell division. This complex and highly regulated process increases cell number and allows for the replenishment of cells in healthy, normal tissue. Cell proliferation is also essential to development in all multicellular organisms, starting from embryogenesis.
Certain types of cells have different degrees of cell proliferation. Most cells in adult animals enter the G0 phase of the cell cycle, also known as a resting state.
However, many types of differentiated cells, which include smooth muscle cells, epithelial cells of the internal organs, liver cells, prostate cells, and more, will reenter the cell cycle and resume proliferation when necessary. For instance, if a kidney is damaged through surgery or injury, the remaining cells will undergo proliferation to regenerate any lost cells.
Other types of cells, such as human cardiac muscle cells and neuron cells, cannot be replaced or go under cell division once they are made during embryonic development. What you have is what you got!
On the opposite end of the spectrum are cells with short lifespans that need to be constantly replaced by cell proliferation, such as blood cells and epithelial skin cells.
These highly proliferative cell types don’t directly proliferate themselves, but are instead replaced by the proliferation of stem cells. Stem cells are less differentiated and can divide to produce cells that either remain as stem cells or go on to differentiate into other types of cells.
While proliferation is a vital process in healthy tissues, cancer cells also use proliferation to divide and spread. The more rapid the proliferation, the faster and more aggressively a cancerous tumor can grow.
There are specific genes that regulate normal cell proliferation. When these genes are mutated, they can increase the potential of cancer by promoting uncontrollable cell division. These mutations are called oncogenes.
Tumor suppressor genes, on the other hand, act to control cell division and proliferation. Mutations in these genes can also increase cancer risk.
Questions on highly proliferative cells appear in the Biological and Biochemical Foundations of Living Systems section of the MCAT. Success on these questions will depend on knowledge of the functions and proliferation rates of different cell types.
For instance, intestinal epithelial cells have the highest proliferation rates in adult humans. As a type of lining, these cells are commonly damaged and need replacement due to the pathogen, high PH, and harsh environments they endure.
After learning all you can on highly proliferative cells on the MCAT, it’s always a good idea to put your newly-attained knowledge to the test. One of the best ways to determine how well you know a topic on the MCAT is by doing practice tests. Here are a few sample questions that can help you gauge how well you grasp highly proliferative cells on the MCAT.
Which of the four cell types below has the highest rates of proliferation in adult humans:
A) Neural cells
B) Epithelial cells of the GI tract
Answer: B) Epithelial cells of the GI tract
For the same reason as explained above, epithelial cells of the GI tract have the highest proliferation rate of any cell type in adult humans. While hepatocytes can also proliferate in adult humans, the question asks for the highest rate. Adipocytes, used in energy storage, are not very proliferative. Similarly, neural cells do not proliferate past differentiation.
A Helicobacter pylori infection may lead to an increase in gastric mucosal cells' proliferation rates. These rates could result in gastric cancer when:
A) Novel genetic mutations arise in somatic cells undergoing proliferation
B) Novel genetic mutations arise in germs cells undergoing proliferation
C) Novel genetic mutations arise in the bacterial cells
D) There is an increase in antibodies to H. pylori
Answer: A) Novel genetic mutations arise in somatic cells undergoing proliferation
Novel genetic mutations arising in proliferating somatic cells are the most reasonable cause of gastric cancer in this case. This question states that there is a connection between gastric cancer and the increase in proliferation rates of gastric mucosal cells. Gastric mucosal cells are classified as somatic cells and not germ line cells (answer b), as germ line cells are located only in the gonads.
Mutations in the genes of somatic cells can affect these cells' ability to regulate cell division, and uncontrolled cell division can lead to cancer. Mutations in the gonads and bacterial cells and an increase in immune response (answers b, c, and d) are not likely to cause uncontrolled cell division in somatic gastric mucosal cells.
Below are some frequently asked questions about highly proliferative cells on the MCAT.
Highly proliferative cell types include epithelial cells of the internal organs, such as the GI tract, kidney, liver, breast, skin fibroblasts, smooth muscle cells, and endothelial cells that line blood vessels.
GI epithelial cells are highly proliferative and have a high turnover rate.
While adipocytes are essential when it comes to energy storage, they tend to change in size but not quality. Therefore, they are not very proliferative.
Cells that are proliferative go through the process of cell growth and division, resulting in an increase in the number of that type of cell.
Cell proliferation is a normal regulatory process in healthy tissues to maintain a normal number of cells. It can also occur in response to tissue damage or certain mutations.
Gene regulatory networks control normal cell proliferation. Nutrients, growth factors, mutations, and the degree of differentiation of the tissue type also contribute to the control of cell proliferation.
Cell proliferation refers to an increase in the number of cells through the process of cell growth and division. Specifically, this cell number increases through a process of cell division called mitosis. So while cell proliferation is not synonymous with mitosis, mitosis is an important part of normal cell proliferation.
Highly proliferative cells are those that have a high turnover rate. They can occur in healthy tissue during development and adulthood, but can also perpetuate the growth of cancerous tumors. As an inspiring doctor, familiarizing yourself with this vital process will help you succeed on the MCAT and beyond.