Category: Cells

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Make Like a Cell and Split: Comparing Mitosis and Meiosis

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Your body is made up of trillions of cells that all originate from just one—a fertilized egg. The massive multiplication of cells after conception is possible thanks to cell division, which occurs when one cell splits into two. Cell division not only enables growth but also replaces damaged or dead cells and makes reproduction possible. There are two kinds of cell division: mitosis and meiosis.

On the left, a cell goes through the stages of mitosis to split into two cells that each have two sets of chromosomes. On the right, a cell goes through the phases of meiosis to divide into four cells that each have a single set of chromosomes. Mitosis is shown on the left, and meiosis is shown on the right. Credit: Judith Stoffer. Click to enlarge
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Cool Images: Beautiful Bits of Blue

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Most cells are naturally colorless, which is why scientists often use fluorescent tags and other tools to color cell structures and make them easier to study. (Check out the Pathways imaging issue for more on scientific imaging techniques). Here, we’re showcasing cell images that feature shades of blue. Visit our Image and Video Gallery for additional images of cells in all the colors of the rainbow, as well as other scientific photos, illustrations, and videos.

Cool Images
Many blue circles, each surrounded by yellow dots. All the structures are encased in gray webs.
Credit: Torsten Wittmann, University of California, San Francisco.
A large circle made up of light blue dots, with darker blue spots underneath and outside of it.
Credit: California Institute for Regenerative Medicine.
Two blue circles encapsulated in red threads and surrounded by other scattered blue circles.
Credit: Deepak Srivastava, Gladstone Institutes, via CIRM.

This image shows lysosomes (purple) within nerve cells that surround amyloid plaques (blue) in a research model of Alzheimer’s disease. Lysosomes help the body dispose of proteins and other molecules that have become damaged or worn out. Scientists have linked the accumulation of lysosomes around amyloid plaques to impaired waste disposal in nerve cells. This impairment ultimately causes nerve cell death, a hallmark of Alzheimer’s disease.

Mitochondria appear in yellow and cell nuclei in blue in this photo of cow cells. The gray webs are the cells’ cytoskeletons. Mitochondria generate energy, nuclei store DNA, and the cytoskeleton gives cells shape and support.

Here, stem cells (light blue) are growing on fibroblasts (dark blue). Stem cells are of great interest to researchers because they can develop into many different cell types. Fibroblasts are the most common cell type in connective tissue. They secrete collagen proteins that help build structural frameworks, and they play an important role in wound healing.

These smooth muscle cells were grown from stem cells. Smooth muscle cells are found in the walls of certain organs, such as the stomach, and can’t be controlled voluntarily. Red indicates smooth muscle proteins, and blue indicates nuclei.

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Science Snippet: Apoptosis Explained

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Apoptosis is the process by which cells in the body die in a controlled and predictable way because they have DNA damage or are no longer needed. The term comes from a Greek word meaning “falling off,” as in leaves falling from a tree.

When a cell undergoes apoptosis, it shrinks and pulls away from its neighbors. As the cytoskeleton that gives it shape and structure collapses, the envelope around the cell’s nucleus breaks down, and its DNA breaks into pieces. Its surface changes, signaling its death to other cells and leading a healthy cell to engulf the dying one and recycle its components.

On the left, two large cells with clear, smooth edges. On the right, two smaller cells with ragged edges.
Two cells in a healthy state (left) and entering apoptosis (right). Credit: Hogan Tang of the Denise Montell Lab, Johns Hopkins School of Medicine.
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Cool Video: A Biological Lava Lamp

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Several spheres contorting and lighting up inside a cone-shaped structure.
Credit: Jasmin Imran Alsous and Jonathan Jackson, Martin Lab, Massachusetts Institute of Technology.

What looks like a bubbling lava lamp is actually part of an egg cell’s maturation process. In many animals, the egg cell develops alongside sister cells. These sister cells are called nurse cells in the fruit fly (Drosophila melanogaster), and their job is to “nurse” an immature egg cell, or oocyte. Toward the end of oocyte development, the nurse cells transfer all their contents into the oocyte in a process called nurse cell dumping. This video captures this transfer, showing significant shape changes on the part of the nurse cells (blue), which are powered by wavelike activity of the protein myosin (red).

Researchers created the video using a confocal laser scanning microscope. Learn about this type of microscope and other scientific imaging tools by stepping into our virtual imaging lab, and check out more basic science videos and photos in the NIGMS Image and Video Gallery.

This post is a great supplement to Pathways: The Imaging Issue.

The video was taken using a confocal laser scanning microscopy (sometimes shortened to just “confocal microscopy”), one of the techniques mentioned in the Pathways timeline (1970s).

Learn more in our Educator’s Corner.

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Career Conversations: Q&A with Molecular Biologist Hong Liu

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A scientist wearing a lab coat and holding a pipette in front of a workbench with scientific instruments.
Dr. Hong Liu in the lab.
Credit: Courtesy of Dr. Hong Liu.

“A scientific career is really worth it,” says Hong Liu, Ph.D., an assistant professor of biochemistry and molecular biology at Tulane University School of Medicine in New Orleans, Louisiana. Check out the highlights of our interview with Dr. Liu below to learn about his journey as a scientist and his advice for students.

Q: What makes a career in science exciting?

A: I think there are at least two things that make a science career very exciting. The first is that doing science means you have freedom to explore a lot of new ideas. The second thing is it’s rewarding. The “rewarding” I’m talking about here is not like how much money you can make. It’s rewarding in the answers you find and the new knowledge you reveal.

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A Focus on Microscopes: See Eye-Catching Images

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Have you ever wondered what creates striking images of cells and other tiny structures? Most often, the answer is microscopes. Many of us have encountered basic light microscopes in science classes, but those are just one of many types that scientists use. Check out the slideshow to see images researchers have captured using different kinds of microscopes. For even more images of the microscopic world, visit the NIGMS Image and Video Gallery.

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Career Conversations: Q&A with Microbiologist Josephine Chandler

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Josephine (Josie) Chandler, Ph.D., first became interested in science when she took a high school chemistry class. In college, she fell in love with microbiology and ultimately earned a Ph.D. in the field. Today, she’s an associate professor of molecular biosciences at the University of Kansas in Lawrence, where her lab investigates interactions in bacterial communities. By better understanding these interactions, scientists may find new ways to stop infections or break down environmental pollutants—a process known as bioremediation.

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Science Snippet: Learn About the Cytoskeleton

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A treelike structure made up of red and green fibers.
A cow cell showing actin filaments (red) and microtubules (green). Credit: Tina Carvalho, University of Hawaii at Manoa.

The cytoskeleton is a collection of fibers that gives shape and support to cells, like the skeleton does for our bodies. It also allows movement within the cell and, in some cases, by the entire cell. Three different types of fibers make up the cytoskeleton: actin filaments, intermediate filaments, and microtubules.

Powering Muscles

Actin filaments contract or lengthen to give cells the flexibility to move and change shape. Along with the protein myosin, they’re responsible for muscle contraction, including voluntary movement and involuntary muscle contractions, such as our heartbeats. Actin filaments are the thinnest and most brittle of the cytoskeletal fibers, but they’re also the most versatile in terms of shape.

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Cool Images: Wondrous Worms

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The tiny roundworm Caenorhabditis elegans is one of the most common research organisms—creatures scientists use to study life. While C. elegans may seem drastically different from humans, it shares many genes and molecular pathways with us. Viewed with a microscope, the worm can also be surprisingly beautiful. Aside from the stunning imagery, these examples from our Image and Video Gallery show how C. elegans helps scientists advance our understanding of living systems and find new ways to improve our health.

Round yellow shapes with smaller blue spots. Three of the yellow shapes are connected by a purple line. Credit: Keir Balla and Emily Troemel, University of California San Diego.

This C. elegans has been infected with microsporidia (purple), parasites closely related to fungi. The yellow shapes are the worm’s gut cells, and the blue dots are nuclei. Some microsporidia can infect people, so studying the parasites in worms could help researchers devise strategies to prevent or treat infections.

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Engage Learners in Science and Health With Our Kahoots!

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NIGMS, in collaboration with Scholastic, has developed a collection of free biology and health activities on the educational app Kahoot! You can play them alone, with friends, or with a class of students. Four Kahoots! are currently available:

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