Tag: Cellular Processes

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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In Other Words: Translation Isn’t Only for Languages


In everyday use, most people understand translation to mean converting words from one language to another. But when biologists talk about translation, they mean the process of making proteins based on the genetic information encoded in messenger RNA (mRNA). Proteins are essential for virtually every process in our bodies, from transporting oxygen to defending against infection, so translation is vital for keeping us alive and healthy.

Below the title “Translation: In Other Words,” two images are separated by a jagged line. On the left is a ribosome producing a protein, and on the right is a large speech bubble with the word “hello” surrounded by smaller speech bubbles with greetings in other languages. Under the images, text reads, “Did you know? In biomedical science, translation refers to the process of making proteins based on genetic information encoded in messenger RNA.”
Credit: NIGMS.
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Science Snippet: Apoptosis Explained


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.

Career Conversations: Q&A with Molecular Biologist Hong Liu

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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Dairy Deconstructor: How an Enzyme Enables Milk Digestion


Did you know that the lack of a single enzyme is responsible for lactose intolerance, a common condition that causes people to have trouble digesting milk? Fortunately, the enzyme is available in an over-the-counter pill for lactose-intolerant people who want to enjoy dairy products. Enzymes are molecules—almost always proteins—that speed up chemical reactions by reducing the amount of energy needed for the reactions to proceed. Without them, many processes in our bodies would essentially grind to a halt.

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Pumping Iron: The Heavy Lifting Iron Does in Our Bodies


Our blood appears red for the same reason the planet Mars does: iron. The element may bring to mind cast-iron pans, wrought-iron fences, or ancient iron tools, but it’s also essential to life on Earth. All living organisms, from humans to bacteria, need iron. It’s crucial for many processes in the human body, including oxygen transport, muscle function, proper growth, cell health, and the production of several hormones.

A graphic showing iron’s abbreviation, atomic number, and atomic weight connected by lines to illustrations of a vial of blood, Mars, and Earth. Iron is the reason both our blood and the planet Mars appear red. The element also makes up the majority of Earth’s core and generates the planet’s magnetic field. Credit: Compound Interest. CC BY-NC-ND 4.0. Click to enlarge
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Take a Tour of Your Cells’ Organelles!

An illustration of a cell cut in half, showing many different structures. A cross-section of a cell showing organelles. Credit: Judith Stoffer.

Welcome to our tour of the cell! Imagine you’ve shrunk down to about 3 millionths of your normal size. You are now about 0.5 micrometers tall (a micrometer is 1/1,000th of a millimeter). At this scale, a medium-sized human cell looks as long, high, and wide as a football field. But you can’t see nearly that far. Clogging your view is a rich stew of molecules, fibers, and various cell structures called organelles. Like the internal organs in your body, organelles in the cell each have a unique biological role to play.

The Nucleus and Its Closest Neighbor

Our first stop is the somewhat spherical structure about 50 feet in diameter. It’s the nucleus—basically the cell’s brain. The nucleus is the most prominent organelle and can occupy up to 10 percent of the space inside a cell. It contains the equivalent of the cell’s genetic material, or DNA.

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Quiz: Prove Your Knowledge of Proteins!


Proteins play a role in virtually every activity in the body. They make up hair and nails, help muscles move, protect against infection, and more. Many NIGMS-funded researchers study the rich variety of proteins in humans and other organisms to shed light on their roles in health and disease.

Take our quiz to test how much you know about proteins. Afterward, find more quizzes and other fun learning tools on our activities and multimedia webpage, which includes an interactive protein alphabet.

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Zinc: Zapping Invaders


Although zinc may appear last on nutrition labels, it’s the second-most abundant trace element in our bodies, behind only iron. (Trace elements are molecules our bodies need in small amounts to stay healthy). Zinc is crucial for a well-functioning immune system, wound healing, physical growth, the senses of taste and smell, and the construction of proteins and DNA. It can also partner with oxygen to form zinc oxide, a compound that scatters ultraviolet light and can act as a protective barrier over inflamed skin. Many sunscreens, burn ointments, diaper creams, and other skin treatments contain zinc oxide.

A graphic showing zinc’s abbreviation, atomic number, and atomic weight connected by lines to illustrations of an I-beam, a cosmetics bottle, and a pill. Zinc may help shorten colds, and it’s part of a compound that can protect skin from ultraviolet light. The element is also used to coat other metals and prevent rusting. Credit: Compound Interest. CC BY-NC-ND 4.0. Click to enlarge
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