Tag: Cellular Processes

Posted on

Science Snippet: The Marvels of Membranes

by
2 comments

Like skin that covers and protects our bodies, membranes surround and protect cells and organelles. Membranes are semi-fluid barriers composed mainly of lipids and proteins. They provide structure; control the import and export of molecules such as ions, nutrients, and toxins; and support cellular communication.

An illustration of a cell cut in half with gray lines indicating its borders and borders of adjacent cells. The cell contains a variety of round and oblong structures in several colors.
A cross section of a cell with its membrane and adjacent cell membranes outlined in gray. The colorful structures are organelles with membranes. Credit: Judith Stoffer.

The lipids that compose membranes are primarily phospholipids. (Cholesterol is another lipid often present in membranes that helps regulate their stiffness.) Phospholipids have hydrophilic (water-loving) “heads” and hydrophobic (water-fearing) “tails.” Within the human body, a water-loving environment, they line up so that their tails face one another and their heads point outward. In membranes, this alignment makes a bilayer barrier that is two lipid molecules deep.

Continue reading “Science Snippet: The Marvels of Membranes”
Posted on

In Other Words: The Pathways Inside Our Bodies

by
0 comments

For many people, the word pathway may bring to mind stepping stones in a garden or a trail through a forest. But when biologists talk about a pathway, they’re referring to a series of actions among molecules in a cell that leads to a certain product or change within that cell. Pathways maintain balance during walking, control how the eyes’ pupils respond to light, and affect skin’s reaction to changing temperature. They control our bodies’ responses to the world, and errors in them can lead to disease.

Continue reading “In Other Words: The Pathways Inside Our Bodies”
Posted on

Make Like a Cell and Split: Comparing Mitosis and Meiosis

by
12 comments

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
Continue reading “Make Like a Cell and Split: Comparing Mitosis and Meiosis”
Posted on

In Other Words: Translation Isn’t Only for Languages

by
0 comments

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 large speech bubble with the word “hello” surrounded by smaller speech bubbles with greetings in other languages, and on the right is a ribosome producing a protein. 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.
Continue reading “In Other Words: Translation Isn’t Only for Languages”
Posted on

Science Snippet: Apoptosis Explained

by
5 comments

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.
Continue reading “Science Snippet: Apoptosis Explained”
Posted on

Cool Video: A Biological Lava Lamp

by
1 comment
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.

Posted on

Career Conversations: Q&A with Molecular Biologist Hong Liu

by
0 comments
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.

Continue reading “Career Conversations: Q&A with Molecular Biologist Hong Liu”
Posted on

Dairy Deconstructor: How an Enzyme Enables Milk Digestion

by
0 comments

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.

Continue reading “Dairy Deconstructor: How an Enzyme Enables Milk Digestion”
Posted on

Pumping Iron: The Heavy Lifting Iron Does in Our Bodies

by
0 comments

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
Continue reading “Pumping Iron: The Heavy Lifting Iron Does in Our Bodies”
Posted on

Take a Tour of Your Cells’ Organelles!

by
0 comments
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.

Continue reading “Take a Tour of Your Cells’ Organelles!”