Tag: Chromosomes

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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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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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How Errors in Divvying Up Chromosomes Lead to Defects in Cells

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Note to our Biomedical Beat readers: Echoing the sentiments NIH Director Francis Collins made on his blog, NIGMS is making every effort during the COVID-19 pandemic to keep supporting the best and most powerful science. In that spirit, we’ll continue to bring you stories across a wide range of NIGMS topics. We hope these posts offer a respite from the coronavirus news when needed.

Mitosis is fundamental among all organisms for reproduction, growth, and cell replacement. When a cell divides, it’s vital that the two new daughter cells maintain the same genes as the parent.

In one step of mitosis, chromosomes are segregated into two groups, which will go into the two new daughter cells. But if the chromosomes don’t divide properly, one daughter cell may have too many and the other too few. Having the wrong number of chromosomes, a condition called aneuploidy, can trigger cells to grow out of control.

Illustration of two sets of chromosomes being pulled apart. One pair separates evenly and is labeled normal, but the other doesn’t and is labeled aneuploidy.An illustration of chromosomes being segregated equally and unequally during mitosis. Credit: Deluca Lab, Colorado State University.

How chromosome segregation errors disrupt cell division is an important area of research. Although it’s been studied for decades, new aspects are still being uncovered and much remains unknown. NIGMS-funded scientists are studying different aspects of mitosis and chromosome segregation. Understanding the details can provide vital insight into an essential biological process and may also be the key to developing better drugs for cancer and other diseases.

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Looking Back at the Top Three Posts of 2019

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Over the past 12 months, we’ve explored a variety of topics in genetics, cell biology, chemistry, and careers in the biomedical sciences. As we ring in the new year, we bring you our top three posts of 2019. If your favorite is missing, let us know what it is in the comments section below!

Amazing Organisms and the Lessons They Can Teach Us

Two Hawaiian bobtail squid with yellow skin, brown spots, and black eyes catching a neon green reflection. Hawaiian bobtail squid. Credit: Dr. Satoshi Shibata.

Studying research organisms, such as those featured in this post, teaches us about ourselves. These amazing creatures, which have some traits similar to our own, may hold the key to preventing and treating an array of complex diseases.

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Computational Biologist Melissa Wilson on Sex Chromosomes, Gila Monsters, and Career Advice

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Melissa Wilson wearing a floral dress and speaking beside a podium during her lecture. Dr. Melissa Wilson.
Credit: Chia-Chi Charlie Chang.

The X and Y chromosomes, also known as sex chromosomes, differ greatly from each other. But in two regions, they are practically identical, said Melissa Wilson Link to external web site, assistant professor of genomics, evolution, and bioinformatics at Arizona State University.

“We’re interested in studying how the process of evolution shaped the X and the Y chromosome in gene content and expression and how that subsequently affects literally everything else that comes with being a human,” she said at the April 10 NIGMS Director’s Early-Career Investigator (ECI) Lecture at NIH.

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Interview with a Scientist: Jeramiah Smith on the Genomic Antics of an Ancient Vertebrate

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The first known descriptions of cancer come from ancient Egypt more than 3,500 years ago. Early physicians attributed the disease to several factors, including an imbalance in the body’s humoral fluids, trauma, and parasites. Only in the past 50 years or so have we figured out that mutations in critical genes are often the trigger. The sea lamprey, a slimy, snake-like blood sucker, is proving to be an ideal tool for understanding these mutations.

The sea lamprey, often called the jawless fish, is an ancient vertebrate whose ancestor diverged from the other vertebrate lineages (fish, reptiles, birds and mammals) more than 500 million years ago. Jeramiah Smith,Link to external web site associate professor of biology at the University of Kentucky, has discovered that lamprey have two separate genomes: a complete genome specific to their reproductive cells, consisting of 99 chromosomes (humans have 23 pairs) and another genome in which about 20 percent of genes have been deleted after development. Using the lamprey model, Smith and his colleagues have learned that many of these deleted genes—such as those that initiate growth pathways—are similar to human oncogenes (i.e., cancer-causing genes).

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