Tag: DNA

Quiz: Are You a Genetics Genius?

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Genes are segments of DNA. They contain instructions for building one or more molecules that help the body work. Researchers in the field of genetics study genes and heredity—how certain traits are passed from parents to their offspring through DNA. NIGMS supports many scientists who investigate the genetics of people and research organisms to better understand human health and disease.

Take our quiz below to test how much you know about genetics. Then check out our new fact sheet on genetics to learn more. For more quizzes and other fun learning tools, visit our activities and multimedia webpage.

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Gone Fishing: Teaching Bioinformatics With Skate DNA

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As computers have advanced over the past few decades, researchers have been able to work with larger and more complex datasets than ever before. The science of using computers to investigate biological data is called bioinformatics, and it’s helping scientists make important discoveries, such as finding versions of genes that affect a person’s risk for developing various types of cancer. Many scientists believe that almost all biologists will use bioinformatics to some degree in the future.

A cluster of various-sized dots connected by glowing lines.
Bioinformatics software was used to create this representation of a biological network. Credit: Benjamin King, University of Maine.

However, bioinformatics isn’t always included in college biology programs, and many of today’s researchers received their training before bioinformatics was widely taught. To address these gaps, the bioinformatics cores of the five Northeast IDeA Networks of Biomedical Research Excellence (INBREs)—located in Maine, Rhode Island, Delaware, Vermont, and New Hampshire—have worked together to offer basic bioinformatics training to students and researchers. The collaboration started in 2009 with a project where researchers sequenced the genome of a fish called the little skate (Leucoraja erinacea) and used the data to develop trainings.

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An Enlightening Protein

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A fly glowing green. A fruit fly expressing GFP. Credit: Jay Hirsh, University of Virginia.

During the holiday season, twinkling lights are a common sight. But no matter what time of the year, you can see colorful glows in many biology labs. Scientists have enabled many organisms to light up in the dark—from cells to fruit flies and Mexican salamanders. These glowing organisms help researchers better understand basic cell processes because their DNA has been edited to express molecules such as green fluorescent protein.

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Q&A With Nobel Laureate and CRISPR Scientist Jennifer Doudna

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A headshot of Dr. Doudna. Jennifer Doudna, Ph.D. Credit: University of California, Berkeley.

The 2020 Nobel Prize in Chemistry was awarded to Jennifer Doudna, Ph.D., and Emmanuelle Charpentier, Ph.D., for the development of the gene-editing tool CRISPR. Dr. Doudna shared her thoughts on the award and answered questions about CRISPR in a live chat with NIH Director Francis S. Collins, M.D., Ph.D. Here are a few highlights from the interview.

Q: How did you find out that you won the Nobel Prize?

A: It’s a little bit of an embarrassing story. I slept through a very important phone call and finally woke up when a reporter called me. I was just coming out of a deep sleep, and the reporter was asking, “What do you think about the Nobel?” And I said, “I don’t know anything about it. Who won it?” I thought they were asking for comments on somebody else who won it. And she said, “Oh my gosh! You don’t know! You won it!”

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Scientist Interview: Investigating Circadian Rhythms with Michael W. Young

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Sudden changes to our schedules, like the end of daylight saving time this Sunday or flying across time zones, often leave us feeling off kilter because they disrupt our bodies’ circadian rhythms. Circadian rhythms are physical, mental, and behavioral changes that follow a daily cycle. When these “biological clocks” are disrupted, our bodies eventually readjust. However, some people have conditions that cause their circadian rhythms to be permanently out of sync with their surroundings.

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Phosphorus: Glowing, Flammable, and Essential to Our Cells

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Of the 118 known elements, scientists believe that 25 are essential for human biology. Four of these (hydrogen, oxygen, nitrogen, and carbon) make up a whopping 96 percent of our bodies. The other 21 elements, though needed in smaller quantities, perform fascinating and vital functions. Phosphorus is one such element. It has diverse uses outside of biology. For example, it can fuel festive Fourth of July fireworks! Inside our bodies, it’s crucial for a wide range of cell functions.

A graphic showing phosphorus’s abbreviation, atomic number, and atomic weight connected by lines to illustrations of DNA helixes, a match, and a glowing white pyramid. Phosphorus plays a vital role in life as part of DNA’s backbone. Red phosphorus helps ignite matches, and white phosphorus glows in the presence of oxygen. Credit: Compound Interest.
CC BY-NC-ND 4.0 Link to external web site. Click to enlarge
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RNA Polymerase: A Target for New Antibiotic Drugs?

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DNA, with its double-helix shape, is the stuff of genes. But genes themselves are only “recipes” for protein molecules, which are molecules that do the real heavy lifting (or do much of the work) inside cells.

RNAP illustrated as a crab claw, clamping on a DNA double helix. Artist interpretation of RNAP grasping and unwinding a DNA double helix. Credit: Wei Lin and Richard H. Ebright.

Here’s how it works. A molecular machine called RNA polymerase (RNAP) travels along DNA to find a place where a gene begins. RNAP uses a crab-claw-like structure to grasp and unwind the DNA double helix at that spot. RNAP then copies (“transcribes”) the gene into messenger RNA (mRNA), a molecule similar to DNA.

The mRNA molecule travels to one of the cell’s many protein-making factories (ribosomes), which use the mRNA message as instructions for making a specific protein.

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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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The Skull’s Petrous Bone and the Rise of Ancient Human DNA: Q & A with Genetic Archaeologist David Reich

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A macro image of the petrous bone. 3 sections are color coded A (green), B (blue), and C (red)The human petrous bone in the skull protects the inner ear structures. Though it is one of the hardest, densest bones in the body, some portions (such as the area in orange, protecting the cochlea) are denser than others. Possibly because the petrous bone is so dense, DNA within the petrous bone is better preserved than in other bones. In some cases, scientists have extracted more than 100 times more DNA from the petrous bone than other bones, including teeth. Credit: Pinhasi et al., 2015, PLOS ONE.

For the past few decades, new evidence about ancient humans—in the form of skeletal remains, tools, and other artifacts—has trickled in, inching us closer to an understanding of how our species evolved and spread out across the planet. In just the past few years, however, knowledge of our deep past expanded significantly thanks to a series of technological breakthroughs in sequencing of ancient human genomes. This technology can be used to find genetic links among populations of human ancestors dating back hundreds of thousands of years.

In addition to advances in genomic technology, another factor is driving the explosion of new discoveries—an inch-long section of the human skull. Found near our ears, this pyramid-shaped portion of the temporal bone is nicknamed the petrous bone. The bone is very hard, possibly because it needs to protect fragile structures such as the cochlea, which translates sound into brain signals, and the semicircular canals, which help us maintain our balance. Perhaps because the petrous bone is so dense, it also is the bone in the body that best preserves DNA after a person dies. As a result, archaeologists are scrambling to study samples taken from this pyramid-shaped structure to unlock the mysteries of our species’ formative years.

Here’s a sampling of headlines declaring new findings about ancient peoples from around the globe that were based on genetic information obtained from the petrous bone (NIGMS-funded research indicated in black):

“How the introduction of farming changed the human genome” November 2015

“Fourth strand’ of European ancestry originated with hunter-gatherers isolated by Ice Age” November 2015

“Scientists sequence first ancient Irish human genomes” December 2015

“Genetic studies provide insight into ancient Britain’s diversity” January 2016

“The world’s first farmers were surprisingly diverse” June 2016

“Study reveals Asian ancestry of Pacific islanders” October 2016

“Ancient DNA solves mystery of the Canaanites, reveals the biblical people’s fate” July 2017

“Ancient DNA data fills in thousands of years of human prehistory in Africa” September 2017

“European Hunter-Gatherers Interbred With Farmers From the Near East” November 2017

“Surprise as DNA reveals new group of Native Americans: the ancient Beringians” January 2018

“Ancient DNA reveals genetic replacement despite language continuity in the South Pacific” February 2018

“Stone Age Moroccan Genomes Reveal Sub-Saharan African, Near Eastern Ancestry” March 2018

“Some early modern populations in Britain may have had dark skin” March 2018

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Genomic Gymnastics of a Single-Celled Ciliate and How It Relates to Humans

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Laura Landweber
Credit: Denise Applewhite.
Laura Landweber
Grew up in: Princeton, New Jersey
Job site: Columbia University, New York City
Favorite food: Dark chocolate and dark leafy greens
Favorite music: 1940’s style big band jazz
Favorite hobby: Swing dancing
If I weren’t a scientist I would be a: Chocolatier (see “Experiments in Chocolate” sidebar at bottom of story)

One day last fall, molecular biologist Laura Landweber Link to external web site surveyed the Princeton University lab where she’d worked for 22 years. She and her team members had spent many hours that day laboriously affixing yellow Post-it notes to the laboratory equipment—microscopes, centrifuges, computers—they would bring with them to Columbia University, where Landweber had just been appointed full professor. Each Post-it specified the machinery’s location in the new lab. Items that would be left behind—glassware, chemical solutions, furniture, office supplies—were left unlabeled.

As Landweber viewed the lab, decorated with a field of sunny squares, her thoughts turned to another sorting process—the one used by her primary research subject, a microscopic organism, to sift through excess DNA following mating. Rather than using Post-it notes, the creature, a type of single-celled organism called a ciliate, uses small pieces of RNA to tag which bits of genetic material to keep and which to toss.

Landweber is particularly fond of Oxytricha trifallax, a ciliate with relatives that live in soil, ponds and oceans all over the world. The kidney-shaped cell is covered with hair-like projections called cilia that help it move around and devour bacteria and algae. Oxytricha is not only bizarre in appearance, it’s also genetically creative.

Unlike humans, whose cells are programmed to die rather than pass on genomic errors, Oxytricha cells appear to delight in genomic chaos. During sexual reproduction, the ciliate shatters the DNA in one of its two nuclei into hundreds of thousands of pieces, descrambles the DNA letters, throws most away, then recombines the rest to create a new genome.

Landweber has set out to understand how—and possibly why—Oxytricha performs these unusual genomic acrobatics. Ultimately, she hopes that learning how Oxytricha rearranges its genome can illuminate some of the events that go awry during cancer, a disease in which the genome often suffers significant reorganization and damage.

Oxytricha’s Unique Features

Oxytricha carries two separate nuclei—a macronucleus and a micronucleus. The macronucleus, by far the larger of the two, functions like a typical genome, the source of gene transcription for proteins. The tiny micronucleus only sees action occasionally, when Oxytricha reproduces sexually.

Oxytricha trifallax cells in the process of mating
Two Oxytricha trifallax cells in the process of mating. Credit, Robert Hammersmith.

What really makes Oxytricha stand out is what it does with its DNA during the rare occasions that it has sex. When food is readily available, Oxytricha procreates without a partner, like a plant grown from a cutting. But when food is scarce, or the cell is stressed, it seeks a mate. When two Oxytricha cells mate, the micronuclear genomes in each cell swap DNA, then replicate. One copy of the new hybrid micronucleus remains intact, while the other breaks its DNA into hundreds of thousands of pieces, some of which are tagged, recombined, then copied another thousand-fold to form a new macronucleus. Continue reading “Genomic Gymnastics of a Single-Celled Ciliate and How It Relates to Humans”