Boosting your background knowledge

This exercise is a part of Educator Guide: SN 2017 Year in Review / View Guide

Directions: In order to fully appreciate the Top 10 science stories of the year, students have to have some scientific background knowledge. Use this section to help students gain a better understanding of the key vocabulary and concepts in the SN Top 10. To help students better understand some of the vocabulary in these 10 articles, lead a classroom discussion based on the questions that follow.

Alternatively, as an extension of the article-based observation questions, students could work in groups to define and explain key scientific words or phrases from the articles using the questions below as a starting point. Ask students to think beyond the questions below to explain what concepts and key vocabulary must be known in order to understand the article’s content. Working as a group, define the vocabulary in terms of how it relates to the article. Identify scientific topic areas that connect to the article.

Have the groups prepare to present this information to the rest of the class in a creative way. Allow each group to choose how to display and present the information to their classmates — suggest a poster, infographic or another visual that relates all the terms to the central topic. Alternatively, suggest that groups can write a two-minute commercial, skit or story about the article to present to classmates. After each class presentation, let students ask each other questions.

1) Cosmic mysteries unlocked in neutron star collision

Physics and Astronomy: What is a neutron star?

The inward gravitational pull on the mass of a star is normally balanced by the outward pressure generated by fusing hydrogen into helium, which produces energy. After a star has consumed most of its hydrogen and other raw materials, it can no longer generate that outward pressure, and some of its mass is pulled into its core. A star about as large as our sun or smaller will eventually collapse into a white dwarf, the core that remains after the star has blown off its outer layers. A star several times more massive than our sun will collapse until eventually its core is too heavy to withstand its own gravitational force, resulting in an explosion called a supernova. After a supernova, an ultradense, neutron-rich core of a dead star, or a neutron star, remains. Stars much more massive than the sun can collapse even further to form black holes.

Physics and Astronomy: What are gravitational waves?

The dimensions of space and time join into a fabric of the universe called spacetime. In two dimensions, spacetime can be thought of as a rubber sheet. Mass and energy warp spacetime, creating gravitational fields. Acceleration of large masses can create gravitational waves, ripples in the rubber sheet that travel outward at the speed of light.

2) CRISPR gene editing moves into humans, spurs debate

Biological Sciences: What is CRISPR/Cas9?

CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)/Cas9 is a technique for genetically engineering cells or organisms. It has been adapted from a natural system in bacteria that targets and cuts up DNA from invading viruses. For genetic engineering, the Cas9 DNA-cutting enzyme is paired with a guide RNA sequence that corresponds to the desired target DNA sequence. When Cas9 and the guide RNA are introduced into a cell, they can seek out the target DNA and cut it. The cell may repair the DNA with other cellular DNA that it already has, or newly introduced DNA. Using the CRISPR/Cas9 technique, it is possible to delete, add or replace genetic material in a cell.

Biological Sciences: What is genetic discrimination?

Genetic discrimination would be denying people certain rights or opportunities based on their genes. Genetic discrimination can already occur, for example if a health plan will not cover a patient because the insurer knows the patient has a disease-causing mutation. If genetically altering human cells is taken to extremes, there is a danger that society could split into people whose parents had the money and opportunity to correct or even improve their genes, and those whose parents did not.

3) Larsen C ice break invites groundbreaking research

Earth Sciences: What are the Antarctic ice shelves?

Most of Antarctica is ice on top of a solid continent. However, the surface of the ocean adjacent to the continent is frozen, and those regions are called ice shelves since the solid ice protrudes like a shelf over the liquid water. Antarctic ice shelves have different names depending on their locations, and collectively cover approximately 1.5 million square kilometers.

4) Fossils join genetic evidence to revise human origin story

Biological Sciences: What are hominids?

Hominids are humans and their ancestors or relatives in the family of great apes, known as Hominidae. This family includes not only humans but also chimpanzees and gorillas, among others. Human-like hominids split off from other apes in Africa, most recently from a shared ancestor with chimpanzees around 6 million years ago. The genus Homo includes modern humans, Homo sapiens, as well as a number of earlier species and subspecies that have been identified from fossil evidence.

5) Seven Earth-sized planets orbit the same ultracool star

Physics and Astronomy: What are exoplanets?

Exoplanets are planets around stars other than our own sun. Because other stars are so far away and because planets are typically much smaller than stars, do not emit light on their own and do not have much gravity to tug on things exoplanets had been very difficult to detect until recently. Some exoplanets are detected when they cross in front of their star, causing the star’s light as seen from Earth to dim. Other exoplanets have been detected based on the slight gravitational tugs they exert on their star, which causes the star to wobble slightly.

Physics and Astronomy: What is a dwarf star?

A dwarf star is a faint, small star, often a burned-out former star that has used up most of its fuel and collapsed. Other dwarf stars simply had too little matter to become regular stars in the first place. The more mass a star has, the more inward gravitational pull there is, the more pressure and heat are created at the center and the more fusion reactions and energy are produced. A very small star will only produce a small amount of energy, so only planets orbiting very close to it would receive much warmth. On the other hand, smaller stars last much longer than larger stars, since they use up their available fuel more slowly.

Physics and Astronomy: What is a stellar flare?

Stellar flares result from electromagnetic instabilities, in which charged particles at the surface of the star are ejected by changes in the star’s magnetic field. Those charged particles travel through space and can bombard any planets orbiting the star. Earth’s magnetic field shields us from most charged particles emitted by solar flares. Charged particles that follow the magnetic field lines to the North and South poles create the northern and southern lights when they hit the atmosphere. Mars lost its magnetic field long ago, and then its atmosphere was gradually eroded by charged particles from the sun. Planets orbiting near a star prone to flares might have their atmospheres stripped away, killing any life on the surface or preventing it from taking hold in the first place.

6) Quantum communication goes global

Physics and Astronomy: What is quantum entanglement?

Some particles link up as an ethereal pair — across great distances, their characteristics remain interconnected so, for example, the direction of spin of one may be linked to the spin of another. Yet according to quantum physics, particles might have any spin until an observer makes a measurement and determines the direction. If two entangled particles are separated without being measured, and then one particle’s spin is measured, the other’s can be predicted, even though it may now be far away. Einstein called this quantum link “spooky action at a distance.”

Physics and Astronomy: What is quantum teleportation?

Quantum teleportation does not transmit matter from one place to another, but only information. If a sender and receiver each have a pair of entangled particles, for example, the sender can allow his or her entangled particle to interact with another particle he or she wants to “teleport.” The sender can measure the property of interest, which destroys the information stored in that particle. But by sending that measurement to the receiver, the receiver can use the second of the entangled particles and the measurement to replicate the information in the new “teleported” particle.

7) Climate change may silently steal nutrients from crops

Earth Sciences: What is the atmospheric CO2 level?

There is a small but important amount of CO2 in the atmosphere. CO2 is taken up by plants, and produced by animals and decaying plants. Due to the combustion of fossil fuels, the atmospheric CO2 level has increased from approximately 300 parts per million (ppm) to over 400 ppm over the last century. The concentration is rising rapidly and some estimates suggest it could pass 1,000 ppm this century.

Earth Sciences: What is climate change?

Carbon dioxide (and other gases such as methane) act like a greenhouse in the atmosphere. Sunlight of shorter wavelengths enters through the atmosphere, is absorbed by the surface and reemitted as thermal radiation of longer wavelengths. Greenhouse gases prevent this longer radiation from passing back through the atmosphere to return to space, so the Earth gets warmer. As Earth warms, oceans rise from the melting of polar ice and the thermal expansion of liquid water. Other effects of the warming include potentially more intense storm seasons and altered patterns of precipitation.

8) FDA approves gene therapy for two rare blood cancers

Biological Sciences: What is a T cell?

A T cell or T lymphocyte is a type of white blood cell in the immune system. The surface of a T cell is covered with receptors, which sense antigens or surface features on other cells. T cell receptors look for major histocompatibility (MHC) proteins on other cells, a sort of bar code that identifies where the cell is from. T cell receptors also look for pieces of internal cellular proteins that a cell coughs up to its cell surface. If a T cell finds a cell with the wrong MHC bar code or with no MHC bar code, it assumes that cell is an invader (or a transplant), and the T cell initiates an immune response. Likewise, if a T cell finds a cell with pieces of abnormal or unexpected proteins on its surface, it assumes the cell is cancerous or virus-infected and also initiates an immune response. Two major categories of T cells are helper T cells, which respond by producing chemical molecules that egg on other immune cells, and cytotoxic T cells, which respond by trying to kill abnormal cells.

Biological Sciences: What makes a cell a cancer cell?

Unlike normal cells, cancer cells continually divide to produce more copies of themselves proliferating uncontrollably. Successful cancer cells typically: (1) Acquire mutations in their signaling pathways that keep cell division turned on. (2) Acquire mutations that knock out tumor suppressor genes, whose proteins would cause an abnormal cell to either fix its DNA or self-destruct. (3) Use tricks to evade T cells that could detect and kill the cancerous cells.

Biological Sciences: What is a chimeric antigen receptor?

An antigen is a molecule or substance that can trigger an immune response within the body. An antigen receptor is a sensor on the surface of a cell that detects specific antigens. A chimera is unrelated pieces assembled into a whole, like the chimera in Greek mythology. A chimeric antigen receptor is a genetically engineered receptor that contains different pieces; a common example combines pieces of a T cell with an antibody that specifically binds to a protein found on the surface of certain cancer cells. T cells that have been engineered with such a chimeric antigen receptor will recognize and respond to those cancer cells.

9) CTE may be common among pro football players

Biological Sciences: What is tau protein?

Tau proteins are normally associated with cytoskeletal microtubules, which provide internal structure to healthy neurons. In several neurodegenerative diseases such as chronic traumatic encephalopathy, Alzheimer’s disease and Parkinson’s disease, tau proteins tend to clump together. The clumps can damage or kill neurons.

Biological Sciences: What is chronic traumatic encephalopathy?

Chronic traumatic encephalopathy or CTE is a neurodegenerative disease known to affect people who have had repetitive head trauma, including concussions. It has received a lot of media attention in American football players, but it can occur in other athletes prone to head injuries (such as boxers or hockey players), as well as soldiers who have had multiple head injuries. Brains of people with CTE often have clumps of tau proteins, and the disease is associated with memory loss, uncontrolled emotions, depression and dementia.

10) Zika is not gone for good

Biological Sciences: What is Zika virus?

Zika virus is a member of the flavivirus family, which also includes dengue hemorrhagic fever, West Nile virus and yellow fever. Like those other infections, the Zika virus is spread from person to person by mosquitoes. Zika can also be spread by direct sexual contact. Until recently, Zika was believed to generally cause fairly mild symptoms before going away. However, in 2015 and 2016 it became apparent that Zika infection in pregnant women could sometimes cause a baby to be born with an abnormally small head or with other signs of brain damage.

Biological Sciences: What is a viral reservoir?

A reservoir is a source of something: water reservoirs for drinking water or thermal reservoirs for heat. A viral reservoir is a source of viruses, often referring to a place where a virus can hide out before causing future outbreaks in humans. Since viruses need host cells to replicate and survive, animals are good viral reservoirs. Different viruses prefer different types of animals. Primates such as monkeys or apes can be a dangerous reservoir since they are relatively similar to humans, so viruses can more easily hop from monkeys or apes to humans. Bats are another dangerous reservoir of human diseases; even though bats are less closely related to humans, they live in dense colonies and can fly great distances to spread infections.

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