What is a virus, and how does it make you sick?As you work your way through this assignment, look for information to help you answer the following questions:1) What is a cell? 2) What is DNA? 3) How does a virus cause cold and flu symptoms? Page 1 Answer sheet for this lesson (MS Word) (PDF version) Go to Page 2 A virus is a packet of DNA that invades one or more of the cells in your body and takes it over, using the cell to make thousands of identical copies of itself. Here are links to drawings of some of the more common viruses: Image 1 Image 2 Cells. Cells are the tiny building blocks of all plants and animals. Your body is made up of muscle cells, skin cells, blood cells, bone cells, and many others—much like the way this sculpture of Albert Einstein’s face is made up of Legos, only many, many times smaller. How small are they? To get some idea, go to Google and ask “How many cells are in a human body?” 1) Number of cells in the human body: _________________________________________ (Write your answer on your answer sheet.) Now imagine dividing your body up into that many pieces: that’s how small cells are. Cells are made of proteins. Proteins are large, usually very complicated molecules. Here are models of two different protein molecules: Image 3 Image 4 It’s important to remember that, although they look large in the images, protein molecules are still very tiny, since proteins are used to make cells. Another interesting fact is that the shape of a protein often determines how your body uses them. The protein in Image 4, for example, is used by your body to help fight off viruses. The two arms at the top of the protein can hook onto proteins made by viruses and help the body get rid of them. Proteins, the building blocks of cells, are made up of amino acids: the building blocks of building blocks! In the protein models that you just saw, the different colors represent different amino acids. NEXT PAGE BACK TO 5TH GRADE SCIENCE PAGE |