跟讀練習: What is DNA and How Does it Work? - 通過影片學習英語口語

Stated Clearly presents: what is DNA and how does it work DNA also known as deoxyribonucleic acid is a molecule it's a bunch of atoms stuck together In the case of DNA, these adoms combined to form the shape of a long spiraling ladder sort of like this one here if you ever studied biology or watched the movie Jurassic Park, you probably heard that DNA acts as a blueprint or recipe for living thing but how?

how on earth can a mere molecule act as a blueprint for something as complex and wonderful as a tree a dog or a dinosaur Yelp!

to help answer that question let's first take a quick look at amino acids amino acids are tiny little chemicals inside our bodies that are so important they're often referred to as the building blocks of life there's about twenty different kinds each with their own unique shape the cool thing about them is they can be attached to each other kind of like Legos to produce an endless variety of larger particles particles called proteins amino acids make up proteins proteins along with other chemicals combined to form living cells cells make up tissues tissues make up organs and organs when they're all put together and functioning of course combined to form living creatures like you and me these proteins that make up our bodies and keep in mind there's millions of different kinds of proteins they each have to be formed in the perfect shape in order to function if they are the wrong shape they usually won't work that's where DNA comes in DNA does a lot of interesting things some of which we don't fully understand but one of its main and most well understood functions is to tell amino acids how to line up and form themselves into the perfect protein shapes in theory if the right proteins are built at the right time and in the right place everything else from cells to organs to entire creatures will come out just fine this here is a simplified model of DNA it shows us that the steps of the ladder are made up of four different kinds of chemicals shown here by different colors and letters if you look at just one half of the molecule you can read this chemical sequence or genetic code from top to bottom sort of like a book a single strand of DNA is extremely long millions of letters long it spends most of its life coiled up like a noodle living inside the nucleus or the centerpiece of a cell amino acids however live outside the nucleus in what's called the cytoplasm to help DNA interact with the cytoplasm and convert those amino acids into proteins special chemicals inside the nucleus make partial copies of the DNA code these partial copies called RNA look a lot like DNA but they're shorter of course and they're missing one of their sides their small shape and size allows them to fit through tiny pores in the nucleus out to the cytoplasm and into the mouth of another particle called a ribosome ribosomes are protein building machines they the RNA code three letters at a time suck amino acids out of their surroundings stick them together in a chain according to the genetic code as a chain grows it bends, folds, and sticks to itself to form a perfectly shaped protein every three letters of the RNA code tell the ribosome which of the twenty different kinds of amino acids should be added next for example CAA tells the ribosome to grab a glutamine AGU tells it to grab a serine and so on once a protein is built it then goes on to do a number of different things, one of which could be to help form of brand new cell so to answer the original question what is DNA?

DNA is a molecular blueprint for a living thing how does it work?

DNA creates RNA RNA creates protein proteins go on to form life this entire process as complicated, sophisticated and magical as it might seem is entirely based in chemistry it can be studied it can be understood i'm Jon Perry and that's DNA Stated Clearly thanks for watching share with friends on facebook or twitter or where ever subscribe to us if you have any questions or comments you can post those in the comments section Learn more about DNA at StatedClearly.com www.StatedClearly.com til next time stay curious