DNA - Structure and Function
AIM:
What is DNA? What is it made of? Can I match base pairs? What is the difference between DNA and chromosomes? Lesson Questions: a. Where are my genes? b. How is DNA like a puzzle? c. What is the difference between DNA, genes and chromosomes? d. What is the relationship between genes and traits?
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The video above is an entertaining song about what this reading will cover.
Reading guide
REMEMBER LINKS that are BOLD & UNDERLINED are required for you click. Other links are optional. |
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Introduction
We all know that children tend to resemble their parents in appearance. Parents and children generally have similar eye color, hair texture, height and other characteristics because children inherit genes that control specific characteristics from their parents. The slideshow on your right shows pictures of two relatives split and half and combined as one. Can you see the family resemblance? |
Where Are My Genes?
In past units you have learned about the cells and its organelles. If you need a review about cells watch this video. Inside the center of each cell there is the nucleus. The nucleus is nicknamed the "boss" because it contains genetic material or DNA (deoxyribonucleic acid). The DNA contains all the information and instructions needed to make an organism. All living things contain genetic material. This means that a banana, human, goldfish, and even an ameba contain DNA! |
The image below shows how DNA base pairs fit together like a puzzle piece.
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How is DNA Like a Puzzle?
DNA is shaped like a twisted latter. The two sides of the latter are made up sugars (dioxyribose) and phosphates. The steps of the latter are made up of matching nucleotides or base pairs: adenine (A), thymine (T), guanine (G), and cytosine (C). If the DNA were really a set of written instructions the base pairs would be the letters. DNA is like a puzzle because the base pairs can only fit together in certain way. A pairs with T and C pairs with G. Look at the picture on the left. You can see that green (A) matches red (T) and yellow (C) matches pink (G). Try this activity for five minutes to see if you can match the base pairs correctly. OK, and we are back! That was working goal #2 that you just completed. You can check that off in your logbook now. Hopefully, by doing that activity you learned how to match base pairs and that the molecule is very long. In fact if you were |
What is the Difference Between DNA, Genes and Chromosomes?
DNA is a very long molecule. If you were to take one strand of DNA from one cell it would be over six feet long.
You have about 10 trillion (1.0 x 10^13) cells in your body, so if you stretched the DNA in all the cells out, end to end, they'd stretch over 744 million miles. That means that your DNA could stretch to the moon and back alomst 1500 times and your DNA would reach there and back about 4 times!
DNA is a very long molecule. If you were to take one strand of DNA from one cell it would be over six feet long.
You have about 10 trillion (1.0 x 10^13) cells in your body, so if you stretched the DNA in all the cells out, end to end, they'd stretch over 744 million miles. That means that your DNA could stretch to the moon and back alomst 1500 times and your DNA would reach there and back about 4 times!
Right now you are probably wondering: "How does such a long molecule fit inside my microscopic nucleus?"
The DNA is packaged and organized into chromosomes. Chromosomes are tightly wound DNA molecules packaged into strands. Watch this video to see how they are tightly packed together. In other words chromosomes is DNA that is wound up like a long spool of yarn. As you can see the picture on the top left shows the chromosomes in the nucleus of the cell and the DNA unwinding from the chromosomes. Genes are specific parts of the DNA that code for a specific trait. Genes are found on specific spot on a chromosome. The figure to the left the bands on the "cartoon" chromosome. These bands represent where a particular gene can be found. Watch the video below before you continue. |
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What is the relationship between genes and traits?
Genes are specific parts of DNA and chromosomes that code for a particular trait. The gene is a part of DNA. It is literally a piece of a molecule. However, genes are instructions that are expressed. This means that the directions in the genes become actions that create a trait. Traits inherited characteristics that can be observed. Their are inherited traits that come from our genes and learned traits that we acquire through experiences. Watch this video for examples of inherited and learned traits.
Genes are specific parts of DNA and chromosomes that code for a particular trait. The gene is a part of DNA. It is literally a piece of a molecule. However, genes are instructions that are expressed. This means that the directions in the genes become actions that create a trait. Traits inherited characteristics that can be observed. Their are inherited traits that come from our genes and learned traits that we acquire through experiences. Watch this video for examples of inherited and learned traits.
Check for Understanding
In your notebooks answer the following questions. a. Where are my genes? b. How is DNA like a puzzle? c. What is the difference between DNA, genes and chromosomes? d. What is the relationship between genes and traits? |
What do I do next?
4. Complete the Tour of the Basics Tutorial and the Tour of the Basics Survey. Due Monday 10/28. |