SCIENCE ALLIANCE Gina discovers Genetics, DNA and Characteristics! by Carole Marsh 2008 Carole Marsh Permission is hereby granted to the individual purchaser or classroom teacher to reproduce materials in this book for non-commercial individual or classroom use only. Reproduction of these materials for an entire school or school system is strictly prohibited. Gallopade is proud to be a member of these educational organizations and associations. National Science Teachers Association The National School Supply and Equipment Association The National Council for the Social Studies American Booksellers Association American Library Association Managing Editor: Assistant Editor: Senior Editor: Cover Design: Content Design: Sherry Moss Alfonse Battistelli Janice Baker Vicki DeJoy Vicki DeJoy International Reading Association National Association for Gifted Children Museum Store Association Association of Partners for Public Lands Association of Booksellers for Children Although most of the experiments in this book are regarded as low hazard, author and publisher expressly disclaim all liability for any occurrence, including, but not limited to, damage, injury or death which might arise as consequences of the use of any experiment(s) listed or described here. Therefore, you assume all the liability and use these experiments at your own risk. Author and publisher recommend that all experiments be performed under adult supervision. 1
Gina discovers Genetics, DNA and Characteristics! Table of Contents Science Alliance Intro Page 4 A Word From the Author Page 5 Gina discovers Genetics, DNA and Characteristics! Page 6-7 What are Genes? Page 8 We re Alive! Page 9 Are You Dominant? Page 10-11 It s All about the DNA Page 12-13 High Protein! Page 14 Boys and Girls Page 15 Smart Cells! Page 16 For Better or Worse Page 17 Help Is on the Way Page 18 A Genetic Challenge Page 19 Everybody Wins! Page 20 Tools and Equipment Page 21 Someday, I ll Have a Cool Job! Page 22 Can You Become an Inventor? Page 23 Amazing Discoveries Page 24 The Scientific Method Page 25 Science Fair Project Page 26-27 What Did I Learn? Page 28 Join the Science Alliance Page 29 Metric Conversions Page 30 Glossary Page 31 Answer Key Page 32 3
What are Genes? Scientists have learned a lot more about Mendel s factors. Today scientists call them genes. Genes are what determine your physical traits. These traits include eye color, the shape of your nose, and the color of your hair. Other characteristics, such putting your toys away and making your bed, are behaviors learned from other people. Genes do not determine these kinds of traits. Genes are found on tiny, threadlike structures called chromosomes. Chromosomes are located inside of little units called cells. Some cells look like small circles, while others may be almost square. All living things are made up of cells. Every cell eventually dies. (That s life!) New cells have to be made to replace these cells. This happens through a process called cell division. This is when one cell stretches out, rips in half, and turns into two cells. Think about It! Circle the correct answer to each question below. 1. Genes can determine: a. If you put your toys away after playing with them b. Your eye color c. When you make your bed 2. Chromosomes look like: a. Thick, wooly circles b. Pointed and bubbly squares c. Tiny, threadlike structures 3. Where are genes located? a. Outside of the cell b. On threadlike structures called chromosomes c. Attached to the walls of the cell 4. How do cells replace dead cells? a. By stretching out, dividing, and turning into two cells b. By breaking off into many little pieces and each piece growing into a new cell c. By leaking out water that grows into a new cell 8
We're Alive! You are made up of millions of cells! Cell division keeps us alive and healthy. Nearly all living things undergo cell division such as birds, plants, rabbits, dogs, and humans. Cell division begins in the part of the cell called the nucleus. The nucleus is the brain of the cell. The type of cell division that happens in our body cells is called mitosis. In mitosis, the chromosomes make copies of themselves. Then, after a series of changes, the cell pulls apart and makes two new cells. Each new cell has a new set of chromosomes and its own nucleus. Your cells have 46 chromosomes in 23 pairs. Cell division also occurs in gametes. Gametes are the cells that created you. You got one cell from your father (sperm) and another from your mother (the egg). Gametes are special because they only have 23 chromosomes each. When they combine, they create a cell with 46 chromosomes. That cell keeps on dividing until it turns into a baby. Changes! Perform this activity to see how mitosis occurs. Wow! Materials needed: two colors of modeling clay a sheet of paper a pencil Steps 1 and 2 Instructions: 1. On a piece of paper, draw a large circle to represent a cell. Then draw a line that goes up and down the middle of the cell. 2. Roll modeling clay into two short lines (one of each color). Join them in a V-shape. This represents one set of chromosomes. 3. Line up the chromosomes along the center line of the cell. Repeat Step 2. Place them next to their identical chromosomes on the other side of the line. Step 3 4. Separate the chromosomes by moving them away from the center of the line. Steps 4 and 5 5. Darken the center line to show that your cell has been divided in two. This is mitosis! 9
Are You Dominant? Imagine all your different traits! Freckles, brown eyes, red hair, and dimples all there because of genes! Some of these traits are easily seen, while others are hidden away in our genes, never to be expressed. However, they are still there waiting! We inherit genes in pairs. We get one gene from mom and the other from dad. A dominant gene is strong and has more influence on the offspring. A recessive gene has less influence. The dominant traits show up when just one dominant gene is present. The recessive traits only show up when two recessive genes are present. Red hair Freckles Green eyes It is possible for a person to have one dominant gene and one recessive gene for a particular trait. Take eye color, for example. The gene for brown eyes is dominant. The gene for blue eyes is recessive. If your dad gave you one gene for brown eyes and your mom gave you one gene for blue eyes, you will have brown eyes. The dominant one wins! Dimples Curls Check It Out! Look at your earlobes. Do they dangle freely at the bottom or are they attached tight to your head? Free earlobes are a dominant trait while attached earlobes are a recessive trait. This activity will show you how and why children have different earlobes. Follow the directions below. Materials needed: Note cards and a pen or pencil Instructions: 1. Get 12 blank note cards. Label six of the cards (D) for dominant, and the other six cards (d) for recessive. Write down free earlobes on the (D) cards. Write down attached earlobes on the (d) cards. Each card is a gene. 2. Recruit two boys and two girls that have free dangling earlobes. Recruit one boy and one girl that have attached earlobes. 3. Have the boys with free earlobes pick two cards from a stack of four cards three of the cards in the stack should have a (D) and one of the cards should have a (d). Do the same with the girls that have free earlobes. 4. Give the boy and the girl with the attached earlobes two (d) cards each. All of the kids should have two cards one in each hand. 10