1. Why is the nucleus called the "control center" of the cell? __ 2. What is a gene? __ 3. Where in the cell are chromosomes located? __ 4. DNA can be found in what organelles? __ 5. What two scientists established the structure of DNA? __ 6. Replication is called "semi-conservative" because half of the original strand is __ 7. What are the sides of the DNA ladder made of? __ 8. What three parts make up a single nucleotide: __ 9. What are the 4 bases that make up the rungs of the DNA ladder? __ 10. What sugar is found in DNA? 11. How do the bases bond together? A bónds with __ In RNA? __ 12. Why is RNA necessary to act as a messenger? __ G bonds with __ 13. Proteins are made where in the cell? __ __ 14. How is RNA different from DNA? (list 3 things) 15. The process of copying DNA is called __ 16. What is the shape of DNA? __ __ 17. Proteins are made from what subunits? __ 18. Three bases found on mRNA are called a __ 19. How do some cells become brain cells and others become skin cells, when the DNA in ALL the cells is exactly the same. In other words if the instructions are exactly the same, how does one cell become a brain cell and another a skin cell? 20. Why is DNA called the "Blueprint of Life"?

1. The nucleus is called the "control center" of the cell because it contains the cell's DNA, which carries the genetic instructions for building and operating the cell. It directs all cellular activities.<br /><br />2. A gene is a segment of DNA that codes for a specific protein, which in turn determines a particular trait.<br /><br />3. Chromosomes are located within the nucleus of the cell.<br /><br />4. DNA can be found in the nucleus and mitochondria.<br /><br />5. James Watson and Francis Crick established the double helix structure of DNA, building upon the work of Rosalind Franklin and Maurice Wilkins.<br /><br />6. Replication is called "semi-conservative" because half of the original DNA strand is conserved in each new DNA molecule.<br /><br />7. The sides of the DNA ladder are made of alternating sugar (deoxyribose) and phosphate molecules.<br /><br />8. A single nucleotide is made up of a deoxyribose sugar, a phosphate group, and a nitrogenous base.<br /><br />9. The 4 bases that make up the rungs of the DNA ladder are adenine (A), thymine (T), guanine (G), and cytosine (C).<br /><br />10. Deoxyribose is the sugar found in DNA.<br /><br />11. The bases bond together as follows: A bonds with T, and G bonds with C. In RNA, A bonds with uracil (U), and G bonds with C.<br /><br />12. RNA is necessary to act as a messenger because DNA is too large to leave the nucleus. mRNA carries a copy of the DNA instructions from the nucleus to the ribosomes in the cytoplasm where proteins are made.<br /><br />13. Proteins are made in the ribosomes, which are located in the cytoplasm.<br /><br />14. RNA is different from DNA in three main ways: (1) RNA is single-stranded while DNA is double-stranded. (2) RNA contains the sugar ribose, while DNA contains deoxyribose. (3) RNA contains uracil (U) instead of thymine (T).<br /><br />15. The process of copying DNA is called replication.<br /><br />16. The shape of DNA is a double helix.<br /><br />17. Proteins are made from amino acid subunits.<br /><br />18. Three bases found on mRNA are called a codon.<br /><br />19. Even though all cells in an organism have the same DNA, different genes are active in different cells. This differential gene expression allows cells to specialize. For example, genes that code for brain-specific proteins are active in brain cells, while genes that code for skin-specific proteins are active in skin cells. Various factors, including signals from other cells and the environment, influence which genes are turned on or off in a particular cell.<br /><br />20. DNA is called the "Blueprint of Life" because it contains the genetic instructions for building and maintaining an organism. It carries the hereditary information that is passed down from one generation to the next.<br />