1. DNA: the code of life

2. A. DNA  Contains the genetic information for cells to make proteins. 1)Proteins determine a variety of traits, from hair color to an organism’s ability to digest food.

3. 2)It took almost 100 years after the discovery of DNA for scientists to figure out it looked like a twisted ladder (also known as a double helix). A. DNA

4. 3)James Watson and Francis Crick made the first accurate model of DNA in 1953. A. DNA

5. 4)The sides of the ladder are made up of sugar- phosphate molecules. 5)The rungs of the ladder are made up of nitrogen bases (molecules that contain nitrogen and other elements.) A. DNA

6. 6)There are 4 nitrogen bases that make the rungs (steps) of the ladder in DNA: - Adenine - Adenine always bonds always bonds to Thymine to Thymine - Guanine - Guanine always bonds always bonds to Cytosine to Cytosine A. DNA

7. 7)Before a cell divides, its DNA duplicates itself by unwinding and separating its sides, then forming new sides. A. DNA

8.  A section of a DNA molecule that contains the information to code for one specific protein. B. GENES

9. 1)A gene is made up of a series of bases in a row arranged in a specific order. EXAMPLE: EXAMPLE: CAGTATAGGTAACTG CAGTATAGGTAACTG 2)Each gene is located at a specific place on a chromosome. B. GENES

10. 3)A gene contains the code that determines the structure of DNA. 4)The order of the nitrogen bases along a gene forms a genetic code that specifies what type of protein will be produced. B. GENES

11.  Made up of molecules called amino acids. 1)Amino acids are compounds made in the body which combine to form proteins. C. proteins

12. 2)RNA (ribonucleic acid) carries the genetic code from the DNA inside the nucleus to the ribosomes in the cytoplasm of the cell. C. proteins 3) There are 4 nitrogen bases that make the bases that make the rungs (steps) of the rungs (steps) of the ladder in RNA: ladder in RNA: - Adenine always bonds - Adenine always bonds to Uracil to Uracil - Guanine always bonds - Guanine always bonds to Cytosine to Cytosine

13.  Three types: Messenger RNA (mRNA)Messenger RNA (mRNA) Ribosomal RNA (rRNA)Ribosomal RNA (rRNA) Transfer RNA (tRNA)Transfer RNA (tRNA) RNA

14. I.Messenger RNA (mRNA) – copies the message (code) from DNA in the nucleus and carries the code to the ribosomes in the cytoplasm. copies the message (code) from DNA in the nucleus and carries the code to the ribosomes in the cytoplasm. RNA

15. II.Ribosomal RNA (rRNA) – makes up the ribosomes where the proteins are built. makes up the ribosomes where the proteins are built. RNA

16. III.Transfer RNA (tRNA) – brings amino acids to the ribosomes to build the proteins. brings amino acids to the ribosomes to build the proteins. RNA

17. DNA vs. RNA DNARNA double stranded single stranded has Thymine has Uracil sugar = deoxyribose sugar = ribose NEVER leaves the nucleus leaves the nucleus

19.  Any permanent change in the DNA sequence of a gene or chromosome. D. Mutations 1)Can be caused by outside factors like x-rays, sunlight, and some chemicals.

20. 2)Mutations can cause the cell to reproduce an incorrect protein during protein synthesis. 3)During DNA replication, a base pair may be added, a base pair may be substituted for another, or one or more bases may be deleted from a section of DNA. D. Mutations

21. 4)Mutations may also occur when chromosomes don’t separate correctly during the formation of sex cells. This results in changes in the traits of an organism. D. Mutations