1. Searching for the “Secret of Life” 1.What is the fundamental unit of all living things? The cell 2.Which cellular structure controls the cell and carries the hereditary information? The nucleus 3.What molecule in the nucleus carries the code of life? DNA 1.What is the fundamental unit of all living things? The cell 2.Which cellular structure controls the cell and carries the hereditary information? The nucleus 3.What molecule in the nucleus carries the code of life? DNA

2. Nucleic Acids I.DNA A.Background Info 1.DNA is stored in the _______ of a cell 2.DNA is the basic substance of heredity.  Heredity is the passing of traits from parent to offspring (baby).  Traits are your physical characteristics (eye, skin and hair color, height, etc) 3.DNA is a molecule that stores and passes on genetic information (traits) from one generation to the next  It is why you look like your parents!

3. B.Structure 1.DNA is made of repeating units called nucleotides. 2.Nucleotides have 3 parts: a.A nitrogen containing base b.A 5-carbon sugar called deoxyribose c.A phosphate molecule What do you think DNA stands for? DeoxyriboNucleic Acid

4. Phosphate group Deoxyribose Nitrogen-containing base NUCLEOTIDE (Draw Me!)

5. 3.DNA has 4 different nucleotide bases. a.Adenine (A) b.Cytosine (C) c.Guanine (G) d.Thymine (T) AdenineGuanine CytosineThymine Phosphate group Deoxyribose

6. C.DNA Discovery 1.Mid-1800s: scientists knew the nucleus contained a nucleic acid molecule 2.By 1950, scientists knew what DNA was made of, but didn’t know what it looked like until… 3.1952, a woman named Rosalyn Franklin took the first pictures of DNA using X-ray diffraction 4.Using the work of Franklin, James Watson and Francis Crick made a model of DNA… THE DOUBLE HELIX!

7. D.The Double Helix 1.The overall shape of DNA is described as a double helix (a twisted ladder) a.The “rails” of the ladder are made of deoxyribose and phosphate molecules. b.The “rungs” of the ladder are made of the bases A, C, G, T.

8. 2.A simple model of DNA What holds the bases together to make the “rungs” of the ladder? What holds the deoxyribose and phosphate molecules together to make the “rails” of the ladder?

9. E.Principles of Base Pairing (Chargaff’s Rule) A.The opposing bases always pair the same:  Adenine (A) pairs with Thymine (T)  Guanine (G) pairs with Cytosine (C) What would be the complementary base sequence for the strand of DNA below? A C G G T T A C A A T G A TGC C AAT G T TAC T

10. II.How does DNA control living organisms? A.DNA contains the instructions to make proteins. What is so important about proteins? 1.Made of 20 different amino acids 2.Control many reactions in living organisms 3.Used for growth and repair of cells 4.Make hormones, enzymes and toxins 5.Make you, YOU! B.A section of DNA that has the instructions to make a specific protein is called a gene

11. III. RNA: The Other Nucleic Acid What does RNA stand for? Ribonucleic Acid  Differences between DNA and RNA 1.RNA contains the sugar ribose instead of deoxyribose. 2.RNA is found in both the nucleus and cytoplasm. DNA is only in the nucleus. 3.RNA contains uracil (U) instead of thymine (T)

12. B. Three Kinds of RNA 1.Messenger RNA (mRNA) a.Copies the DNA code in the nucleus and carries the message to the ribosomes

13. 2.Transfer RNA (tRNA) a.It transfers amino acids to the ribosome and places them in the correct position in the protein. 2.Transfer RNA (tRNA) a.It transfers amino acids to the ribosome and places them in the correct position in the protein. 3. Ribosomal RNA (r-RNA) a. Part of the ribosome that is involved in making tRNA

14. IV. Protein Synthesis Summary (Steps to make a protein) 1.Instructions to make proteins gets copied from DNA to mRNA. 2.The mRNA molecule leaves the nucleus and goes to a ribosome. 3.tRNA brings amino acids to the ribosome where they are joined together to make a protein using the instructions on the mRNA molecule.

15. V. Mutations  Mutation is any change in the DNA  Mutations can happen when: a.Chromosomes are copied b.Nondisjunction (chromosomes go the wrong way in meiosis) c.Exposure to chemicals, X-rays, sunlight 3.Mutations can cause the wrong protein to be made, which usually kills the organism or…