Please take out your lab book and prepare for a warm-up! Biology 1/18 and 1/19 Please take out your lab book and prepare for a warm-up!

Warm-Up 1/18 and 1/19 Last class you extracted DNA from a strawberry. If I extracted YOUR DNA, would it look the same or different? Why?

DNA Structure

DNA’s Job DNA carries information from one generation to the next (parent to child) Every cell in your body has the same 46 chromosomes of DNA DNA determines how you look by making proteins Most of these proteins are enzymes, which are the tools that build your body

Structure of DNA Long molecule made of nucleotides Every nucleotide has three parts: 5 carbon sugar Phosphate group Base (contains Nitrogen)

Structure of DNA Nucleotides link to form strands of DNA Nucleotides have the same sugar and phosphate There are four different bases: adenine (A), guanine (G), cytosine (C), thymine (T)

Nucleotide Practice Phosphate Following this example, draw the four different types of nucleotides found in DNA Hint: the only difference between them is the letter! Adenine (A) Sugar

How do Nucleotides Fit Together? Sugar and phosphate make up the backbone; bases are protected in the middle DNA strands have a 5’ end, which starts with a phosphate, and a 3’ end, which ends with a sugar DNA is always built in the 5’ to 3’ direction!

How Bases Pair Up A and T always pair up; G and C always pair up Chargaff’s Rule: The percentages of A and T are the same within a DNA molecule; so are G and C! All organisms follow this rule: [A] = [T] and [G] = [C]

Percentage of Bases in Organisms Streptococcus 29.8 31.6 20.5 18.0 Yeast 31.3 32.9 18.7 17.1 Herring 27.8 27.5 22.2 22.6 Human 30.9 29.4 19.9 19.8

The Double Helix DNA is made of two complementary strands The strands are wound in a double helix The strands are held together by hydrogen bonds Hydrogen bonds result from attractions between H, N, and O on the bases

The Double Helix

DNA Pioneers James Watson (US) and Francis Crick (UK) created the first model of the double helix in 1953 They deduced the structure using information from Rosalind Franklin, who created an x-ray photograph of it Franklin passed away before receiving the Nobel Prize, but it was awarded to Watson and Crick

two nucleotides for you! Self Test!!! Draw one strand of DNA with the sequence AGTACG. Then, draw in the other strand, pairing A with T and G with C I drew the first two nucleotides for you!

It looked just like this, right? Now label the 5’ and 3’ ends of each strand!

Final Exam Info. Period 4: Wed.,1/24 Period 5,6,7:Thurs.,1/25 Worth 1.5 Unit Tests Open Notebook All notes must be hand-written! 50 Multiple Choice ALL MISSING WORK DUE WITH FINAL! Topics: Chapter 13: Plate Tectonics Chapter 6: Evolution Chapter 7: Genetics Chapter 8: Structure and Function of macromolecules

Today’s Task Find the major concepts from Chapters 6 and 13 in your lab book Add info, if needed. Highlight!