DNA Structure

Week 5 WHOT 3/6 What is the purpose of meiosis (what does it create)? What are the two mechanisms that create variation during meiosis? Turn in: Amoeba Sisters WS

Crossing Over – Independent Assortment –

DNA pretest

Read Pg 176.

DNA Notes All living things are made of the same DNA : Sugar, phosphate, nucleotide (A,C,T,G) Chargoff’s rule: A  T C  G

3/7 Describe and Draw the structure of DNA, label at least 4 nucleotides What are the names of the 4 Nucleotides, (which ones pair with which) What are the other 2 parts of DNA besides nucleotides?

Rosalind Franklin, the real hero? https://www.youtube.com/watch?v=JiME-W58KpU

Epic Rap battles of HISTORRRRREEEEEEYYYYY https://www.youtube.com/watch?v=35FwmiPE9tI

Title: Building a DNA Model pg 180 Components: Cytosine = Blue Phosphates= white tube Thymine = Green Hydrogen bonds= white rod Adenine= Orange Deoxyribose sugar= black pentagon Guanine=Yellow Part 1: Construct Cytosine nucleotides Guanine nucleotides Thymine nucleotides Adenine nucleotides Part 2: Come choose 1 sequence of DNA from the beaker up front. Use your constructed nucleotide to build one side of your DNA ladder. Part 3: Use the base-pairing rules to construct the 2nd side of your DNA ladder. Part 4: Answer the following analysis questions on pg. 181 #1-7 Part 5: Challenge

Watson and Crick Paper Notes DNA is (-) charged Each strand of DNA has direction (5’ to 3’) 3 parts of DNA Base pairs (A & T, C & G) Deoxyribose (sugar) Phosphate backbone 2 strands are hydrogen bonded.

3/1 In your journal, Do journal write about the structure of DNA, be sure to include Shape (double helix) Charge Structure (what its made of.) Should be ~1/2 page.

Title: Structure of DNA Notes INB Pg. 76 D: Deoxyribose (sugar) N: Nucleic A: Acid -Found in all cells (in the nucleus) -A portion of DNA codes for a protein is called a gene. (lets draw it!) -DNA Structure 1. shape: double helix, twisted ladder 2. made of units called nucleotides (sugar, phosphate, & bases) 3. Arrangement: sugar + phosphate= backbone 4. Nitrogen bases (A, G, C, T) = rungs of ladder -Base pairing 1. A with T, C with G 2. bonded by weak hydrogen bonds (Good to be weak! DNA needs to be pulled a part) 3. base pairing creates COMPLEMENTARY strands

3/8 If a piece of DNA had the following sequence, what would be its complimentary strand? AATTCCGGATCG You ran an assay on the DNA of an African Swallow, it was found to have 30% of its DNA was Thymine, what were the % of the other nitrogenous bases?

Answer Key 1.DNA is made up of sugar, phosphates and nitrogen bases. The base letters (A, T, C and G) represent the kind of nitrogen base. 2. The structure of the backbone and the types of nitrogen bases are constant, the way the bases pair are also constant. BUT the order of the base pairs can vary. 3. The order of the nucleotides will determine the information used to code for each gene. Each sequence is unique to the variation of each gene you possess. 4. Write your 2 stranded DNA sequence (student answers will vary) 5. If 27% of the bases in a certain segment of DNA were adenine, then thymine would be 27% and cytosine and guanine would each be 23%. (all add up to 100%) 6. Organisms contain millions/billions of base pairs, which allows for a large number of ways to arrange the 4 bases, this large arrangement creates an extensive code. 7. They might differ in the total amount of base pairs and sequence of base pairs. A mouse, bacteria and human will contain a different variation of DNA sequence and overall amount of DNA. (Humans, mice, and bacteria have different traits! But, do we have some similar traits? Is some of our DNA similar?)

DNA Discovery “Big Playa’s” Watson & Crick Rosalind Franklin Maurice Wilkins Erwin Chargaff

“It has not escaped our notice” That the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.

DNA Replication, How? DNA replicated Semi-conservatively.

3/9 Planet Earth II

3/10 Make-up Day: Happy Trees – pg 181 Q1-7 Earth stamp – DNA Extraction Lab