Objectives: Describe the overall structure of DNA Do Now Take out your vocabulary and outline homework for 11.1 What organelle is known as the “control center” of the cell? nucleus What structures are found in the nucleus? chromosomes What are located on chromosomes? Genes What are chromosomes composed of? DNA wound around proteins Homework: 11.1 Genes and DNA Reinforcement Guide Objectives: Describe the overall structure of DNA

Objectives: Describe the overall structure of DNA Chapter 11 Section 1 Objectives: Describe the overall structure of DNA

What do the following have in common? Mitochondria Humans Frogs Objectives: Describe the overall structure of DNA

Objectives: Describe the overall structure of DNA They all contain DNA! Objectives: Describe the overall structure of DNA

Objectives: Describe the overall structure of DNA DNA Fun Facts!!! Did You Know?: Each one of your cells contains about 2-3 meters (8-10 feet) of DNA! If you unraveled the DNA from all of your cells, it would stretch to the moon over 300,000 times! Objectives: Describe the overall structure of DNA

Objectives: Describe the overall structure of DNA What Does DNA Do? DNA contains the genetic information for our cells. Our DNA tells our cells what proteins to make. The proteins determine how the cell functions. So DNA ultimately controls all cellular functions. Objectives: Describe the overall structure of DNA

Deoxyribonucleic Acid The monomers of DNA are nucleotides. Each nucleotide has three parts: Draw this nucleotide in your notes!! 1. Phosphate 2. Sugar (Deoxyribose) Phosphate 3. Nitrogen Base Sugar Nitrogen Base The nucleotides are put together during DEHYDRATION SYNTHESIS reactions.

Objectives: Describe the overall structure of DNA Nitrogen Bases There are two different types of bases: Purines (2 rings) – Adenine and Guanine Pyrimidines (1 ring) – Thymine and Cytosine Objectives: Describe the overall structure of DNA

Objectives: Describe the overall structure of DNA Double Helix DNA looks like a twisted ladder. It is composed of two strands of nucleotides bonded together. The sides of the ladder are made of alternating sugars and phosphates. The “rungs” of the ladder are made of nitrogen bases. Objectives: Describe the overall structure of DNA

Objectives: Describe the overall structure of DNA The Double Helix Objectives: Describe the overall structure of DNA

How do we know about DNA’s shape? The double helix is the model proposed by scientists James Watson and Francis Crick in 1953. They received a Nobel Prize in 1962 for their discovery Watson and Crick’s model was supported by evidence from other scientists like Rosalind Franklin and Maurice Wilkins who studied X-ray photographs of DNA. Objectives: Describe the overall structure of DNA

Bonding Patterns The sugar-phosphate backbone is held together with strong covalent bonds. The nitrogen bases are held together by weak hydrogen bonds. The nitrogen bases bond in specific ways according to the Complementary Base Pairing Rule. A & T will only bond together. They form 2 H bonds. C & G will only bond together. They form 3 H bonds. The sequence of bases on one strand, will complement the sequence of bases on the other.

So ALWAYS REMEMBER… 1. Adenine ALWAYS bonds with Thymine A-T 2. Cytosine ALWAYS bonds with Guanine C-G Objectives: Describe the overall structure of DNA

Objectives: Describe the overall structure of DNA So… IF we have a strand of DNA with the following code: A T G G A A T C G A T THEN, the sequence of the complementary strand will be… T A C C T T A G C T A Objectives: Describe the overall structure of DNA

Objectives: Describe the overall structure of DNA Activity time! On a blank piece of computer paper your are going to draw a small segment of DNA! Sugars – Red Adenine - Purple Phosphates – Black Thymine - Pink Guanine – Green Cytosine – Blue The segment of DNA going down the length of the left side of the paper will be as follows: A – G – C – A – A – T – C - G Objectives: Describe the overall structure of DNA