Let’s Review! What is a macromolecule? What are the four kinds of organic molecules? What are nucleic acids made of? - A large organic molecule (made of carbon!) - Carbohydrates, lipids, proteins and nucleic acids - Phosphate group, 5-carbon sugar, nitrogenous base

What other molecule is made up of phosphates and 5-carbon sugar What other molecule is made up of phosphates and 5-carbon sugar? (hint: it releases energy!) ATP! Adenine Ribose 3 Phosphate groups

Nucleic Acids

Nucleic Acids Nucleic Acids are the chemical link between generations dating back to the beginning of life on earth.  

Nucleic Acids A nucleic acid is a complex macromolecule that stores information in cells in the form of a code.

Nucleic Acids Nucleic acids are made of long chains of nucleotides.   Nucleotides are made of three components: 1. sugar 2. phosphate group 3. nitrogen base

Nucleic Acids Examples of nucleic acids are : 1. DNA 2. RNA

DNA DNA = deoxyribonucleic acid its components are:   its components are: 1. deoxyribose (sugar) 2. phosphate group 3. nitrogen base

The Components and Structure of DNA There are four kinds of bases in in DNA: 1. adenine 2. guanine 3. cytosine 4. thymine DNA is made up of nucleotides. Each nucleotide has three parts: a deoxyribose molecule, a phosphate group, and a nitrogenous base. There are four different bases in DNA: adenine, guanine, cytosine, and thymine.

DNA James Watson and Francis Crick proposed that DNA has a specific pairing between nitrogen bases: Adenine (A) – Thymine (T) Guanine (G) – Cytosine (C) A and G are purines (AGgies eat Purina) C and T are pyrimidines

DNA   Watson and Crick also said the paired nitrogen bases formed two long strands of nucleotides that compliment each other.

DNA Nitrogen Bases are connected between sugars and phosphates They declared, “This structure is a “double helix”.

The Components and Structure of DNA DNA Double Helix The Components and Structure of DNA DNA is a double helix in which two strands are wound around each other. Each strand is made up of a chain of nucleotides. The two strands are held together by hydrogen bonds between adenine and thymine and between guanine and cytosine.

DNA DNA forms chromosomes, units of genetic information which pass from parent to offspring.                         DNA is wound into structures called chromosomes during cell division (prophase)

DNA If you unraveled all your chromosomes from all of your cells and laid out the DNA end to end, the strands would stretch from the Earth to the Moon about 6,000 times.                 

RNA RNA has a different sugar than DNA RNA = ribonucleic acid It’s components are : 1. ribose (sugar) 2. phosphate group 3. nitrogen base

RNA It also has different bases than DNA adenine --- uracil cytosine --- guanine   RNA is also single stranded, not double stranded like DNA.

Review DNA RNA - Double stranded - Single stranded - Sugar = deoxyribose - Sugar = ribose - Adenine pairs with Thymine - Adenine pairs with Uracil

DNA Replication

DNA Replication I. Why Must DNA Replicate? Every time a cell divides, it must first make a copy of it’s chromosomes. Therefore, each cell can have a complete set of chromosomes.

DNA Replication Without replication, species could not survive and individuals could not successfully grow and reproduce.

DNA Replication II. How DNA Replicates DNA is a molecule composed of TWO strands, each consisting of a sequence of nucleotides. The order of the nitrogen bases on one strand mandates the sequence of bases on the complementary strand.

DNA Replication If you know the bases on one strand, you can predict which bases will occur on the complementary strand. A ----- G ----- T ----- C ----- During Replication each strand serves as a template to create a new strand. T C A G This is as easy as break dancing!

Steps in Replication III. Steps In Replication 1) Enzymes break down the hydrogen bonds between the two DNA strands, unzipping the molecule

Steps in Replication 2) As the DNA unzips, free nucleotides (from surroundings in the nucleus) bond to the single strands by base pairing (A-T, G-C)

Steps in Replication 3) Another Enzyme bonds the new nucleotides into a chain ** The result of this process is the formation of TWO DNA molecules, each identical to the original molecule. Replication! Rah,Rah, Rah!

DNA Replication New Strand Original strand Nitrogen Bases Growth During DNA replication, the DNA molecule produces two new complementary strands. Each strand of the double helix of DNA serves as a template for the new strand. Replication Fork Replication Fork DNA Polymerase

DNA Replication

Reflect and Review 1. What are the two types of nucleic acids? 2. What are the three components of a nucleotide? 3. What are the similarities between DNA and RNA? What are the differences? 4. Describe the process of DNA replication. 5. Why does a DNA molecule undergo replication?