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 it’s components are:   it’s components are: 1. deoxyribose (sugar) 2. phosphate group 3. nitrogen base

DNA James Watson and Francis Crick proposed that DNA has a specific pairing between nitrogen bases: 1. adenine (A) 2. thymine (T) 3. cytosine (C) 4. guanine (G)

Nitrogen Bases

DNA adenine ---thymine guanine --- cytosine   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”

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 -Double stranded -Sugar = deoxyribose -Adenine - Thymine RNA - Single stranded - Sugar = ribose -Adenine - 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. (during interphase) 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. 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

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. Write Your Own (write your own question and answer it)