1. Nucleic Acids

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

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

4. 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

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

6. DNA DNA = deoxyribonucleic acid it’s components are:
it’s components are:
1. deoxyribose (sugar)
2. phosphate group
3. nitrogen base

7. 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)

8. Nitrogen Bases

9. DNA adenine ---thymine guanine --- cytosine
Watson and Crick also said the paired nitrogen bases formed two long strands of nucleotides that compliment each other.

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

11. 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)

12. 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.
                

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

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

15. Review DNA -Double stranded -Sugar = deoxyribose -Adenine - Thymine
RNA
- Single stranded
- Sugar = ribose
-Adenine - Uracil

16. DNA Replication

17. 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.

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

19. 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.

20. 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!

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

22. 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)

23. 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!

24. DNA Replication

26. 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)