1. DNA and Replication (Deoxyribonucleic Acid)

2. Chromosomes and DNA Our genes are on our chromosomes.
Chromosomes are in the nucleus and made up of a chemical called DNA.
{Ask students where the chromosomes are in this picture. Or ask them where the DNA is. Remind them that the mitochondria also have DNA.}

3. What is DNA’s Function? Hereditary Instructions
Chemical code for every trait
“Blueprint” for making Proteins
Located in the Nucleus

4. Why do we study DNA? We study DNA for many reasons, e.g.,
Medical benefits such as cures for diseases.
(Gene Therapy)
Better food crops.
( GMO’s -Genetically Modified Organisms).
Crime Scene Identification
About better food crops, this area is controversial. There is a Dr. Charles Arntzen who is working on bioengineering foods with vaccines in them. People in poor countries could be immunized against diseases just by eating a banana, for instance.

5. Genetic material of cells…
GENES – units of genetic material that CODES FOR A SPECIFIC TRAIT
Called NUCLEIC ACIDS (DNA & RNA)
DNA is made up of repeating molecules called NUCLEOTIDES
Nucleic acids: Many nucleotides linked in a long chain

6. DNA Nucleotide
Basic structure of DNA is a sugar-phosphate backbone with 4 variable nitrogenous bases. This structure is called a nucleotide. P
Phosphate
Group
Nitrogenous base
(A, G, C, or T) O C1 C4 C3 C2 5
Sugar
(deoxyribose) N S

7. Four nitrogenous bases
DNA has four different bases
which are connected by hydrogen bonds
Cytosine C
Thymine T
Adenine A
Guanine G
BALANCED
These four bases are abbreviated by using their respective first letters.

8. Chargaff’s Rule Adenine must pair with Thymine
Guanine must pair with Cytosine
Their amounts in a given DNA molecule will be about the same. T A G C

9. The Shape of the Molecule
DNA is a very long polymer.
The basic shape is like a twisted ladder
This is called a “double helix”.
With complementary base pairs (A-T, C-G)
{Show students a model of the double helix. Explain what a spiral is and a helix is.}

10. DNA Molecule

11. Rosalind Franklin – Studied the structure of DNA USING X-Ray
Rosalind Franklin – Studied the structure of DNA USING X-Ray. She discovered that DNA is a helical structure.
X-ray photo of DNA.
Double Helix

12. Watson & Crick’s Model
Watson and Crick – build the DNA molecule model from Franklin’s X-ray.
Nobel Prize 1962

13. What is the correct complimentary DNA strand for the following CGTAAGC?
GCATACG
GCATTCG
CCATTGC
CGATACG

14. Which of the following codes for your traits?
Sugars
Nitrogen Bases
Phosphates
All of the above

15. What is the building block of a nucleic acid?
Polymer
Lipid
Carbohydrate
Nucleotide

17. Vocabulary Replication – the process of DNA duplication.
Replication fork – Site where DNA strands separate and replication occurs.
Enzyme – a protein that facilitates a specific chemical reaction in the body.
Helicase: Unzips
DNA strands
DNA Polymerase: Joins
nucleotides back together Also, has proofreading function. Detects incorrectly paired nucleotides and corrects them.

18. Vocabulary
Leading strand (5’ to 3’) – DNA strand that forms as a continuous strand during DNA replication.
Lagging strand (3’ to 5’) – DNA strand that forms as a series of short segments, called Okazaki fragments, which are then connected together.

19. What is DNA replication?
Happens in the nucleus
Happens during Interphase (S phase)
During DNA replication, the DNA molecule produces two new complementary strands.
Each strand of DNA serves as a template for the new strand.
Described as semiconservative because each DNA molecule has one new strand and one original strand.

20. Steps of DNA Replication
DNA Replication--- transcription--- translation
The two original strands of DNA are separated by helicase at the replication fork
DNA Polymerase adds complimentary nucleotides to each strand
Two DNA molecules from that are complementary, but identical to the original

21. Replication conserves genetic information
Each parent or original strand of DNA serves as a template this means the genetic information stays the same or is conserved.

22. DNA Replication

23. What did we learned?
DNA, the genetic material of organisms, is composed of four kinds of nucleotides.
Each nucleotide consists of a sugar, a phosphate group and one of four bases.
Sugars and phosphates on the outside
Nitrogenous bases paired by hydrogen bonds (A with T, C with G)
The paired strands form a twisted-zipper shape called a double helix.
Before cell division, DNA copies itself in a process called replication.
During replication, DNA separates into two strands, and produces two new complementary strands following the rules of base pairing.

24. What is the essential question?
How does replication ensure that identical copies of DNA are made?

25. Genetic Diversity…
Different arrangements of NUCLEOTIDES in a nucleic acid (DNA) provides the key to DIVERSITY among living organisms.

26. The figure to the right shows which of the following?
a. Translation
b. Replication
c. Transcription
d. Protein Synthesis

27. Which choice describes DNA after replication has taken place?
A. one molecule with two original strands and one molecule with two new strands
B. two molecules, each with one original and one new strand
C. two molecules, each with two new strands
D. two molecules, each with two old strands

28. At what point in the cell cycle does DNA replication occur and why?
A. before a cell divides, to provide each of the two resulting cells with a complete set of DNA instructions
B. before a cell divides, to ensure that the DNA will fit into the resulting cells
C. during cell division, to ensure that the DNA will fit into the resulting cells
D. after a cell divides, to provide each of the two resulting cells with a complete set of DNA instructions.

29. Differences in DNA and RNA

31. DNA Replication--- transcription--- translation
DNA is replicated in the nucleus.
DNA is transcribed into RNA in the nucleus
RNA is translated to protein in the cytoplasm

32. RNA types
Messenger RNA (mRNA): copied from DNA, carries information from chromosomes to ribosomes.
2. Ribosomal RNA (rRNA): make up ribosomes
3. Transfer RNA (tRNA): transport amino acids to ribosomes

33.  Look at the figure below: What structure does this figure show?
A. DNA B. RNA
C. Protein
D Amino Acid

34. A. Cytoplasm
B. Nucleus
C. Ribosome
D. Cell Membrane