2. RECALL…
In our first unit (Biochemistry), we learned that there were 4 major organic compounds.
Carbohydrates
Lipids
Proteins
Nucleic Acids
Nucleic Acids serve as the blueprint for proteins
Gives organisms their unique traits like hair/eye color, blood type, height, skin color, etc.
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3. DNA= Code of Life
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4. (de – without, oxy – oxygen, ribo – ribose sugar)
2 Types of Nucleic Acids
1) DNA – deoxyriboNUCLEIC ACID
(de – without, oxy – oxygen, ribo – ribose sugar)
Store and pass genetic information
Sex Cells (sperm & egg) are the ONLY cells that can pass genes/traits down to their offspring.
Code for proteins
2) RNA – riboNUCLEIC ACID
Protein synthesis
Subunits of DNA/RNA: nucleotides
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5. Types of Nucleic Acids
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6. DNA Found in the nucleus of eukaryotes (in cytoplasm of prokaryotes)
DNA nucleotides bond together to form a double helix
Double stranded Helix = twisted ladder
“Rungs” (steps of the ladder) are nitrogen bases
“Sides” are the sugar-phosphate backbone
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7. Nucleotide Structure 3 parts of a NUCLEOTIDE:
Sugar (deoxyribose or ribose)
Phosphate (P with oxygens attached)
4 Nitrogen bases:
Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C) S P
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8. Nucleotide Structure Y like Thymine and Cytosine Adenine
2 classes of nucleotides determined by the base that attaches to the sugar.
Purines
Adenine
Guanine
Pyrimidines
Thymine
Cytosine
Purines are PURE – like AnGels
Pyrimidines –
Y like Thymine and Cytosine
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9. CHARGRAFF’S Base Pairing Rule
Scientists James Watson and Francis Crick showed that DNA shape is a double helix.
A (adenine) hydrogen bonds with T (thymine)
C (cytosine) hydrogen bonds with G (guanine)
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10. Nitrogen Base Pairing
Adenine Thymine
4-eva
Guanine Cytosine
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11. Adenine Thymine Guanine Cytosine
Nitrogen Base Pairing
Adenine Thymine Guanine Cytosine
= Hydrogen Bond
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12. Nitrogen Base Pairing
Adenine Thymine Cytosine Guanine Thymine Adenine Adenine Thymine Guanine Cytosine
Sugar + Phosphate backbone
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13. Compl-e-ment – complement
To complete, finish, or fill something up
NOT this kind…
Compl-i-ment - compliment
“Miss Clark has great earrings on today!”
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14. What is the complementary DNA strand?
EXAMPLE 1
3’ end ’ end
ATTGACCATTGATAGCCGAATA
TAACTGGTAACTATCGGCTTAT
EXAMPLE 2
5’ end ’ end
TCTTCGGAACATTAGTCGAGGC
AGAAGCCTTGTAATCAGCTCCG
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15. In what phase of the cell cycle does DNA copy itself for the new cell?
Q.Q. 11/27/18
In what phase of the cell cycle does DNA copy itself for the new cell?

16. Cell Cycle
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17. S phase of the Cell Cycle
DNA Replication
S phase of the Cell Cycle

18. DNA Replication DNA replication:
Not only does DNA function as the code of life for protein synthesis, DNA also replicates to ensure that every new cell has identical DNA
DNA replication:
Copying of 1 molecule of DNA to make 2 identical molecules of DNA
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19. Steps in DNA Replication
Occurs when chromosomes duplicate (make copies)
An exact copy of the DNA is produced with the aid of enzymes, specifically helicase and DNA polymerase.
Hydrogen bonds between bases break and helicase “unzips” the molecule (opens up the double helix!)
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20. Steps in DNA Replication continued…
Each old strand of nucleotides serves as a template for each new strand
New nucleotides move into complementary positions are joined by the enzyme DNA polymerase.
Practice ANIMATION!

21. DNA Replication
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22. DNA Replication RESULT of DNA replication = 2 identical DNA molecules
REMEMBER: each exposed base can only bond to its complementary base!
Adenine (A) --- Thymine (T)
Guanine (G) --- Cytosine (C)
RESULT of DNA replication =
2 identical DNA molecules
Each DNA molecule is made up of one NEW strand (daughter strand) and one OLD strand (parent strand)
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23. Try this… TAG ACC CAG CCC CCG CAC CTG TTA AAA
Using the base pairing rules of replication, what is the complementary strand of DNA for the following examples:
TAG ACC CAG CCC
CCG CAC CTG TTA AAA
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