1. Structure and Function of DNA

2. Structure of DNA(deoxyribonucleic acid)
Discovered by Watson & Crick in 1953
DNA is a nucleic acid
DNA is made up of small subunits called nucleotides

3. The nucleotides are made up of:
deoxyribose(sugar)
phosphate group
nitrogen bases-4 types Adenine- A Guanine-G Cytosine- C Thymine-T

4. DNA is actually 2 long chains of nucleotides that are joined together in the form of a ladder. The ladder is twisted in the form of a double helix or spiral

5. Structure of DNA Nucleotide Hydrogen bonds Sugar-phosphate backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)

6. The sides of the ladder are composed if alternating deoxyribose(sugar) and phosphate. The rungs of the ladder are composed of pairs of nitrogen bases.

7. The nitrogen bases always pair up in a specific pattern.
Adenine(A) pairs up with Thymine(T)
Guanine(G) pairs up with Cytosine(C)
Example
A G C T A C G C A one side
T C G
A T G
C G T
other side

8. All organisms have the same type of nucleotides
All organisms have the same type of nucleotides. The nucleotide arrangement provides for all the different types
Ex- A mouse and a rosebush have the same nucleotides. However, they are different because their nucleotides are in different orders.
*This sequence of nucleotides forms the genetic information(code) of an organism.

9. Replication of DNA
Before meiosis and mitosis (during Interphase) a copy of DNA must be made so that when the new cells are formed, they each get an exact copy of the genetic information.
This DNA copy is made through a process known as replication.

10. Steps of Replication
During replication, each strand serves as a pattern or TEMPLATE to make new DNA molecule.
First step: DNA (H bonds are broken) unzips into 2 strands
Second step: free nucleotides join onto “unzipped” strands to form 2 new strands of DNA
2 complete strands will result, these will be exactly alike

11. Figure 12–11 DNA Replication
Section 12-2
Original strand
DNA polymerase
New strand
Growth
DNA polymerase
Growth
Replication fork
Replication fork
Nitrogenous bases
New strand
Original strand
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12. GCC CGG AAA UUU CGC GCG TTT ATT UAA AUU
Warmup- Transcribe the DNA and translate the codon sequence into a protein.
DNA
mRNA
tRNA
Amino acid
GCC
CGG
AAA
UUU
CGC
GCG
TTT
ATT
UAA
AUU