![**Section 8.3: DNA Replication Power Notes**
**General Description:**
This diagram illustrates the process of DNA replication, depicting the stages and structures involved.
**Left Column: Process:**
1. **[Box 1]**: Illustrates the beginning of DNA replication where the double helix structure begins to unwind.
2. **[Box 2]**: Shows further unwinding and the beginning of strand separation.
3. **[Box 3]**: Indicates the complementary base pairing and synthesis of new DNA strands.
4. **[Box 4]**: Represents the completion of replication with two identical DNA molecules.
**Right Column: Identify the Structures:**
1. **[Label 1]**: Identifies the original DNA strand.
2. **[Label 2]**: Points to the replication fork where the strands separate.
3. **[Label 3]**: Highlights the new, complementary nucleotides pairing with the original template strand.
4. **[Label 4]**: Marks the newly synthesized DNA strand.
**Diagram Explanation:**
The central diagram is a detailed illustration of a DNA double helix unwinding. Arrows indicate the direction of strand separation and the movement of new nucleotide bases towards the separated strands, demonstrating the replication process. The end result shows two new DNA molecules, each consisting of one original and one newly synthesized strand, symbolizing the semi-conservative nature of DNA replication.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F4544c423-9ef5-4f1a-aedf-f0473ee49d75%2F5f745d7c-b685-4445-a38f-0d8bec0e5758%2Fu7grbrq_processed.png&w=3840&q=75)
J.D Watson and F.H.C.Crick(1935) proposed a double helix model of DNA molecule, this is the widely accepted model.According to this Watson and Crick model both the strands of DNA were connected by hydrogen bonds and are twisted helically.
These strands contain purine which pairs with pyrimidine on the opposite strands. A strand of DNA is a polymer chain which is having four nucleotides ie A, T, G, C. These double strands joined together to form a double-helical structure. A combine with T with the help of two hydrogen bonds and G pairs with C with the help of three hydrogen bonds.
In this,
A=Adenine
T=Thymine
G=Guanine
C=Cytosine.
In RNA only Thymine is replaced by Uracil means A now pairs U with the help of two hydrogen bonds.
These double strands run anti-parallel to each other.
Watson and Crick postulates:-
1.The two strands with hydrogen bonds are about 20A0. The double helix coils in the right-hand direction(clockwise direction) and it completes a turn of 34A0 and it includes 10 nucleotides.
2.The helical turning results in a double helix which forms a major and minor groove.
3.The major groove is the site for the attachment of protein.
4.The backbone of the double-helical structure is made up of a Sugar-phosphate backbone(Nucleoside).
5.It also suggests it copying mechanism of genetic information.
6.The DNA consists of Nucleotides which is made up of -Nucleosides, sugar, and phosphate.
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