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# DNA Replication DNA Replication: Identical duplication of DNA in interphase, necessary for cell division. ## Replication Process: 1. **Helicase:** Separates the double helix into two single strands. 2. **Primase:** Creates RNA primers as starting points. 3. **DNA Polymerase:** Adds complementar...

# DNA Replication DNA Replication: Identical duplication of DNA in interphase, necessary for cell division. ## Replication Process: 1. **Helicase:** Separates the double helix into two single strands. 2. **Primase:** Creates RNA primers as starting points. 3. **DNA Polymerase:** Adds complementary nucleotides to and extends the strand in a 5' to 3' direction; ligase joins Okazaki fragments in a 3' to 5' direction. ## Synthesis Mechanisms * **Leading strand:** Continuous synthesis in the 5' to 3' direction. * **Lagging strand:** Discontinuous synthesis in the form of Okazaki fragments, which are joined by ligase. ## Key Concepts * **Semiconservative replication:** Each new double strand contains one original and one newly synthesized strand. * **Accuracy & Rate:** Accuracy and speed differ between prokaryotes and eukaryotes. ## From Gene to Protein * **Transcription:** DNA is converted to mRNA. * **Processing:** Pre-mRNA is processed into mature mRNA. * **Translation:** mRNA is translated by ribosomes into proteins. ## Protein Types * **Structural proteins:** Provide form, e.g., collagen, keratin. * **Motor proteins:** Enable movement, e.g., actin, myosin. * **Transport proteins:** Carry substances, e.g., hemoglobin. * **Defensive proteins:** Protect against diseases, e.g., antibodies. * **Receptor proteins:** Receive signals, e.g., receptors in cell membranes. * **Signal proteins (hormones):** Transmit information, e.g., insulin. * **Storage proteins:** Store substances, e.g., ferritin. * **Enzymatic proteins:** Facilitate chemical reactions, e.g., digestive enzymes. *Note: Some protein names are abbreviated, e.g., z. B. (e.g.)*