9700 · 5.1
Replication and division of nuclei and cells
This topic explores how living organisms accurately copy their genetic material (DNA) and then divide their cells to grow, repair tissues, or reproduce. You'll learn the precise steps that ensure each new cell receives a complete and identical set of chromosomes, and what happens when this process goes wrong.
Need to know
What you need to know
- **Unwinding:** The enzyme **DNA helicase** binds to the DNA and unwinds the double helix by breaking the hydrogen bonds between complementary base pairs (A-T and G-C). This separates the two strands, creating a replication fork.
- **Template:** Each separated strand acts as a template for the synthesis of a new complementary strand.
- **Synthesis:** Free-floating deoxynucleoside triphosphates in the nucleoplasm align opposite their complementary bases on each template strand.
- **Polymerisation:** The enzyme **DNA polymerase** moves along the template strands, catalysing the formation of phosphodiester bonds between adjacent nucleotides. This joins them into a new strand, forming the sugar-phosphate backbone.
- **Proofreading:** DNA polymerase has a proofreading function, checking for and correcting errors in base pairing to ensure high fidelity of replication.
Explanation
Replication and division of nuclei and cells
- **Unwinding:** The enzyme **DNA helicase** binds to the DNA and unwinds the double helix by breaking the hydrogen bonds between complementary base pairs (A-T and G-C). This separates the two strands, creating a replication fork.
- **Template:** Each separated strand acts as a template for the synthesis of a new complementary strand.
- **Synthesis:** Free-floating deoxynucleoside triphosphates in the nucleoplasm align opposite their complementary bases on each template strand.
- **Polymerisation:** The enzyme **DNA polymerase** moves along the template strands, catalysing the formation of phosphodiester bonds between adjacent nucleotides. This joins them into a new strand, forming the sugar-phosphate backbone.