Year 10 Science · Unit 1 · Lesson 3
Foundation Worksheet
Learning Goals
Order the steps
Number the events from 1 to 7 to show the correct order of DNA replication. Event 1 = what happens first.
| Order | Event |
|---|---|
| DNA polymerase adds complementary nucleotides to each template strand | |
| The cell uses its new DNA copies during cell division | |
| Helicase enzyme unwinds and separates the two DNA strands at the replication fork | |
| Two identical DNA molecules are produced, each with one original and one new strand | |
| Proofreading enzymes check the new strand for copying errors | |
| The double helix begins to unzip at a specific starting point on the chromosome | |
| Ligase enzyme seals any remaining gaps in the new strand, completing the new molecule |
True or False? Fix the false ones
Circle T or F for each statement. If the statement is false, rewrite it correctly on the line below.
DNA replication is described as semi-conservative because each new DNA molecule contains one original strand and one newly made strand.
Correct it:
Helicase adds new nucleotides to the growing DNA strand during replication.
Correct it:
Meiosis produces 4 daughter cells, each containing half the original number of chromosomes (23 in humans).
Correct it:
DNA replication occurs after cell division is complete, so the new cells can rebuild their DNA.
Correct it:
1. Explain why DNA must be replicated before a cell divides. What would happen if a cell divided without first copying its DNA?
2. State two purposes of mitosis in the human body.
Wrap Up
In one sentence, what was the main idea of this lesson?