DNA Replication
| English | Chinese | Pinyin |
|---|---|---|
| replication | 复制 | fù zhì |
| template | 模板 | mú bǎn |
| DNA polymerase | DNA聚合酶 | DNA jù hé méi |
| semi-conservative | 半保留 | bàn bǎo liú |
Copying the code
- Before a cell divides, it must copy all of its DNA.
- Both new cells need a complete, identical set of instructions.
- The double-helix structure makes this copying possible.
- The process is called DNA replication.
Unzipping the helix
- Replication begins by breaking the base pairs.
- The two strands separate, like a zip opening.
- This exposes the bases along each strand.
- Now each strand can guide the building of a new partner.
Why must a cell copy its DNA before dividing?
Replication ensures both daughter cells receive a complete, identical copy of the DNA.
Each strand is a template
- Each old strand acts as a template 模板.
- Its base sequence decides the new strand by base pairing.
- The enzyme DNA polymerase DNA聚合酶 adds matching bases along it.
- A pairs with T and G with C, so the copy is exact.
How DNA is copied
Step through replication — the helix unzips and each old strand is used as a template for a new one.
During replication, each old strand acts as a…
Each old strand is a template: its base sequence decides the new strand by base pairing.
The enzyme DNA polymerase builds the new strand by adding matching bases.
DNA polymerase reads the template and adds the complementary base at each position.
Semi-conservative copying
- Replication 复制 makes two DNA molecules from one.
- Each new molecule has one old strand and one brand-new strand.
- Because each keeps half of the original, it is semi-conservative 半保留.
- The two copies are identical to the starting DNA.
Because each new DNA keeps one old strand, replication is called ____-conservative.
Replication is semi-conservative: each copy has one original strand and one new strand.
Select all true statements about DNA replication.
Replication keeps the old strands (semi-conservative); it does not discard them. The other three are correct.
Replication is semi-conservative: it does not build two entirely new molecules and throw the old one away. Each daughter DNA keeps one original strand and pairs it with a new one. Half old, half new — that is the key idea.
Right before a cell divides:
- The cell copies all of its DNA during interphase.
- Each chromosome becomes two identical copies, joined together.
- When the cell divides, each daughter gets one full copy — thanks to replication.
DNA replication copies the genetic code before cell division. The helix unzips, and each old strand serves as a template while DNA polymerase adds matching bases. The result is semi-conservative: each new DNA has one old strand and one new strand, giving two identical copies.