The ends of chromosomes contain regions referred to as telomeres.

染色體的末端包含稱為端粒的區域。

These telomeric regions consist of telomeric repeat sequences.

這些端粒區由端粒重複序列組成。

The exact sequence of telomeric repeat can vary from species to species.

端粒重複的確切序列因物種而異。

The repeat sequence shown here is found on telomeres of human chromosomes. Since DNA replication can only proceed in the 5' to 3' direction and requires a primer, it is not possible for a DNA polymerase to replicate the 3' ends of linear chromosomes.

這裡顯示的重複序列存在於人類染色體的端粒上。 由於 DNA 複製只能沿著 5' 到 3' 的方向進行，並且需要引物，是以 DNA 聚合酶不可能複製線性染色體的 3' 端。

If this problem were not corrected, chromosomes would shorten with each cycle of DNA replication.

如果這個問題得不到糾正，染色體就會隨著 DNA 的每個複製週期而縮短。

The addition of telomeric repeat sequences by an enzyme complex referred to as telomerase assures that this shortening does not occur. Telomerase is a unique and interesting enzyme because, in addition to having DNA polymerase activity, it also contains an RNA sequence that provides a template for the synthesis of telomeric repeat DNA.

被稱為端粒酶的酶複合物會添加端粒重複序列，以確保這種縮短不會發生。 端粒酶是一種獨特而有趣的酶，因為它除了具有 DNA 聚合酶活性外，還含有一種 RNA 序列，可為端粒重複 DNA 的合成提供模板。

Part of the RNA sequence hybridizes with the single-stranded overhang on the DNA strand, leaving a single-stranded overhanging RNA sequence.

部分 RNA 序列與 DNA 鏈上的單鏈懸垂雜交，留下單鏈懸垂 RNA 序列。

The repeat unit shown here is from Tetrahymena, which is the model organism used in telomere and telomerase research. The DNA polymerase function of telomerase then synthesizes a DNA strand complementary to the RNA found in the telomerase and subsequently translocates to the end of the newly synthesized strand, and the process repeats itself.

這裡顯示的重複單元來自四膜蟲，四膜蟲是端粒和端粒酶研究中使用的模式生物。 端粒酶的DNA聚合酶功能會合成一條與端粒酶中的RNA互補的DNA鏈，然後轉位到新合成鏈的末端，這個過程會不斷重複。

Many cycles of repeats can occur.

可能會出現多次重複循環。

Once telomerase has completed its function, DNA primase synthesizes an RNA primer near the 3' end, and DNA polymerase fills in the vacant region.

端粒酶完成其功能後，DNA引物酶會在3'端附近合成一個RNA引物，然後DNA聚合酶會填補空缺區域。

A short region at the 3' end will remain single-stranded. The end result is that telomerase will have added many repeat sequences from a few dozen to a few hundred.

3'端的一個短區域將保持單鏈。 最終的結果是，端粒酶會增加許多重複序列，從幾十個到幾百個不等。

This prevents chromosome shortening.

這可以防止染色體縮短。