The nucleus is the largest organelle in an animal cell. It contains numerous strands of DNA, the length of each strand being many times the diameter of the cell. Unlike the circular prokaryotic DNA, long sections of eukaryotic DNA pack into the nucleus by wrapping around proteins. As a cell begins to divide, each DNA strand folds over onto itself several times, forming a rod-shaped chromosome.
- strand [strænd] n.串，(绳子的)股
- diameter [daiˈæmitə] n.直径
- pack into [pæk - ˈintu] v.将……装(塞，挤)入
- wrap [ræp] v.缠绕
- chromosome [ˈkrəuməsəum] n.染色体
