Final answer:
Eukaryotic chromosomes are made of DNA and proteins, with nucleosomes as a key feature where DNA wraps around histones. They have varying levels of condensation including euchromatin and heterochromatin, with centromeres and telomeres playing critical roles in chromosome segregation and protection.
Step-by-step explanation:
Eukaryotic Chromosomes Features
A chromosome is a structure within the nucleus that is made up of DNA, the hereditary material. Eukaryotic chromosomes have distinctive features, specifically:
- Nucleosomes: These are structures where DNA is wrapped around a set of histone proteins, forming a complex that appears like beads on a string. Each nucleosome consists of DNA wrapped around an octamer of histones, including two copies each of four different histones, plus a fifth histone (H1) that binds to the linker DNA between nucleosomes.
- Levels of Chromosome Condensation: Chromatin, which is a combination of DNA and proteins, can exist in a less condensed form called euchromatin or a more condensed form called heterochromatin. The latter is tightly packaged and includes the centromere and telomere regions, where genes are not typically expressed.
- Centromere and Telomere Regions: These are specific parts of the chromosome crucial for proper segregation during cell division. The centromere is the region where sister chromatids are held together, while telomeres protect the ends of chromosomes from deterioration.
Each of these components plays a vital role in the organization, protection, and replication of eukaryotic DNA. When a cell is preparing to divide, the chromatin condenses into highly compacted chromosomes, approximately 700 nm in width, ensuring the safe transmission of genetic information.