Organisation of DNA-Eukaryotes

Organisation of DNA-Eukaryotes

Eukaryotes: Diverse Life Forms

• Eukaryotes encompass a wide range of life forms, including animals, plants, and fungi.
• A defining feature of eukaryotic cells is the presence of a membrane-bound nucleus, which distinguishes them from prokaryotic cells.

Linear Chromosomes within the Nucleus

• In eukaryotic cells, DNA is organised into linear chromosomes.
• These chromosomes are located within the nucleus, which acts as the cell's command centre.
• The linear structure of chromosomes contrasts with the circular chromosomes found in prokaryotic organisms like bacteria.

Tightly Coiled DNA and Histones

• The DNA within eukaryotic chromosomes is tightly coiled and packaged.
• Special proteins called histones play a crucial role in this packaging process.
• DNA wraps around histones, forming a complex called chromatin.
• This coiling allows for efficient storage and regulation of gene expression.

Circular Chromosomes in Mitochondria and Chloroplasts

• Interestingly, circular chromosomes are also present in the organelles mitochondria and chloroplasts.
• These organelles are responsible for energy production (mitochondria) and photosynthesis (chloroplasts) in eukaryotic cells.
• The presence of their own DNA suggests that mitochondria and chloroplasts may have originated from engulfed prokaryotic cells, supporting the endosymbiotic theory.

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Biology

Organisation of DNA-Eukaryotes

Significance of Mitochondria and Chloroplasts

• Mitochondria and chloroplasts use their own DNA to produce some of the proteins needed for their functions.
• This semi-autonomous behaviour supports the idea that these organelles were once independent prokaryotic organisms that formed a symbiotic relationship with eukaryotic cells.