BRAINCAKEChromosomes
In Eukaryotes, DNA is associated with and bound to proteins called histones.
The DNA double helix is wound round the histones to fix it in position and then coiled. The DNA-histone complex is then looped and further coiled into a chromosome.
The number of chromosomes varies from species to species but is always the same for each member of a species.
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Key terms in this lesson
- chromatin
- DNA loosely wound around histone proteins, found in the nucleus when the cell is not dividing.
- eukaryotic cell
- A cell that has a nucleus and membrane-bound organelles.
- centromere
- The region of a chromosome where the two sister chromatids are held together and where spindle fibres attach.
- chromatid
- One of two identical copies of a chromosome, joined at the centromere, formed by DNA replication.
- species
- A group of organisms with similar characteristics that can interbreed to produce fertile offspring.
More in DNA, Genes and Protein Synthesis
- Genes
- The Genetic Code
- Features of the Genetic Code
- Homologous Chromosomes
- Alleles
- The Human Karyotype
- Protein Synthesis
- RNA
All 15 lessons in DNA, Genes and Protein Synthesis · All AQA AS-level Biology topics