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DNA & Chromosomes…read more

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DNA in Prokaryotic vs Eukaryotic Cells
· In prokaryotes (bacteria), the DNA molecules are
- Smaller
- Circular
- Not associated with proteins
- Do not have chromosomes
· In eukaryotes, the DNA molecules are
- Larger
- Usually linear
- Found in association with proteins
- Presence of chromosomes…read more

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Chromosome Structure
A chromosome is an organized structure of DNA found in cells.…read more

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DNA to Chromosomes
· The considerable length of DNA (about 2m in every human cell) is
highly coiled and folded.
· The DNA in chromosomes is held in position by proteins.
· This DNA-protein complex is then coiled.
· The coil is looped and further coiled before being packed into
· In this way, DNA is condensed into a single chromosome.
· A chromosome contains just a single molecule of DNA.
· This single DNA molecule has many genes along its whole length.
· Each gene occupies a specific position along the DNA molecule.…read more

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Although the number of chromosomes is always the same for normal
individuals of a species, it varies from one species to another.
· For example, while humans have 46 chromosomes, potato plants have
48 and dogs have 78.
· In almost all species, there is an even number of chromosomes in the
cells of adults. This is because chromosomes occur in pairs called
homologous pairs.…read more

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