And Now The Chromosome
We have, so far, discussed the cell and the nucleus, the former containing the latter. Now as we decrease in size, we encounter the chromosome, contained in the nucleus. Another item we need to understand if we wish to understand a little about gene sequencing. We are slowly unravelling the basics of what makes us what we are.
A chromosome is groups of thousands of genes and contains about 60% protein and about 40% DNA and floats around in long strings uncoiled until it is time to reproduce. The number of chromosomes is specific to a species. The human has 46 chromosomes (23 identical pairs). If a human cell has a complete set of 23 pairs of chromosomes it is called 'diploid'. If a human cell has 23 single chromosomes it is called' haploid'.
A haploid cell is one that is involved with sexual reproduction and these are called gametes or sex cells. So it is, that the egg has 23 chromosomes and the sperm has 23 chromosomes, combining to make a 46 chromosome individual. These chromosomes carry all the hereditary information from both parents to make a unique new entity.
All organisms have different numbers of pairs of chromosomes. For example, a camel has 70 pairs, a bat has 44 pairs, an alligator has 32 pairs, lettuce has 18 pairs and a tomato has 24 pairs. We would obviously never confuse a human with a tomato.
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