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Human Chromosomes
Ones inheritance

During cell division, normally undifferentiated DNA within the nucleus condenses with associated proteins, histones, into well defined observable structures - the chromosomes. In humans there are 23 pairs of chromosomes one of each being donated by each parent. The 'arms' or chromatids and are joined at the centromere. The position of the centromere and length of the chromatids are used in conjunction with banding techniques to identify individual and pairs of chromosomes.

Single chromosome x16,900

In mammals the gender of an individual is determined by the combination of the sex chromosomes. Females posses two X-chromosomes and are said to be homogametic whereas males are heterogametic with one each of an X- and Y-chromosome. Females can only donate an X-chromosome. If the male also donates an X-chromosome the offspring will be female. If the male donates a Y-chromosome the offspring will be heterogametic and consequently male. In mammals the sex chromosomes are very different sizes.

Sex chromosomes x13,400