Final answer:
Human chromosomes are highly conserved with less than one percent difference between homologous chromosomes, except for the sex chromosomes X and Y. Chromosome number doesn't necessarily equate to the amount of DNA. Standardized comparisons in laboratories can use techniques like karyotyping for detailed genetic analysis.
Step-by-step explanation:
Comparison of Human Chromosomes
Different people's chromosomes have an incredibly high degree of similarity, with the difference between any pair of human homologous chromosomes being less than one percent. However, the exception lies in the sex chromosomes, X and Y, which vary greatly, beyond a small region of homology necessary for gamete production. This results in distinctly different genetic makeup between males (XY) and females (XX).
Comparing the chromosomes of different species typically reveals patterns of conservation and divergence in genetic sequences, reflecting their evolutionary relationships. As for the amount of DNA, the number of chromosomes does not necessarily correlate with the amount of DNA a species possesses. To standardize comparisons in a laboratory, quantitative techniques such as fluorescence in situ Hybridization (FISH) for karyotyping can be used, which enable precise measurement and comparison of genetic material.
A human karyotype consists of 22 autosomal chromosomes plus the sex chromosomes, making up the 23 pairs. Karyotypes are vital in identifying chromosomal aberrations and understanding genetic health. The sex chromosomes, particularly the presence or absence of the SRY gene, determine the sex of an individual, with individuals typically having XX chromosomes being female and those with XY chromosomes being male. Females manifest a Barr body, which is an inactivated X chromosome visible in a nucleus, while males do not as they have only one X chromosome.