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This chapter provides an overview of chromosomes, including their structure and organization in the nucleus. It discusses the different types of chromosomes, such as sex chromosomes and autosomes, and explains the concepts of haploid and diploid cells. The chapter also introduces the karyotype technique and its role in identifying genetic disorders related to chromosome abnormalities.
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CHAPTER 8Chromosomes pp. 151-153
Chromosomes: coiled and compact DNA in nucleus • DNA wrapped tightly around proteins called histones • Chromatids: two halves of a dividing chromosome • Chromatids joined by a centromere
Chromosome number: each organism has a specific number of chromosomes • Sexchromosomes: determine sex of the organism (X or Y) female: XX male: XY • Autosomes: all other chromosomes • All organisms have two copies that are homologous
Haploid vs Diploid • Haploid (n): only 1 set of chromosomes (n=23) like egg or sperm cells • Diploid (2n): having 2 sets of chromosomes (2n=46) • morphologically similar: homologous • one set from mom and one set from dad • 2 haploid cells (sperm and egg) can combine to make a diploid (zygote)
Karyotype: photo of chromosomes • Block cells in cell division and stain the condensed chromosomes with dye • Thinnest bands contain over a million base pairs and hundreds of genes • Bands can be used to identify chromosomes and possible genetic disorders due to the wrong number of chromosomes