What are chromosomes? Where are they located? *Somatic Cells *Nucleus How many are there? Diploid (2n) Different species have a different # of chromosomes

How are chromosomes arranged? *karotype Types of chromosomes *autosomes *sex chromosomes

Common NameGenus and Species Diploid Chromosome Number BuffaloBison bison60 CatFelis catus38 CattleBos taurus, B. indicus60 DogCanis familiaris78 DonkeyE. asinus62 GoatCapra hircus60 HorseEquus caballus64 HumanHomo sapiens46 PigSus scrofa38 SheepOvis aries54

Chromosome classification Centromere position and length of arms can assist in identifying specific pairs of chromosomes, but inevitably several or many pairs of chromosomes appear identical by these criteria.

Q banding: chromosomes are stained with a fluorescent dye such as quinacrine G banding: produced by staining with Giemsa after digesting the chromosomes with trypsin C banding: chromosomes are treated with acid and base, then stained with Giesma stain

E ach of these techniques produces a pattern of dark and light bands along the length of the chromosomes. Importantly, each chromosome displays a unique banding pattern, analagous to a "bar code.”

Parts of a gene *Promotor *Exons *Introns *Protein “codes” *Stop Codes

Every cell within an organism has the same genetic composition (with the exception of its gametes), and yet, obviously skin tissue is very different from nervous tissue. Both neuron and epithelial cell have the genes encoding for neural- and epithelial- specific proteins, but each cell only expresses the genes that it requires, and not other tissue-specific genes.