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 Name Genus and Species Diploid ChromosomeNumber

Buffalo Bison bison 60

Cat Felis catus 38

Cattle Bos taurus, B. indicus 60

Dog Canis familiaris 78

Donkey E. asinus 62

Goat Capra hircus 60

Horse Equus caballus 64

Human Homo sapiens 46

Pig Sus scrofa 38

Sheep Ovis aries 54

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

Each 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.