(a)	+Chromosomes+(Q+1-3)

=**What is a chromosome?**= media type="custom" key="18967342"

- Entire piece of DNA - Has DNA tightly coiled around histones (proteins) - Carries genes and hereditary information - Several threadlike strands of DNA in the nucleus



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It is made out of long chain of nucleotides, and these necleotides are twisted together like a ladder in a pair (shown on the picture above)
 * DNA structure:**



Structure of a chromosome =Number of chromosomes and different species= The number of chromosomes varies depending on the type of species. Table provided from //__Chromosome Numbers in Different Species__//

What is a karyotype? Show one and explain how we use it for humans.
Dictionary definition: A simple photograph of chromosomes arranged. It shows the number and visual appearance of the chromosomes in the cell nuclei of an organism or species. Through this, they can identify the visual of the choromosomes and if the person has extra choromosome. (Source: Google Definition, [] )

media type="youtube" key="RTo2lRgfluI" height="315" width="560" A video to help with the understanding of Karyotype's.

Scientist will look at the karyotype from different cell of same person and analyze the choromosome in it.
 * "In this case 100 cells were examined and 65 had an additional 18th chromosome making 47 chromosomes in each cell. 35 contained the usual compliment of 46. The actual karyotype, or photograph, would be of two different cells, one with the additional 18th chromosome and one without." (Source of pitcture and text: **[])

=What can a Karyotype tell us?= 1. The number of chromosomes a person has 2. The gender of each individual. -> This is because it includes individual information about each chromosome. -> The last two chromosomes determine the gender of a person. See below:


 * == Female == || == Male == ||
 * == XX == || == XY == ||

Works Cited //Chromosome Numbers in Different Species//. N.p., n.d. Web. 30 Jan. 1998. .

“What is a chromosome?” //Genetics Home Reference//. N.p., n.d. Web. 21 May 2012. .