So what do you know about Chromosomes?
A chromosome is a single piece of DNA that contains many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.
A Chromosome is an organized structure of DNA and protein and are found in nearly every cell of your body in the nucleus of each cell. The cells in your body have 23 pairs of chromosomes in each cell which makes a total of 46 chromosomes each. Your red blood cells do not have a nucleus and therefore do not have chromosomes in them. The male sperm cells and female egg cells contain only 23 chromosomes each because when they join they normally give one chromosome each to the developing embryo. The chromosomes contain our DNA which makes us who we are.
A deletion in a chromosome means that a part or segment of the chromosome is missing (please see the black and white segments in the pictures of pairs of chromosomes below.) It can also be called a partial monosomy (monosomy means that the person has one less chromosome). If you see "del" in a karyotype name it means deletion.
This picture shows a cell with the nucleus and the chromsomes contained in it. In the box at the right shows that the middle of the chromosome is referred to as the centromere and the ends of the chromosome are referred to as the telomere. The shorter portion of the chromosome above the centromere is called the "p" arm and the longer portion below the centromere is called the "q" arm of the chromosome. You will usually see "p" or "q" in the karyotype name.
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Karyotype and g-Banding
Click on the Picture below to view the 23 sets of chromosomes in greater detail. Notice chromosome 3's black and white
bands or segments.
bands or segments.
Is there a standard way to diagram A chromosome?
Geneticists use diagrams called ideograms as a standard representation for chromosomes.
Ideograms show a chromosome's relative size and its banding pattern. A banding pattern is the characteristic pattern of
dark and light bands that appears when a chromosome is stained with a chemical solution and then viewed under a microscope.
These bands are used to describe the location of genes on each chromosome.
Idiogram of G-banded chromosome - Male is same except without the Y.
Click on the image below for a more detailed view of each chromosome banding.
Ideograms show a chromosome's relative size and its banding pattern. A banding pattern is the characteristic pattern of
dark and light bands that appears when a chromosome is stained with a chemical solution and then viewed under a microscope.
These bands are used to describe the location of genes on each chromosome.
Idiogram of G-banded chromosome - Male is same except without the Y.
Click on the image below for a more detailed view of each chromosome banding.