DNA notes

DNA
What is DNA? 

DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).

The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.

An important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the old cell.

Gene: 
-> Are made up of DNA
-> contain the instructions on building the proteins that enable our bodies to function


Chromosomes
XXY Syndrome => Kleinfelters Syndrome. This disorder affects only boys. 
Symptoms: development of breasts, spare facial hair, and an inability to produce sperm.

XYY Syndrome affects only boys. There are no noticeable physical differences with this disorder. 
Symptoms: increased activity, delayed mental maturity, and in creased tendency for learning problems in school.

XXX Syndrome =>Triple or Triplo X. This disorder affects only females. Again, there are no physical indications of Triplo X. 
Symptoms=> possible delayed menopause, and increased probability of delayed development in motor function, speech, and maturation

XO Syndrome =>Turner Syndrome and affects only girls. There are minimal physical abnormalities and Turner’s does not affect intellect. The primary effect of Turner’s is due to the missing X chromosome. This causes infertility.

Chromosomes: 44+x

Female: XX chromosomes, 

• can be divided into two ‘X’ chromosomes 
• double ‘X’ and ‘O’

Male: XY chromosomes

• can be divided into ‘X’ and’Y’ chromosomes
• double ‘Y’ and double ‘x’

Chromosomes => genes wrapped around a protein

- Egg has 23 pairs of chromosomes, sperm 23 pairs chromosomes
- Female has only X chromosomes, however a male has both X and Y chromosomes
- All homosapiens need at least 1 X chromosome. A Y chromosome by itself will be aborted.