ChromosomesHow many chromosomes does a normal human being have?
Chromosomes, DNA and genes
Chromosomes are thread-like structures found in the nucleus of all cells (except red blood cells), which contain our genetic meterial (DNA). Chromosomes come in pairs, and a normal human cell contains 46 chromosomes, 22 pairs of autosomes and one pair of sex chromosomes.
Courtesy: National Human Genome Research Institute. Click the link for a very good glossary
on everything gene related.
DNA, or deoxyribonucleic acid, is the chemical inside the nucleus of a cell that carries the genetic instructions for making living organisms.
A DNA nucleotide is made of a molecule of sugar, a molecule of phosphoric acid, and a molecule called a base. The bases are the 'letters' that spell out the genetic code. In DNA, the code letters are A, T, G, and C, which stand for the chemicals adenine, thymine, guanine, and cytosine, respectively. In base pairing, adenine always pairs with thymine, and guanine always pairs with cytosine.
Genes are pieces of DNA. Most genes contain the information for making a specific protein.
Sex chromosomes. Boy or Girl?
When a spermcel and an egg melt, one chromosome of each pair will be given to the new human being. Chromosome pair 23 will do the same. Females have XX, males have XY (Like in the picture at the right). If the man donates the X part of this pair it will be a girl, otherwise it will be a boy.
Our genetic information, sometimes described as the 'Book of Life', can be envisaged as a compendium comprising two volumes. It is important to remember however that our environment also plays a major role in how we develop and how our bodies work.
Read more at genetics.com.au |
Most people have 46 chromosomes, in 23 pairs, but some have an extra copy
of one chromosome, called a trisomy because there are three of one
chromosome pair. This extra chromosome can lead to a variety of
abnormalities. The most common trisomy is called Down syndrome, a trisomy of chromosome pair 21.
Read more about trisomyComments: Chromosomes
Comments 1 to 4 of about 4.
Got a bun in the oven
1350 days ago.
Anyone have a balanced translocation? Cindie
1905 days ago.
Be aware that even though there ARE false positives AMnio's are 99.9% accurate. CVS tests are a bit less accurate since the cells they get are from the placenta and it is possible for the placenta to have abnormal cells in it but the baby to be ok. My firstborn son TJ has down syndrome and carried my K10 mutation which results in a skin disorder known as EHK. kristy2
2123 days ago.
i just came back from the docs thay called me in coz of the ultrasound i had 2 days ago he told me thay found some abnormalies with my mans kidneys thay call it a genetic cromozone disorda were sumthing went wrong with the cromozones and sum organs didnt =form propurly there is a lining on the inside of the kidney that seperat the canel to the blada an sum where down the line it hasnt formed properly my poor little man i want to cry so bad but i am trying to be strong till my hubby gets home from work misslynnz
2127 days ago.
My baby is healthy! He is 9 months old. Because I was 37 the Doctors suggested I do the CVS test. It came back abnormal with Tetrapolidy. They told me my baby would not live because he had 92 chromosomes. They suggested I do the amino, it came back abnormal. Well, I had faith. . . and I have a healthy baby boy. Good thing I did not listen to the 'false positive' results. If you get bad news. . . remember it could be a 'false postive' like in my pregnancy. My prayers are with you.