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 7 of about 7.
113 days ago.
Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or
part of a third copy of chromosome 21. This syndrome can be detected during pregnancy or after the birth of the child. However, the American Congress of Obstetricians and Gynecologists (ACOG) recommend that every woman should undergo a Down’s syndrome screening test.
Down's syndrome test- http://nace.igenomix.co.in/ firstname.lastname@example.org
152 days ago.
When I found Dr.Agumba I was in desperate need of bringing my ex lover back. He left me for another woman and I was left in the dark. It happened so fast and I had no say in the situation at all. He just dumped me after 3 years with no explanation. I contact Dr.Agumba through his website and he cast a love spell to help us get back together. Shortly after he did his spell, my boyfriend started testing me again and felt horrible for what he just put me through. He said that I was the most important person in his life and he knows that now. I highly recommends Dr.Agumba anyone in need of help.Email:email:email@example.com or call him on +2348143391398 i am resa from Australia.
170 days ago.
Hello my sisters my names are Tracy Pink, am from Canada i want to share my happiness with everybody and letting them know the secret of my happiness, the secret of my happiness is Dr okpa the great herbalist, who help to stop my miscarriage and made me a mother after been losing 3 children through miscarriage, but Dr okpa put an end to this situation, now am a mother and am living happily with my husband and my new baby which i love so much, am using this medium to thank Dr okpa for the great work he did for me with his herbs, Thanks be unto him for helping me, my sisters out there i wan yout to thank Dr okpa for the great work he did for me and my husband or if you need his help also you can contact him through his cell number: +2348056563186 or email him via; firstname.lastname@example.org
Once again thank Dr okpa
Got a bun in the oven
1567 days ago.
Anyone have a balanced translocation? Cindie
2121 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
2340 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
2344 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.