What do we know because we have cracked the human genome?

Question

Asked a question about mixed race and skin colour inheritance and someone gave a really good answer but said that after fertilization we don't know where all the genes are going to. Am I stupid or what but I thought that this is what the Human genome project had answered. I thought we knew what all 46 genes did. Am I getting mixed up between chromosomes and genes?

Answer 1

We do know what the genes do. Most of them anyway. However, when two human gametes come together the best we can do is figure out the probability that the offspring will have certain features. Men have tons of sperm cells and women have tons of eggs. We have know way of knowing which two will come together and what dominant or recessive genes those two are carrying. We can only know what is dominant and recessive in the parent and then figure out probability (look up Punnet squares). That's why parents with multiple children have children that all look different. They each get different sets of dominants and recessives each time their parents mate. So even though we know what the genes do we have no way of knowing for sure which dominant and which recessive a child gets from its parents.

Answer 2

There are a couple of questions that you have in here, and a couple of things we should clarify:

First, you are right to say you were mixed up. Humans have 46 chromosomes total. These 46 chromosomes are really two sets of 23 chromosomes, one from each parent.

Spread out over these 23 chromosomes are roughly 25,000 genes. These genes are ecoded, like very long words, in the letters of DNA. The order of ALL of these letters is what the human genome project was about. The human genome is not only the letters in all of the genes, but all of the letters of DNA in between genes. The total length of the human genome is about 3 billion letters!

Back to your question about mixed race: Because you have two copies of all of the 25,000 genes (one copy from each parent), both of your parents contribute to your genetic traits.

And actually, we do know after fertilization where each of these genes (the DNA) will go in your body. They go to every single cell! Whether a gene is 'turned on' in a single cell is a whole different story, though, and maybe what confused you.

To get a little more complicated...

This is where dominant/recessive and mixed traits can be understood. Some versions of a gene work in a way that 'overpowers' (they are dominant) the effect by others. For instance, the dominant version of the gene MC1R is a version that functions to make the skin/hair to make dark color. The recessive version of MC1R does not make any color. So, a dog that has one version of MC1R that makes color and one that does not, will still end up having color (this is why black lab dogs are more common than yellow labs).

Anyway, don't feel stupid. It's all amazingly complicated. And amazingly beautiful how it all works so well.

Have a good day!

Answer 3

One of the biggest advantages to having the complete sequence of an organisms DNA, including human, is that it can be searched through using computers. Often scientists will isolate a part of DNA that is important. If they can get the sequence of that DNA then they can compare their sequence to the sequence of the entire genome. This will tell them where the DNA they have isolated is in the genome. It will also tell them if there are any mutations in that DNA.
Another advantage to sequencing the genome is that we can compare the DNA of different species. For instance if scientists discover an interesting gene in fruit flies that has a very similar sequence to a gene found in humans than that tells them that gene has probably retained its function over time. This helps scientists working with lower animals make connections between what they are working on to humans.
What sequencing the genome does not tell us is what the functions of the genes are or even where most of the genes are located. To discover those things still requires a lot of work.
Sequencing the genome was only the first, necessary step, to understanding what all the genes are and how they work.

Answer 4

Interestingly enough, though we are roughly aware what most of the genes do, we are finding out that we have barely put a dent in the human genome. A small percentage of our DNA is used for instructions (genes/info to make proteins) the rest up until recently has been considered to be filler DNA, or basically "junk". As of recently, we are realizing that the junk DNA probably does something. Check out this short article:

http://www.boston.com/news/science/articles/2007/06/14/dna_study_challenges_basic_ideas_in_genetics/?page=2

Don't fret...it is unbelievably complicated...and we scientists still don't know most of the answers.

Answer 5

We know where to start, and thus, we are starting to delve into the applications of the genes. Mind you, we only cracked one person's genome. So, we know about them, but now we need to compare and find the differences.

Answer 6

Until we know how they interact and the integrals of the individual building blocks of each, we are a long way off from a full understanding.

Answer 7

GOOD QUESTION...We can grow an ear, on the back of a mouse.

Answer 8

WE EVAN HAVE WRANGLER GENES