Question

what is a gene?

Answer 1

this is actually a very hard question to answer. Even though it is simple, it really isn't :P

Answer 2

lets explain it like this A sequence of DNA that codes for a mRNA which is then translated into a functional protein

Answer 3

Now you might ask: "So, this “gene” has all of the information required to make a protein?
"

Answer 4

No, of course not. That requires, ribosomes, shuttling proteins and the like. But the gene does contain the code for that says how to build the protein.

Answer 5

now you might ask, "The rest of the DNA – the non-coding DNA – must have nothing to do with genes, right?"

Answer 6

Well, no…it looks like most of this DNA – most of the genome – is involved in transcription regulation through many different mechanisms: histone affinity, microRNAs, siRNAs, even ‘simple’ steric hinderance

Answer 7

holy crap l0l

Answer 8

haha,
but now
"...so the “gene” knows how much protein to make?"

Answer 9

Well, no...that requires trans- as well as cis- regulatory elements – enhancers, promoters, repressors

Answer 10

and: "…and contains all of the information necessary to code for an organism, such that knowing the DNA code for a cat, for example, would allow me to make a cat in the lab?"

Answer 11

Well, no…we would also need cat histones to form chromosomes, other (unknown) cat nuclear factors, and other (unknown) factors; cloning is actually really hard to do in most species

Answer 12

I never knew it was so complicated l0l

Answer 13

@aaronq @somy @jigglypuff314 @Rushwr @nincompoop @mathmale

Answer 14

@pooja195

Answer 15

I don't know what your looking for, I myself don't know how to explain what a "gene" is.

Answer 16

A gene is the basic physical and functional unit of heredity. Genes, which are made up of DNA, act as instructions to make molecules called proteins. In humans, genes vary in size from a few hundred DNA bases to more than 2 million bases.

Answer 17

@pink33
haha, did you read above? We still don't know what a gene is, now if your looking for a high school answer I guess that would work, otherwise it wouldn't lol.

Answer 18

so what should i put

Answer 19

high school or?

Answer 20

yea

Answer 21

if we continue with our cat example, "…but the only thing that makes a cat different from a person is the DNA sequence of its genes, right?"

Well, no…developmental timing of gene expression is very important in embryogenesis, and it’s fairly clear that many changes in gene expression that occur during development are not coded for by the developing organism’s genome, to say nothing of the fact that the cat’s genes (or any other animals genes) are more similar than dissimilar to our own.

Answer 22

"…but those things aside, knowing the DNA sequence in the nucleus of a cat will tell me all I need to know about the cat?"

…well, no, mitochondrial DNA and cell membrane that is inherited only through the mother, other nuclear factors including proteins that are specific to cats and required for development

Answer 23

"…but the DNA sequence for a gene is invariant within an organism, right?"

well, no…immune cells are constantly shuffling their genomes (jumping genes), and neurons have frequent chromosomal duplication and transposition events, and errors in DNA replication can introduce variation in any dividing cell

Answer 24

"…and genes code for the protein independently of the local chromosomal architecture?"

Well, no…epigenetic mechanisms can influence gene expression: histone acetylation, DNA methylation, and others

Answer 25

"…but at least we know that these epigenetic changes aren’t heritable, right?"

Well, no… they can be. There is good evidence that adult phenotypes can be heritable through means other than primary DNA sequence, and that brain region specific epigenetic modifications can be heritable.



So now...... what is a gene?................... LOL

Answer 26

I still have no idea what a gene is. good night

Answer 27

lololololololol ok, I think I might just go with a basic answer

Answer 28

lol alphadxg is right, it's complicated..but for all intents and purposes, you can go the "textbook definition" of a gene.

Answer 29

in simple terms you can say that : Gene is a portion of DNA that 'CAN' be transcribed AND translated into functional proteins needed by a cell.

In scientific terms the so called non functional portion of DNA takes up almost or around 98% of the entire DNA, so ofc it has some job to do and so its not at all useless. BUT the job it does is it regulates gene 'EXPRESSION' at any given time. Now the part the we call genes are the portions that code for a protein that can do something in cell, and since you need to regulate 'how much' of the protein you need, those 'non functional/coding' portions of the DNA along with other proteins that have regulatory functions will limit expression of that particular gene at that given time. So to put it simply the non functional portion is like a switch, that can turn the gene ON for it to be expressed and OFF to stop the expression (some physical changes are done to the shape of DNA a that time which you dont seem to be needing to know)

Lets give an example to show it in action:
Lets go to glucose and glycogen which is the storage form of glucose.
Now, when your cells need glucose, and they want to take it form the glycogen storage, they need certain enzymes to break it down right? Lets say ur cell is starving right now, it REALLY needs the glucose, and so it wants it RIGHT NOW - REAL FAST. I'll pause here for a sec

Lets come to human world, if you were given a job lets say to build a house, would it be faster for u to complete the task if you do it ALONE? or with lets say 20 more people?
Its quite clear that the more people do the work the faster this job will be done.

Now coming back to our glycogen, to break it down real fast, you need a lot of enzymes that do this task. So a signal is sent to your DNA, to the region where the genes for enzymes you need are located. They will sorta inform the regulatory region (nonfunctional region just before the gene) and be like 'hey, we need this gene that you are looking after to be transcribed now!' (ofc a suitable signal has to come, signal is basically another bunch of proteins that will come and inform as well as play role in 'switching the gene on and off' so its not as simple as im making it)

SO lets say it happened and the gene is now switched on so then it is transcribed and translated and now you have a lot of the enzymes you need to break down glycogen.
Now your cell took however much of glucose it needed, thats enough, so now we dont need anymore of those breaking down enzymes, so now we gotta switch the genes for those enzymes OFF to prevent their further expression since we dont need any more of it. And this is again done by that switch system and other proteins that help out in this.

Thats it, this is how regulation happens ' in simple ' terms.