can you tell me what are exon and intron?

Question

and another question:are the exons more than introns?how many?one?and why?

i mean the number of them?which one is more?

Answer 1

well, to start, introns and extrons are part of a DNA sequence (usually for higher beings like us). they refer to regions of your DNA which will be encoded into useful proteins or cut off and thrown as trash tidbits for your cells to excrete. so which is which?

introns are the ones that get cut-off from the pre-mRNA sequence which will be used in transalation (the process where your cell makes proteins out of mRNA). in short, they are so useless during the transcription( the part where DNA is used as a mold to make RNA) and translation processes that they are called junk DNA.

exons are quite the opposite to introns. they are the ones that remain after all the introns are cut-off or "spliced-off" from the pre-mRNA sequence. technically, when you only have the exons left. it is already called the mRNA sequence ready for translation.

with regard to your second question: you can only tell when there are more intron than exons or vice versa depending on the species of organisms you may be referring to.

here is what i got from wikipedia.com:
Introns are sections of DNA colinear to the mRNA sequence that will be spliced out after transcription, but before the mRNA is translated. Introns are common in eukaryotic RNAs of all types, but are found in prokaryotic tRNA and rRNA genes only. The regions of a gene that remain in spliced mRNA are called exons. The number and length of introns varies widely among species and among genes within the same species. For example, the pufferfish Takifugu rubripes has little intronic DNA. Genes in mammals and flowering plants, on the other hand, often have numerous introns, which can be much longer than the nearby exons.

hope this helps.

Answer 2

Genomic DNA is a storage device containing information about the organism, in the form of coded messages called genes. Most of the coding serves as a recipe for various proteins that are built from amino acids, but there are also codes that influence things like when and how much of these proteins to build. When a protein needs to be built, the gene information from the DNA is used to make a copy in RNA, which is then used to build the protein. The DNA is the permanent copy, the RNA is the temporary disposable building plan, and the protein is the result.
That's the background.
Now, the RNA 'plan' details the code for the protein in a continuous string, but that information is stored in the DNA in chunks. Think of it like a computer storing a file to a hard drive - it puts a bit here, a bit there, and so forth. DNA isn't 'stored' like that, but the result is similar - A gene may be broken up into a bunch of pieces on the chromosomal DNA. When the DNA is copied into RNA, it only keeps the chunks of the gene, and leaves out the other pieces between them. The actual pieces of the gene in the DNA are called Exons, while the non-gene DNA chunks between the exons are called Introns.
As to whether there are more Exons than Introns, I really don't know. Probably. The exons tend to contain very similar DNA sequence between organisms (they're very similar between us, mice, cicadas, and trees, for some genes, for instance), while the introns vary a great deal between even fairly closely related organism. This would imply that the introns are not important, the organism doesn't put much effort into keeping the information accurate.

Answer 3

Introns are sections of DNA colinear to the mRNA sequence that will be spliced out after transcription, but before the mRNA is translated. Introns are common in eukaryotic RNAs of all types, but are found in prokaryotic tRNA and rRNA genes only. The regions of a gene that remain in spliced mRNA are called exonsgether constitute a gene..
An exon is any region of DNA within a gene that is transcribed to the final messenger RNA (mRNA) molecule, rather than being spliced out from the transcribed RNA molecule. Exons of many eukaryotic genes interleave with segments of non-coding DNA (introns). The term exon was coined by American biochemist Walter Gilbert in 1978:

Answer 4

Intron - removed (excised) regions of genetic material
Exons - the parts of the chromosome which are phisically transcibed, used. I don't know wha you mean by more, but there is more non-coding DNA than coding, this varies from species to species