The larger the chromosome the more genes?

Question

or do they have the same number of genes? What makes up their size?

Answer 1

A gene is part of a DNA molecule within the nucleus of all cells. Each gene codes for a particular protein. Thus a gene is a unit of the inheritable characteristics of the organism. Humans have tens of thousands of different genes; these determine the phenotype of the individual. On the other hand chromosomes atre a threadlike linear strand of DNA and associated proteins in the nucleus of eukaryotic cells that carries the genes and functions in the transmission of hereditary information. Neither of which are related as to the number

Answer 2

There is no linear relationship between gene count and a chromosome's length. Some chromosomes have many more genes than others. Thus they have different densities of genes. However do not think that because there are fewer protein-coding segments that the rest does nothing. The expression of all genes is highly regulated and these intervening, unexpressed regions  are likely to be needed to control when, where and how much transcription occurs in the coding regions. Control mechanisms differ so some like enhancers are not even near the genes they influence. Other regulatory sequences are found abutting coding sequences. Not all genes express in all cells so many must be silenced in each cell type that does not use them.

Chromosome 1 is the largest of our chromosomes, of this  about 99% is now sequenced. Computer analysis is used to look for open reading frames (genes). The difficulty is there are many defunct genes that never expressed, or no longer express. These are called pseudogenes. So far researchers have counted 3,141 gene structures and 991 pseudogenes on about 224Mb. ~14 genes/Mb

http://www.sanger.ac.uk/HGP/Chr1/

Chromosome 13  seems to have the lowest density, of the autosomes  analyzed, with 633 gene structures and 296 pseudogenes in ~114Mb. ~5.5 genes/Mb

Then chromosome 19 has the highest density of the autosomes. In 64Mb has so far identified  1,461 genes and 321 pseudogenes. ~23genes/Mb

http://www.sanger.ac.uk/HGP/Chr13/

Chromosome 21 is our shortest at 47Mb. This gene has 271 genes (243 are identified genes) with 87 pseudogenes

~5.8 genes/Mb

http://may2005.archive.ensembl.org/Homo_...

Pseudogenes have some sequence features that resemble  protein coding open reading frames but lack some critical element that would allow a functional transcription/translation to produce a protein. Some do produce RNA that is not translated. It is not known if all have a function but a few have been found. http://www.scienceblog.com/community/old...

Answer 3

hmm i never new there was large and small chromosomes..

Answer 4

Not necessarily. Chromosomes are not just made of genes, they also have intervening sequences of DNA between genes. Large chromosomes may (or may not) have more of these intervening segments, thus making them larger, or they may have more genes. There is no universal answer.