Differences

This shows you the differences between two versions of the page.

--- chapter_06 [2025/02/22 23:19] – mike
+++ chapter_06 [2025/03/22 07:55] (current) – [Thinking about DNA and genes at scale] mike
@@ Line 88: / Line 88: @@
 The haploid human genome is approx. 3x10<sup>9</sup> bp in size. This means that the average human chromosome is $\frac{3\times10^9}{23}= 1.3 \times 10^8$ bp, or over one hundred million bp long – that is a very large molecule! Humans and most mammals have about 20,000 genes (which is surprisingly not that many more than Drosophila). This means that on average each human chromosome contains about 1000 genes. Genes are typically 10<sup>3</sup> - 10<sup>4</sup> base pairs in size, although they can be much larger.
-For example, the human dystrophin gene is 2 x 10<sup>6</sup> base pairs. Mutations in dystrophin result in a debilitating disease called Duchenne muscular dystrophy (DMD), which affects humans but also dogs, especially Golden Retrievers. Interestingly, DMD is a sex-linked trait in both humans and dogs - the dystrophin gene is on the $X$ chromosome in both species, and males are affected more than females (Fig. {{ref>Fig6}}. Note that not all of the DNA sequence of a gene may be coding sequence; that is, not all of the DNA sequence of a gene may correspond to codons for amino acids. In fact, most DNA is not gene coding sequence. Most eukaryotic genes (and in rare cases prokaryotic genes) contain DNA sequences called introns; when these intron sequences are transcribed into RNA they are removed from the transcript by a process called splicing (see [[chapter_12|Chapter 12]] for more details). However, the majority of DNA is non-coding sequence in between genes called intergenic regions.
+For example, the human dystrophin gene is 2 x 10<sup>6</sup> base pairs. Mutations in dystrophin result in a debilitating disease called Duchenne muscular dystrophy (DMD), which affects humans but also dogs, especially Golden Retrievers. Interestingly, DMD is a sex-linked trait in both humans and dogs - the dystrophin gene is on the $X$ chromosome in both species, and males are affected more than females (Fig. {{ref>Fig6}}). Note that not all of the DNA sequence of a gene may be coding sequence; that is, not all of the DNA sequence of a gene may correspond to codons for amino acids. In fact, most DNA is not gene coding sequence. Most eukaryotic genes (and in rare cases prokaryotic genes) contain DNA sequences called introns; when these intron sequences are transcribed into RNA they are removed from the transcript by a process called splicing (see [[chapter_12|Chapter 12]] for more details). However, the majority of DNA is non-coding sequence in between genes called intergenic regions.
 <figure Fig6>