Size of the Genes:

 

The size the RNA or the protein it produces can roughly estimate size of the gene.  In general most of the rRNA, and tRNA, sn/sc RNA and mRNA genes are smaller than the size of precursors.   This holds good for both prokaryotes as well as eukaryote. The size, however, vary considerably from system to system and from one gene to another.  Interestingly, the size of a specific gene of one species is more or less same in another species, with certain exceptions.  But comparisons of certain gene from prokaryote with that of a eukaryote for the same gene show considerable variation, but the overall coding sequences show certain degree of similarity, again with certain exception and generalization between prokaryotes and eukaryotes cannot be made.  Actual size of the gene should take into the account of spacer region within the gene or non-coding regions in the gene; however, the size should include promoter and its related elements and terminal sequence elements.  Ultimately the size of the mRNA in prokaryotes is more or less equals to the size of the protein, so the size of the gene.  But the functional mRNA or the protein produced does not give the accurate size of the gene for in eukaryotes the size of the gene includes regulatory regions, introns and other non-coding regions.

 

 

Name of the Gene,

(only Few)

Size of the

gene (BP)

Size of Hn RNA

b Globin

1500

1382

Human insulin

1700

 

Rat insulin type II

1500

 

Protein kinase

11 000

 

Ovalbumin

8 000

7700

Serum albumin

25 000

 

 

 

 

Catalase

34 000

 

LDL receptor

45 000

 

Apolipoprotein

> 500 bp isoforms

 

Actin

1500

 

Clotting factor VIII

186 000

 

Thyroglobulin

300 000

 

Dystrophin

2.2-2.4 x10^6

79exons

Ovomucoid

~5.5-5.6kb

 

Alcohol dehydrogenase

 

 

Dihydrofolate- reductase

31 000

 

DMD, membrane protein

200-250kbp

 

Pyruvate kinase

12,142 bp

 

Rat fatty acid synthase

~18kbp

 

a Tropomycin (7 types)

~29,284 bases

 

Chick collagen 1a2

40 000

 

Fibronectin

75 000

 

Titin

38,138x3+200+ , 304,814bp

364exons

3816.30kDa a.a 4200kDa 244 domains

Ovalbumin

7.8 kb

 

CNTNAP2

2.3mb

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Human Gene count:

 

Data from ensemble; it indicates human genome contains 33399 genes?

                       

 

 

 

 

 

 

 

 

 

 

 

 

Lawerence A.moran-sandwalk

 

 

Number and Size of rRNA and tRNA Genes:

 

System

 5s RNA

 

tRNA

 

[16s/23/5s

18s/28s/5.8s]

 

Size in BP

Number

Per genome

Size in BP

Number per genome

Size in BP

Number

Per genome

E.coli

 

 

~5-7kbp

Operon

60

5.8 to 5.9kbp

7

Yeast

300kbp

140

Clusters

150-200bp

250-400

5.95KBP

140

D.melanogaster

300bp

 

165

Clusters

150-200bp

850

11.2 14.2kbp

250

X.laevis

300bp

24000

Clusters

150-200bp

1150

10.5 to13.5kbp

450-600

Mus musculus

300bp

200

 

 

12.5kbp

200

Homo sapien

300bp

1300-2000

150-200bp

1300-2000

13.7kbp

200

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Each of the genes as units has specific sizes, which is measured in terms of base pairs.  

 

The size varies from as small as 150 bp to 2,500,000 bp or longer.  The size just indicates the whole size, but it need not be represented in its RNA product base by base or its protein.

 

Comparing the exact size of the gene and the size of its final RNA, the size of the Gene is greater than its final RNA; sometimes it is several times the size of the final RNA.  The start and the end, with the exception of overlapping genes, delimit each gene.  

 

Average size of a prokaryotic gene is ~1000 ntds and that of a eukaryotic gene is ~1500 to ~2000 ntds.  At both ends of a gene there are noncoding sequences, actually the coding region lies in between the start codon and a terminator codon. 

 

In prokaryotes the mRNA transcript consists of individual cistrons one to many, each cistron code for a specific polypeptide chain. In polycistronic mRNAs spacer is found which helps in ribosomes dissociating from the mRNA and reassociating to initiate the chain.  But eukaryotic coding sequences are invariably interrupted with noncoding sequences called Introns; sometimes the total size of the intervening regions can be many times longer than the actual coding size. 

 

 

22: The Viruses - Biology LibreTexts

 

ssRNA_v2.jpg

Viral DNA

Bacterial

 

Coloured TEM of a plasmid of bacterial DNA - Stock Image - G110/0188 -  Science Photo Library

 

Plasmid DNA; PROFESSOR STANLEY COHEN / SCIENCE PHOTO LIBRARY

 

 

 

TMV

 

Plant Chromosome

 

Mitochondrial DNA Replication Group - Mitochondrial Genetic Diseases

 

 

Plant Cell - Definition, Structure, Function, Diagram & Types

Plant cell chloroplast hi-res stock photography and images - AlamyCD Genomics Unveils Chloroplast DNA (cpDNA) Sequencing Service for Your  Biological Research - LABinsights

 

 

Chromosome

 

Chromosomes Fact Sheet

Plant chromosome

 

 

Downloading human chromosome sequences - Omics tutorials

 

Chromosome - Wikipedia

 

Chromosome - Wikipedia

 

chromosome

 

Chapter 4: DNA, RNA, and the Human Genome – Chemistry

DNA,RNA