07-07-2012, 12:13 PM
Gene Structure and Genome
Gene Structure .pptx (Size: 3.4 MB / Downloads: 40)
Molecular definition of a gene
In molecular terms, a gene commonly is defined as the entire nucleic acid sequence that is necessary for the synthesis of a functional gene product (polypeptide or RNA).
Prokaryotes
A Classical Operon: It is a functional unit of genomic material containing a cluster of genes under the control of a single promoter.
Clustered genes (operon) controlled by one promoter and transcribed as polycistronic mRNA and encode multiple gene products
Human genome facts
The following is a brief list of facts regarding the human genome. The human genome is the complete list of coded instructions needed to make a human.
The human genome is composed of more than 3 billion nucleotide bases. There are 4 types of nucleotide base: A- adenine, T- thymine, C- cytosine, G- guanine.
The order of the nucleotide bases contains the instructions for making an organism. Every three bases codes for an amino acid.There are 20 different amino acids that combined in different ways make different proteins.
The total number of human genes is estimated to be between 30,000 - 40,000.
Worms have 19,098 genes, fruit flies have 13,602 and yeast has 6,034.
Almost all nucleotide bases (99.9%) are exactly the same in all people.
Less than 2% of the genome codes for proteins.
The vast majority of the DNA in the genome (>97%) has no known function.
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