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Gene structure and gene expression
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Control region
(leader sequence) |
Central coding region |
Control region
(trailer) |
Gene structure:schematic represntation
Genes: structure and expression:
The control
region regulates the half-life of the mRNA or controlling the
translation.
The central
region is composed of alternating sequences of coding sequences
(exons) and non-coding sequences (introns).
Gene family
is a set of genes whose exons are related.
Gene cluster
is a group of related genes that are adjacent to each other.
The flow of
the genetic information:
The flow of
genetic information occurs through the process of transcription
and translation.
•
Transcription is the transfer of the genetic information from
DNA into RNA by the aid of an enzyme known as polymerase.
DNA → RNA.
•
Translation
is the transfer of the genetic information carried
by the RNA into protein.
•
Protein synthesis:
RNA → Protein.
Worth noting that some viruses transfer the genetic information
from DNA into RNA. This is the by the aid of an enzyme known as
reverse transcriptase.
Notes:
DNA
Double
stranded polymer (helix) of polynucleotide chains.
Bind
together by hydrogen bonds between the bases of the nucleotides
in complementary manner. A=T and GΞC.
The two
strands run antiparallel (in opposite direction). Thus one of
them is running in the 5` to the 3` direction, and the other
runs in the direction of the 3` to the 5` direction.
Note that
transcription (reading the genetic code) occurs in the direction
of the 5` to the 3` direction.
RNA
It is
transcribed form the DNA into the form of a single strand
polymer of nucleotide.
The
pyrimidine Uracil replaces the thymine in DNA.
The pentose
sugar is ribose.
It is less
stable than DNA.
There are
four main types: messenger mRNA, transfer tRNA, and ribosomal
rRNA
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