Central dogma
28
CENTRAL DOGMA BY : RISHAV DROLIA VIT UNIVERSITY
-
Upload
rishav-drolia -
Category
Education
-
view
248 -
download
1
Transcript of Central dogma
CENTRAL DOGMA
BY : RISHAV DROLIA VIT UNIVERSITY
CENTRAL DOGMA
“The central dogma of molecular biology is an explanation of the flow of genetic information within a biological system”
The central dogma of molecular biology deals with the detailed residue-by-residue transfer of sequential information. It states that such information cannot be transferred back from protein to either protein or nucleic acid.
-Francis Crick
Protein information cannot flow back to
nucleic acids
Fundamental framework to
understanding the transfer of sequence information between
biopolymers
DNA REPLICATION
DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. This process occurs in all living organisms and is the basis for biological inheritance
The double helix is unwound and each strand acts as a template (blue) for the next strand. Bases are matched to synthesize the new partner strands (green).
TRANSCRIPTION
Transcription is the process by which the information contained in a section of DNA is replicated in the form of a newly assembled piece of messenger RNA (mRNA).
Differs from DNA synthesis in that only one strand of DNA, the template strand, is used to make mRNA
Does not need a primer to start
Can involve multiple RNA polymerases
Divided into 3 stages:- -> Initiation -> Elongation -> Termination
TRANSCRIPTION: THE FINAL PRODUCT
TRANSLATION
The mRNA formed in transcription is transported out of the nucleus, into the cytoplasm, to the ribosome. Here, it directs protein synthesis. Messenger RNA is not directly involved in protein synthesis − transfer RNA (tRNA) is required for this. The process by which mRNA directs protein synthesis with the assistance of tRNA is called translation.
STEP : 1
tRNA molecules bind to the two binding sites of the ribosome, and by hydrogen bonding to the mRNA
STEP : 2
a peptide bond forms between the two amino acids to make a dipeptide, while the tRNA molecule is left uncharged
STEP : 3
the uncharged tRNA molecule leaves the ribosome, while the ribosome moves one codon to the right
Another tRNA molecule binds
STEP : 4
A peptide bond forms between the two amino acids to make a tripetide
STEP : 5
the uncharged tRNA molecule leaves the ribosome
STEP : 6
PROTEIN SYNTHESIS
Proteins are assembled from amino acids using information encoded in genes
The genetic code is a set of three-nucleotide sets called codons and each three-nucleotide combination designates an amino acid
Genes encoded in DNA are first transcribed into pre-messenger RNA (mRNA) by proteins such as RNA polymerase. Most organisms then process the pre-mRNA (also known as a primary transcript) using various forms of Post-transcriptional modification to form the mature mRNA, which is then used as a template for protein synthesis by the ribosome
The process of synthesizing a protein from an mRNA template is known as translation
1) BIOSYNTHESIS
The mRNA is loaded onto the ribosome and is read three nucleotides at a time by matching each codon to its base pairing anticodon located on a transfer RNA molecule, which carries the amino acid corresponding to the codon it recognizes
The enzyme amino acyl tRNA synthetises "charges" the tRNA molecules with the correct amino acids.
Proteins are always biosynthesized from N-terminus to C-terminus
2) CHEMICAL SYNTHESIS
Short proteins can also be synthesized chemically by a family of methods known as peptide synthesis, which rely on organic synthesis techniques such as chemical ligation to produce peptides in high yield
Chemical synthesis allows for the introduction of non-natural amino acids into polypeptide chains, such as attachment of fluorescent probes to amino acid side chains
Chemical synthesis is inefficient for polypeptides longer than about 300 amino acid
Most chemical synthesis methods proceed from C-terminus to N-terminus, opposite the biological reaction
GENE MUTATION
“A gene mutation is a permanent alteration in the DNA sequence that makes up a gene”
WHAT TYPES OF GENE MUTATIONS ARE POSSIBLE ?
1) Missense mutation
This type of mutation is a change in one DNA base pair that results in the substitution of one amino acid for another in the protein made by a gene.
2) Insertion
An insertion changes the number of DNA bases in a gene by adding a piece of DNA. As a result, the protein made by the gene may not function properly.
3) Deletion
A deletion changes the number of DNA bases by removing a piece of DNA
4) Duplication
A duplication consists of a piece of DNA that is abnormally copied one or more times. This type of mutation may alter the function of the resulting protein
5) Frame shift mutation
This type of mutation occurs when the addition or loss of DNA bases changes a gene's reading frame
A frame shift mutation shifts the grouping of these bases and changes the code for amino acids
Insertions, deletions, and duplications can all be frame shift mutations.
CHROMOSOME MUTATION
A Chromosome mutation is a missing, extra, or irregular portion of chromosomal DNA
Chromosome anomalies usually occur when there is an error in cell division following meiosis or mitosis.
TYPES OF CHROMOSOME MUTATIONS
Translocation: The joining of a fragmented chromosome to a non-homologous chromosome is a translocation. The piece of chromosome detaches from one chromosome and moves to a new position on another chromosome. Deletion: This mutation results from the breakage of a chromosome in which the genetic material becomes lost during cell division. The genetic material can break off from anywhere on the chromosome. Duplication: Duplications are produced when extra copies of genes are generated on a chromosome. Inversion: In an inversion, the broken chromosome segment is reversed and inserted back into the chromosome. If the inversion encompasses the centromere of the chromosome, it is called a pericentric inversion. If it involves the long or short arm of the chromosome and does not include the centromere, it is called a paracentric inversion. Isochromosome: This type of chromosome is produced by the improper division of the centromere. Isochromosomes contain either two short arms or two long arms. A typical chromosome contains one short arm and one long arm.
THANK YOU !
