Topic = Mechanisms for the implementation of genetic information and violations of these processes

1. SUBJECT :BIOCHEMISTRY
PREPAREDBY : HIMANSHUSAINI
COURSE : 2 YEAR

2. Topic = Mechanisms for the implementation
of genetic information and violations of
these processes

3. åThe implementation of genetic information occurs during the synthesis of protein
molecules using three types of RNA = informational (mRNA) (also called messenger
RNA, mRNA), transport (tRNA) and ribosomal (rRNA).
ågeneticists Beadle and Titum established that genes are responsible for the production
of enzymes that influence the development of a trait. And they put forward a hypothesis =
1 gene - 1 enzyme. Later, the hypothesis is interpreted as 1 gene - 1 polypeptide, a
section of a protein molecule. Later it was found that the characteristics of organisms are
formed under the influence of genes as a result of biochemical reactions.
(1)Mechanisms for the implementation of genetic information
åModern interpretation. Genetic information recorded in the form of a specific sequence
of nucleotides of a DNA molecule provides the synthesis of a specific protein-enzyme,
which catalyzes the course of a biochemical reaction resulting in a trait. The
manifestation of the action of a particular gene also depends on the environment and on
the action of other genes.
åDNA template to mRNAduring TRANDCRIPTION , and then the mRNA is used as a
template for the synthesis of proteins during TRANSLATION.

4. (1)Messenger RNA carrying information about the primary structure of protein molecules,
is synthesized in the nucleus. Having passed through the pores of the nuclear envelope,
i-RNA is directed to the ribosomes, where genetic information is deciphered - it is
translated from the “language” of nucleotides into the “language” of amino acids. The
amino acids from which proteins are synthesized are delivered to the ribosomes using
special RNAs called transport RNAs (t-RNAs).
(2)In t-RNA, the sequence of three nucleotides is complementary to the codon
nucleotides in i-RNA. Such a sequence of nucleotides in the structure of t-RNA is called
an anticodon. Each t-RNA attaches a certain, “its” amino acid, with the help of enzymes
and with the expense of ATP. This is the first stage of the synthesis. In order for an
amino acid to be incorporated into the protein chain, it must be detached from the t-RNA
(3)At the second stage of protein synthesis, t-RNA acts as a translator from the
“language” of nucleotides into the “language” of amino acids. This transfer takes place on
the ribosome. It has 2 regions: on one, t-RNA receives a command from i-RNA - the
anticodon recognizes the codon, on the other - the order is executed - the amino acid is
detached from the t-RNA.

5. åThe implementation of genetic information proceeds along the DNA - mRNA - protein
chain in two stages =
(1)translation
(2)transcription.
åThe universality of the genetic code and the similarity of the processes of the
implementation of genetic information confirm the unity of living nature. Thanks to the
mechanism of converting DNA information into protein, the regulation of biochemical
processes in the cell, its renewal and self-reproduction are controlled.
(1)Transcription.
åFor gene expression, i.e. synthesis of proteins encoded in it, the nucleotide sequence
of the coding DNA chain must be transformed into an amino acid sequence. Since DNA
is not directly involved in protein synthesis, the information stored in the nucleus must be
transferred to the ribosomes, where the biosynthesis of proteins is actually carried out.
åFor this, the corresponding region of the coding DNA strand is read (transcribed) with
the formation of a heterogeneous nuclear RNA [hnRNA (hnRNA)], that is, the sequence
of this RNA is complementary to the coding DNA strand . Since RNA contains uracil
instead of thymine .The AAG DNA triplet is transformed into the UUC codon hnRNA.

6. åRNA maturation. In eukaryotes, hnRNA, before leaving the nucleus in the form
of messenger RNA undergoes significant changes: excess (non-coding) regions (introns)
are cut out of the molecule, and both ends of the transcripts are modified by attaching
additional nucleotides

7. åThe mechanism of transformation of
genetic information is based on the
interaction of mRNA codons with transport
RNA [tRNA (tRNA), which transfers amino
acids linked to the 3'-end of tRNA to the
ribosome in accordance with the
information encoded in the mRNA. A triplet
(for example, GAA ) is located
approximately in the middle of the tRNA
strand , called an anticodon and is
complementary to the corresponding mRNA
codon a. If the UUC codon
is translated, then the anticodon in the Phe-
tRNA which carries the phenylalanine
residue at the 3'-end, interacts with
it . Thus, an amino acid residue occupies a
position in which a growing polypeptide
chain associated with a neighboring tRNA.

8. (2)Translation and transport of amino acids =
åThe main organic substances of all living organisms on Earth are proteins , and all
proteins are based on twenty amino acids . Each protein is a chain of amino acid
molecules. To "read" information from the mRNAs created at the previous stage, firstly, a
constant supply of amino acids is required, and secondly, work on transforming
the genetic codeinto amino acid
åThe fact is that each amino acid corresponds to a triplet of nucleotides, and this
correspondence is quite arbitrary. Therefore, there are always 20 types of so-called
transport RNA (tRNA) in the cell, which at one end have a chemical affinity for a certain
triplet of nucleotides, and at the other end a special enzyme (aminoacyl-tRNA
synthetase) attaches the corresponding amino acid to this triplet. That is, each such
tRNA is an adapter, and the set of synthetase molecules, which are also 20 types, is a
table for converting the genetic code into amino acid. tRNAs constantly "catch" amino
acids floating in the cytoplasm of cells and deliver them to the site of protein synthesis -
to the ribosomes. See Broadcast

10. (3)Synthesis (assembly) of proteins in ribosomes =
åRibosomes float in the cytoplasm of the cell and receive mRNA with
information from the nucleus and tRNA with material from the
surrounding cytoplasm.
åThe ribosome is also similar to a zipper, only much larger than RNA
polymerase and is a whole cellular organelle. During work, it is put on
the mRNA strand and slides over it.
åThe tRNA entering the ribosome binds to the current region of the
mRNA only if the response part corresponds to the encoded amino
acid. After that, the ribosome receives the required amino acid, detaches
it from the tRNA and connects it to the protein chain that it weaves.
åThe free tRNA is removed, and the ribosome moves on to the next
triplet of nucleotides, after which the process is repeated. It ends when
the entire mRNA chain has been traversed, while exactly the protein that
was encoded in that gene in DNA will be woven,

12. Genetic engineering techniques. =
åAccomplished using multiple techniques. There are a number of steps that are followed
before a genetically modified organism (GMO) is created. Genetic engineers must first
choose what gene they wish to insert, modify, or delete. The gene must then be isolated
and incorporated, along with other genetic elements, into a suitable vector. This vector is
then used to insert the gene into the host genome, creating a transgenic or edited
organism. The ability to genetically engineer organisms is built on years of research and
discovery on how genes function and how we can manipulate them. Important advances
included the discovery of restriction enzymes and DNA ligases and the development
of polymerase chain reaction and sequencing
åThis allowed the gene of interest to be isolated and then incorporated into a vector.
Often a promoter and terminator region was added as well as a selectable marker gene.
The gene may be modified further at this point to make it express more efficiently. This
vector is then inserted into the host organism's genome. For animals, the gene is
typically inserted into embryonic stem cells, while in plants it can be inserted into any
tissue that can be cultured into a fully developed plant.

13. åCommon techniques include microinjection, virus-
mediated, Agrobacterium-mediated or biolistics. Further tests are
carried out on the resulting organism to ensure stable
integration, inheritance and expression. First generation offspring
are heterozygous, requiring them to be inbred to create the
homozygous pattern necessary for stable inheritance. Homozygosity
must be confirmed in second generation specimens.
åTraditional techniques inserted the genes randomly into the host's genome.
Advances have allowed genes to be inserted at specific locations within a
genome, which reduces the unintended side effects of random insertion. Early
targeting systems relied on meganucleases and zinc finger nucleases. Since
2009 more accurate and easier systems to implement have been
developed. Transcription activator-like effector nucleases (TALENs) and
the Cas9-guideRNA system (adapted from CRISPR) are the two most
commonly used. They may potentially be useful in gene therapy and other
procedures that require accurate or high throughput targeting.

15. Violation of the genetic program of the cell and the mechanisms
åThe activation of pathological genes can be associated with structural changes in the
regulator genes, with the activation of lethal genes in homozygosity for autosomal
recessive genes or the manifestation of pathogenic genes associated with sex. In addition,
the manifestation of a pathogenic autosomal recessive trait may be associated with
another gene .
åThe introduction into the genome of a fragment of foreign DNA with pathogenic
properties , for example a virus, can lead to cell death or the persistence of the virus
inside it. This persistence often leads to malignant tumor growth. Under experimental
conditions, researchers introduce both pathological and missing genes into the cell
åAll of the above genomic disorders can be inherited if they arise in the germ cells, or
lead to somatic changes in the animal's body without inheritance (the genome is changed
in somatic cells).
åGenetic material can be changed so grossly that it becomes clearly visible even when
studying chromosomes using light microscopy during division. These are the so-called
genomic and chromosomal mutations.

16. åGenomic mutations lead to a gross change in the structure of the nuclear hereditary
material as a whole. They are accompanied by a change in the number and shape of
chromosomes, the ratio of their content in various cells. Genomic mutations are often
characterized by aneuploidy, heteroploidy, or polyploidy, which is often observed in
malignant tumor cells in violation of mitosis (with reduced mitosis). A genomic mutation
may be due to the fact that one of the chromosomes is represented not by two, as is usual
in a somatic cell, but by three or more copies. An example of such a mutation is Down
syndrome. Down syndrome in humans is caused by the translocation (attachment) .
ågene, or point, mutation is the replacement of individual nucleotides or small
sections of the genome within a single gene. The gene mutation is invisible during
histological examination, but changes the cell phenotype, which leads to the
formation of new traits in the cell and / or in the body as a whole.
Conformational mutations are distinguished when one nucleotide is replaced by
another with a change in the DNA double helix.
åmutation that does not make sense is a gene mutation that changes the structure
of a gene in such a way that reading information from it becomes impossible, or an
mRNA sequence is formed that cannot be translated.