Question

1. You know that smoke from traditional cigarettes contains chemicals that can induce mutations. But what about e-cigarettes are they any safer than regular egarettes Describe how you would structure a study about electronic cigarettes and their effect on the incidence of lung cancer. Which type of study would be best case-controlled or randomized controlled? Forte A 2. Describe translation, induding where it takes place, the steps of the process, and the final products Portady For See BI A : 2. EE 3. Describe transcription, including when and where it occurs, the steps of the process, and the final products Start: 9:41 AM

Answer 1

The difference between e-cigarettes and regular cigarettes is that e-cigarettes do not contain tobacco. But e-cigarettes contain nicotine which is extracted from the tobacco and is addictive like regular cigarettes. According to the study e-cigarettes can cause cancer, mutation and other serious respiratory illness due to the toxic compounds it contain. E-cigarettes contain nicotine, flavours and other chemicals which vaporize and inhaled by the user, though it is less harmful than regular cigarettes but e-cigarettes are not safe. Case-controlled study is best because subjects are selected on the basis of whether they have a disease or not but in randomized controlled study there is no such selection.

TRANSCRIPTION Formation of RNA over DNA template is called transch NA template is called transcription. Out of two strand of DNA only one strand participates in transcription and called "Antisense strand If both strands act as a template during transcription they would code for wuring transcription they would code for RNA molecule with different sequence and if they code for proteins the sequence of aminoacid in e for proteins the sequence of aminoacid in these protein would be different and another reason that if the two RNA molecule produced they would be complementary to each other a they would be complementary to each other and form a ds RNA which prevent translation of RNA. A gene is defined as the functional unit of inheritance. It is difficult to literally define a gene in terms sequence, because the DNA sequence coding for tRNA or rRNA molecule is also define a gene (But Information of protein is present on the DNA segment which code mRNA. So generally it is reffered for it) ine segment of DNA which contains signal for the sunthesis of one polypeptide is known as "Cistron KINA polymerase enzyme is involved in transcription. In eukarvotes there are three types of RNA polymerases RNA polymerase-l for 28S rRNA, 18S rRNA, 5.8s rRNA synthesis. RNA polymerase-Il for m-RNA synthesis. RNA polymerase-III for t-RNA, 5S rRNA, SRNA synthesis. In eukaryotes RNA polymerase enzyme is made up of 10-15 polypeptide chains. Prokaryotes have only one type of RNA polymerase which synthesizes all types of RNAs. RNA polymerase (Core enzyme) of E. Coli has five polypeptide chains B. Ba, a ando. o polypeptide chain is also known as a factor (sigma factor). Core enzyne + Sigma factor = RNA polymerase (B. B. a, a, o) A transcription unit in DNA is defined primarily by the in three gigons in the DNA :- (1) A promoter, (ii) The structural gene (ll) A terminator Transcription start site Template strand Terminator Promoter Structural gene Coding strand

Following steps are present in transcription - (1) INITIATION :- DNA has a "Promoter site" where RNA polymerase binds and a "Terminator site" where transcrin stops Sigma factor (a) recognises the promoter site of DNA. With the help of sigma factor RNA polymerase enzyme attached to a specific site of DNA called "Promo site" In prokaryotes before the 10 N, base from "Starting point" a sequence of 6 base pairs (TATAAT) present on DNA, which is called "Pribnow box": In eukaryotes before the 20 N, base from "Starting point" a sequence of 7 base pairs (TATAAAA) OF (TATATAT) is present on DNA which is called "TATA box or Hogness box! At promoter site RNA polymerase enzyme breaks H-bonds between two DNA strands and separates them. One of them strand takes part in transcription. Transcription proceeds in 5' 3' direction. Ribonucleoside triphosphate come to lie opposite complementary nitrogen bases of anti sense strand. These Ribonucleotides present in the form of triphosphate ATP. GTP, UTP and CTP. When they are used in transcription, pyrophosphatase hydrolyse two phosphates from each activated nucleotide. This releases energy This energy is used in the process of transcription. (2) ELONGATION :- RNA polymerase enzyme establishes phosphodiester bond between adjacent ribonucleotides. - Sigma factor separates and core enzyme moves along the anti sense strand till it reaches terminator site. (3) TERMINATION :- When RNA polymerase enzyme reaches at terminator site, it separates from DNA templet. At terminator site on DNA, N, bases are present in palindromic sequence. In most cases RNA polymerase enzyme can recognise the 'Terminator site' and stop the synthesis of RNA chain, but in prokaryotes, it recognises the terminator site with the help of Rho factor (p factor). Rho (p) factor is a specific protein which helps RNA polymerase enzyme to recognise the terminator site. . . . . 5 DNA helix Promoter 98 RNA polymerase Intitiation Sigma factor : RNA CEB SWONEN-HONORED AND Elongation DOOOO RNA polymerase Termination RNA Rho factor NOTITIEVODOM Process of Transcription in Bacteria

SPLIT GENE Discovered by sharp and Roberts. They awarded by Nobel Prize in 1993. Gene which contains non functional part along with functional part is known as split gene. Non functional part is called Intron and functional part is called exon. By transcription split gene produces a RNA which contains coding and non coding sequence and called hn RNA (Hetero genous nuclear RNA). This hn RNA is unstable. Now 7 methyl guanonsine is added to its 5' end, and a cap like structure is formed. It is called capping and 200 nucleotides of adenylic acid are added to its 3' end, which is called poly 'A' tail, Now it becomes stable. By the process of RNA splicing hn-RNA produces functional m-RNA that is exonic RNA. In RNA splicing non coding parts is removed with the help of ribonuclease enzyme and coding part join together with the help of RNA ligase. Some specific proteins are also helpful in RNA-splicing called 'Small nuclear ribonucleoprotein' or 'SnRNP' or 'Snurps'. These SnRNP proteins combine with some other proteins and SnRNA to form spliceosome complex This spliceosome complex uses energy of ATP to cut the RNA, releases the non-coding part and joins the coding part to produce functional RNA. Non coding part of hn RNA remained inside the nucleus and not translated in to protein. Only coding part moves from nucleus to cytoplasm and translated into protein. Mostly Eukaryotic genes are example of split gene, but gene which forms histone and interferon protein are non split gene. It contains only and only exonic part. Mostly prokaryotic genes are example of non split gene. In euckaryotes after transcription splicing process also occured. The split gene represent an ancient (primitive) feature of gene. Presence of intron is a primitive character. The splicing process represent the dominance of RNA world. functional part Non functional part Functional part al part 5 = Antisense Strand of DNA Antie Exon Intron Exon Transcription Coding part Non coding part Coding part, part_3 = HnRNA(unstable) | Stabilization c Coding part end (AAA....) 3'end Poly A tail splic Coding part Non coding part Coding part Spliceosome Splicing 7mG cap complex ATP Ribonuclease Capping RNA lygase Tailing (by Poly A Polymerase by Guanyl transferase 7 HAAA.... Poly 'A' tail 7mG cap Send m-RNA

3D000 000 3' mRNA Capping Cap Intron 5. Op Exon Polyadenylation RNA splicing 5 ppp gree Poly Poly A tail -3 5. "Gupp Messenger RNA Process of Transcription in Eukaryotes

TRANSLATION (Protein Synthesis (1) Activation of Amino acid :- 20 types of amino acids participate in protein synthesis. Amino acid reacts with ATP to form "Amino acyl AMP enzyme complex 'Activated Amino acid'. which is also is also known (2) Amino acyl Amino acid + ATP Amino acyl AMP-enzyme complex + PP T-RNA synthetase This reaction is catalyzed by a specific 'Amino acyl t-RNA synthetase' enzyme. There is a separate 'Amino acyl t-RNA synthetase' enzyme for each kind of amino acid Charging of t-RNA (Loading of t-RNA) :- Specific activated amino acid is recognised by its specific t-RNA. Now amino acid attaches to the 'Amino acid attachment site' of its specific t-RNA and AMP and are separated from it. Amino acyl AMP-enzyme complex +t-RNA Amino acyl-RNA complex + AMP + enzyme MP and enzyme - (3) T, Amino acyl t-RNA complex is also called 'Charged t-RNA'. Now Amino acyl t-RNA moves to the ribosome for protein synthesis. Translation :- 3 steps - (A) Initiation of polypeptide chain :- In this step 30 's' and 50 's' sub units of ribosome, GTP. Mgt?, charged t-RNA, m-RNA ands initiation factors are required. In prokaryotes there are three initiation factors present - IF1, IF2, IF3. In Eukaryotes more than 3 initiation factors are present. Ten initiation factors have been identified in red blood cells - elF1, elF2, elF3, elF4A, elF4B, elF4C, elF4D, elF4F, elF5, elF6. Initiation factors are specific protein. GTP and initiation factors promote the initiation process. Both sub units of ribosome are separated with the help of IF3 factor. In prokaryotes with the help of "S D sequence" (Shine-Delgarno sequence) m-RNA recognise the smaller sub unit of ribosome. A sequence of 8 N, base is present before the 4-12 N. base o Initiation codon on mRNA, called "SD sequence". In Smaller subunit of ribosome, a complementary sequence of "SD sequence" is present on 16 'S rRNA, which is called "Anti Shine-Delgar sequence" (ASD sequence) -GENETICSVI GENE-ENG PA3 With the help of 'SD and ASD sequence' mRNA recognises the smaller sub unit of ribosome While in eukaryotes, smaller sub unit of ribosome is recognised by "7mG cap". In eukaryotes, 18 'S rRNA of smaller sub unit has a complementary sequence of "7mg cap OENGUSEO 30 'S' sub unit + m-RNA Ma 2 30 'S'm-RNA - complex NDEZ 2016 I S

This "30 'S' m-RNA - complex" reacts with 'Formyl methionyl t-RNA 'S' m-RNA - formyl methionyl t-RNA - complex" is formed. T part of m-RNA. A GTP molecule is required. 30 'S m-RNA - complex + Formyl methionyl t-RNA - complex Biology methionyl t-RNA - complex and "30 y t-RNA - complex" is formed. This t-RNA attaches with codon IF2, F3 GTP Mg 2 30 'S' m-RNA formyl methionyl t-RNA - complex Now larger sub unit of ribosome (50 'S' sub unit) joins this complex. The initiation factor ren and complete 70 'S ribosome is formed. In larger sub unit of ribosome there are three sites for t-RNA - 'P' site - Peptidyl site. 'A' site - Amino acyl site. 'E' site - Exit site Starting codon of m-RNA is near to 'P' site of ribosome, so t-RNA with formyl methionine amino acid first attaches to 'P' site of ribosome and next codon of m-RNA is near to 'A' site of ribosome. So next new tARNA with new amino acid always attach at 'A' site of ribosome but in initiation step 'A' site is empty. АА, AA TT TITTIT T3 (B) Fig. (1) Fig. (2) Chain - Elongation :- New tRNA with new amino acid is attaches at 'A' site of ribosome. The link between amino acid of 'P site of t-RNA is broken and t-RNA of P-site is discharged so - COOH of P-site A.A. becomes free. Now peptide bond takes place between - COOH group of P site amino acid and - NH, group of A-site amino acid. Peptidyl transferase enzyme induces the formation of peptide bond. In peptide bond formation, 23 'S' r-RNA is also helpful. This r-RNA acts as an enzyme so it is also called "Ribozyme". After formation of peptide bond t-RNA of P site released from ribosome via E-site and dipeptide attaches with A site. Now t-RNA of A site is transferred to P site and : A site becomes empty. Now ribosome slides over m-RNA strand in 5' 3' direction. Due to sliding of ribosome on m RNA, new codon of m-RNA continuously available at A site of ribosome and according to new codon of m-RNA new amino acid attaches in polypeptide chain. Translocase enzyme is helpful in movement of ribosome (translocation). GTP provides energy for sliding of ribosome. 59

e-Medical In elongation process some protein factors are also helpful, which are known as 'Elongation factor In prokaryotes three 'Elongation factors' are present - EF-Tu, EF-Ts, EF-G. In Eukaryotes two elongation factors are present - eEF1, eEF2. peptide bond | AA i AA AA, AA, AA, transloca- tion TTTT3 5 MTT AUG Fig. (3) Fig. (4) IT 13 5TTI AUG Fig. (5) CC) Chain - Termination :- Due to sliding of ribsome over m-RNA when any Nonsense codon (UAA, UAG, UGA) available at A site of ribosome, then polypeptide chain terminates. The linkage between the last t-RNA and the polypeptide chain is broken by three release factor called RF1, RF2, RF3 with the help of GTP. In eukaryotes only one Release Factor is known - eRF1. UA

An mRNA also have some additional sequences that are not translated and are referred as uncan (UTR). The UTRs are present at both 5'end (before start codon) and at 3'end (after stop The UTR(untranslated regions) present on mRNA are required, for efficient translation process the smaller subunit of ribosome by mRNA)