* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Nucleic acid chemistry lecture 3
Community fingerprinting wikipedia , lookup
Peptide synthesis wikipedia , lookup
List of types of proteins wikipedia , lookup
Cre-Lox recombination wikipedia , lookup
Non-coding DNA wikipedia , lookup
Transcriptional regulation wikipedia , lookup
RNA interference wikipedia , lookup
Molecular evolution wikipedia , lookup
Silencer (genetics) wikipedia , lookup
Bottromycin wikipedia , lookup
RNA polymerase II holoenzyme wikipedia , lookup
Eukaryotic transcription wikipedia , lookup
Biochemistry wikipedia , lookup
Polyadenylation wikipedia , lookup
RNA silencing wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Messenger RNA wikipedia , lookup
Expanded genetic code wikipedia , lookup
Gene expression wikipedia , lookup
Deoxyribozyme wikipedia , lookup
Genetic code wikipedia , lookup
Non-coding RNA wikipedia , lookup
Nucleic Acid Chemistry Dr: Hussein abdelaziz Objectives By the end of lecture the student should: Differentiate between different types of RNA List differences between DNA and RNA Mention free nucleotides of biological impotances 3- RNA structure All RNA molecules are formed in the nucleus from the action of RNA polymerase on DNA template (transcription) transported to cytoplasm There are 3 main types of RNA (All are formed of one strand only) 1- messenger RNA = mRNA 2- transfer RNA = tRNA 3- ribosomal RNA = rRNA There are other types called small nuclear RNAs (snRNAs)(1 % of total RNA), about 30 species include ribozymes 1-mRNA Single strand formed complementary to template strand of DNA in the nucleus. 5% of total cellular RNA Variable in length Carry genetic codon (a message from DNA) for protein synthesis in the cytoplasm (in ribosomes) The sequence of the bases determines the sequence of the amino acids in the polypeptide chain Each 3 succcessive bases in mRNA are called genetic codon which codes for a specific amino acid 1st codon at 5' end called initiation codon & the last codon at 3' end called termination codon DNA mRNA Template strand 2-tRNA • 15% of total RNA • synthesized from template DNA • The smallest type of RNA (75-85 nucleotides) • It has anticodon arm that recognize genetic codon on mRNA and carry the corrospording AA at 3¯ terminal • When tRNA carries AA → it is said that → AA is activated → t RNA is charged 1. It is arranged in the form of a clover-leaf, presenting 3 loops (D-loop, pseudouridine loop and anticodon loop) & having 2 free ends (3', 5' ends) 2. 3' terminus has the terminal sequence CCA 3. The anticodon loop contains a triplet of nucleotides that can base pair with a codon on mRNA Common features of tRNA 4. Each codon of mRNA is read by a tRNA anticodon that can specifically base pair with it, then tRNA discharges it’s a.a for incorporation into growing polypeptide chain 5. There are at least 31 tRNA and 20 a.a. 6. The a.a is carried on 3' terminus 3-rRNA synthesized from template DNA in the nucleolus 80% of total RNA Ribosomes are large ribonucleoproteins found in the cytoplasm ( rRNA + protein ) & they are sites of protein synthesis from mRNA templates Mammalian Ribosomes has 2 subunits; large subunit (60S) & small subunit (40S) Whole is 80S ribosome Functions of ribosomes Responsible for protein synthesis from a.a carried by tRNA according to the information provided by mRNA. 1- In ribosomes, mRNA & tRNA interact to synthesize protein molecule 2- Ribosomes contain enzymes responsible for connecting the amino acids together in peptide linkage to form polypeptide chain Differences between DNA& RNA Site Function DNA RNA Nucleus & mitochondria Storage and transfer of genetic characters Cytoplasm mainly Protein biosynthesis Bases A, G, C and T A, G, C and U Sugar Deoxy- ribose Ribose Strands 2 strands =double helix One strand Types One type but 3 forms (A,B,Z) 4 types: mRNA,tRNA,rRNA, snRNA Free nucleotides of biological importance Base Form Function Adenine ADP & ATP Source of energy 3`,5` cAMP second messenger 3`-phosphoadenosinephosphosulfate (PAPS) sulfate donor S-adenosylmethionine (SAM) methyl donor Fatty acyl adenylates activate fatty acids Amino acyl adenylates activate amino acids GDP & GTP energy collection and protein synthesis 3`,5` cGMP metabolic regulator and antagonize cAMP GDP-Mannose, fucose glycoproteins & mucopolysaccharides synthesis. Hypoxanthine IDP & ITP Collection of energy & CO2 metabolism Uracil UDP metabolic carrier of glucose, glucuronic acid and galactose. Cytosine CDP carrier of choline, ethanolamine and diglyceride in phospholipid synthesis. Vitamin nucleotides riboflavin Synthesis of FMN & FAD Niacin Synthesis of NAD & NADP Pantothenic acid Synthesis of coenzyme A Vitamin B12 Synthesis of cobamide coenzyme Guanine