Nucleotides, Nucleic Acids and Heredity
Nucleic Acids Introduction –Each cell has thousands of different proteins –Proteins made up from about 20 AA –Information for protein comes from parent organism - “heredity” –This information is contained in the chromosomes in the nucleus of the cell –Genes inside the chromosomes carry specific information
Genes Genes –Carry specific information regarding how to construct proteins –Lie in sequences along the chromosomes Genes are made up of Nuceic Acids: There are Two types of Nucelic Acids »DNA »RNA –The information that tells the cell which proteins to manufacture is carried in the molecules of DNA
Nucleic Acids Components of Nucleic Acids –RNA or ribonucleic acid »NOT found in chromosomes »6 types of RNA »polymeric nucleotides –DNA or deoxyribonucleic acid »present in chromosomes »polymeric nucleotides
Nucleic Acids Nucleotides are composed of: –a base –a sugar –a phosphate
Bases Bases found in DNA and RNA –All basic because they are heterocyclic amines –Uracil (U) found only in RNA –Thymine (T) found only in DNA DNA = A, G, C, T RNA = A, G, C, U
Bases Bases found in DNA and RNA Purines Pyrimidines
Sugars RNA contains D -ribose DNA contains D -deoxyribose Found in DNAFound in RNA CH 2 OH O HO D -ribose
Nucleosides Nucleoside = sugar + base A Nucleoside
Nucleosides Nucleoside = sugar + base A Nucleoside
Nucleosides Nucleoside = sugar + base A Nucleoside
Nucleosides Base + Sugar = Nucleoside AdenineAdenosine GuanineGuanosine ThymineThymidine CytosineCytidine UracilUridine
Phosphate AMP, ADP, ATP
Nucleotides BASESUGARPO 4 3- adenineribosemonophosphate
Nucleotides BASESUGARPO 4 3- adenineribosemonophosphate NucleoSIDE ugar adenosine
Nucleotides BASESUGARPO 4 3- adenineribosemonophosphate NucleoTIDE hree parts NucleoSIDE ugar adenosine adenosine monophosphate
Nucleotides Nucleoside + PO 4 3- = Nucleotide Adenosine Deoxyadenosine 5’-monophosphate (dAMP) Cytidine Deoxycytidine 5’-monophosphate (dCMP) Uridine (in RNA) Uridine 5’-monophosphate (UMP) - or - Thymidine (+ 2 PO 4 3- ) Deoxythymidine 5’-diphosphate (dTDP) Guanosine (+ 3 PO 4 3- ) Deoxyguanosine 5’-triphosphate (dGTP)
DNA - Primary Structure The primary structure is based on the sequence of nuclotides –1) The Backbone is made from Ribose (sugar) and Phosphate »PO 4 3- connected at Ribose 3’ and 5’ –2) The Bases (AGTC, AGUC) are side-chains and are what makes each monomer unit different. »Bases connected at Ribose 1’
DNA - Primary Structure
S P S P S P S P S P T G C A T Where: S = ribose P = phosphate G,T,A,C = bases
DNA - Primary Structure The order of the bases (-ATTGAC-) provides the primary structure of DNA. The backbone of both DNA and RNA consists of alternating sugar and phosphate groups –there is a 3’ end and a 5’ end –the backbone adds stability to the structure
DNA - Primary Structure Erwin Chargaff (1905- ) DNA always had ratios constant: moles adenine = moles thymine moles guanine = moles cytosine Base Pairing of: –A-T or T-A –G-C or C-G S P S P S P S P S P T G C A T
How we Depict DNA
DNA – Secondary Structure James Watson (1928- ) and Francis Crick ( ) Established 3-D structure of DNA Bases on adjacent strands PAIRED so that Hydrogen bonds formed: Complementary Base Pairing
DNA - Secondary Structure Complementary Base Pairing –Adenine pairs with Thymine –Position of H bonds and distance match
DNA - Secondary Structure Complementary Base Pairing –Guanine pairs with Cytosine –Position of H bonds and distance match
DNA - Secondary Structure Complementary Base Pairing
DNA - Secondary Structure DNA structure led to explanation of the transmission of heredity
DNA vs. RNA DNA and RNA differences: 1) DNA 4 bases AGCT RNA 4 basesAGCU 2)DNA sugardeoxyribose RNA sugarribose 3) DNA is almost always double stranded RNA is single stranded A pairs with U (not T)
DNA Replication Each gene is a section of DNA – base sequences –Each gene codes for 1 protein molecule –Each cell contains ALL of the info for the organism –Replication is the process of copying all genetic information on the DNA to new DNA
DNA Replication Steps 1. Opening of the superstructure 2. Relaxing the higher order structure 3. Unwinding the DNA double helix 4. Primer/Primase – initiate the replication 5. DNA polymerase – enzyme that adds the nucleotides to the chain – Pairing A-T G-C 6. Ligation – Joining of Okazaki fragments and completion of the molecule
DNA Replication View animations……… OumYo OumYo D1tus D1tus 8mIrI 8mIrI evZyg evZyg
DNA Replication Semiconservative Replication –The result is 4 strands of DNA –Only half of each helix is “new” –Semiconservative since one half of each new helix is a daughter strand and half a parent
DNA Replication
Okazaki fragments
DNA Replication Okazaki fragments
Types of RNA mRNA - Messenger RNA tRNA - Transfer RNA rRNA - Ribosomal RNA snRNA – Small nuclear RNA miRNA – Micro RNA siRNA – Small interfering RNA (1933)
mRNA Messenger RNA Carries info from DNA to cytoplasm Not stable (not long lasting) Info is for single protein synthesis Exactly complementary to one DNA strand
tRNA Transfer RNA (tRNA) Transfers amino acids to the point of protein synthesis Small (73-93 nucleotides) About 20 exist (one for each AA!) “L-shaped” Contain some “other” modified Nucleic Acids
Transfer RNA
rRNA Ribosomal RNA (rRNA) Found in ribosomes 35% protein, 65% rRNA make up ribosomes Large molecules with MW=1,000,000 Protein synthesis takes place on ribosomes
snRNA – Small nuclear RNA –Helps with the processing of the mRNA transcribed from DNA miRNA – Micro RNA –Important in the timing of organism development siRNA – Small interfering RNA –Help control Gene expression RNA
Transmission of Information Step 1 - Transcription –Copying the “code” from DNA to to mRNA –The mRNA then moves to the ribosome Step 2 - Translation –Deciphering the “code” from mRNA into protein –Each 3 nucleotides code for a specific AA Next Chapter Discussion!!!!!!!!!!
Transmission of Information SUMMARY DNA REPLICATION mRNA TRANSCRIPTION protein ! TRANSLATION amino acids