9/3/2009. DNA RNA Proteins. DNA Genetic program RNAs Ensure synthesis of proteins Proteins Ensure all cellular functions Carbohydrates (sugars) Energy

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1 Structure Properties Functions of the cell Chemical organization of the cell Based on molecular substrate : DNA contains information RNA ensures protein synthesis Proteins ensure vitality Relations between macromolecules in the cell Transcription Translation DNA RNA Proteins Carbohydrates Synthesis Lipids Functions of the main macromolecules in the cell DNA Genetic program RNAs Ensure synthesis of proteins Proteins Ensure all cellular functions Carbohydrates (sugars) Energy Lipids Cell membranes DNA RNA Characteristic location Nucleus, mitochondria Cytoplasm, nucleus, mitochondria Place of synthesis Nucleus, mitochondria Nucleus, mitochondria Proteins All cell s components Ribosomes Lipids Membranes Smooth ER Sugars Cytoplasm, membrane, nucleic acids Cytoplasm 1

2 Structure of macromolecules Primary structure A chain of monomers joined by covalent bonds Secondary structure Folding through hydrogen bonds Tertiary structure Three-dimensional (3-D) functional configuration of macromolecule based on hydrogen, hydrophobic, ionic, covalent bonds Quaternary structure, supramolecular A combination of some substances Structure of proteins Structure of the proteins Monomers 20 types of amino acids Primary a polypeptide chain of amino acids linked by peptide bond (the sequence of amino acids is determined by DNA) Secondary α-helixes and β-sheets Tertiary globular Quaternary some polypeptides and / or other molecules (nucleic acids, sugars, lipids) Peptide bonds Structure of proteins 2

3 Relationship: structure environment function Chemical structure primary Environment factors t o, ph, P, hν (light), etc. 3-D configuration conformation (shape) Properties Functions DNA Nucleic acids Single strand molecules; Contain genetic information RNA double-strand molecules: mrna copies information, template for protein synthesis trna transport of amino acids, translate genetic code rrna part of ribosomes, ensure protein synthesis microarn control of gene expression DNA deoxiribonucleicibonucleic acid Monomers Structure Primary Secondary Tertiary Location Properties Functions Synthesis Peculiarities of human DNA Methods of study Monomers nucleotides (dntp dnmp) Purine bases Adenine Guanine Pyrimidine bases Cytosine Thymine 3

4 Structure of DNA Primary structure Primary structure a polynucleotide chain, nucleotides connected by phosphodiester bonds Secondary structure a double helix = two helixes joined through hydrogen bonds Tertiary structure DNP = a deoxyribonucleoprotein 5' GCGT... 3 Primary structure = a polynucleotide chain of DNA Nucleotides are polymerized via phosphodiester bonds 3' 5'; Chain has direction 5' 3'; The order of nucleotides is randomized = genetic code; 5' AGTGCATACGTACGGACATT... 3 Writing of genetic information 5' 3 Reading of information 3 5 4

5 Secondary structure of DNA 5' A T G C A T A C G T A C G A T 3 3 T A C G T A T G C A T G C T A 5' Secondary structure of DNA Two polynucleotide chains joined via hydrogen bonds: Complimentary A T and G C; Antiparallel; Doublestranded helix; The quantity Pu = Py; A+G / T+C =1; The quantity A T and G C differs; Each turn in helix contains ~10 bp; The double helix may have different conformations: A, B, Z... Base complementarity ensures: Stability of DNA; Replication duplication of DNA; Transcription copying of DNA; Recombination; DNA repair 5

6 Types of DNA double helixes Tertiary structure DNA + proteins = DNP DNA + site specific proteins = functional comples Nuclear DNA + histones = chromatin chromosomes Properties of DNA Replication Repair Denaturation Renaturation Heterogeneity Flexibility Fragility Migration in electric field (DNA is ) Hybridisation Replication Functions of DNA Contains genetic information: About proteins About other macromolecules Transmits genetic information: 1DNA replication 2DNA Realization of genetic information DNA transcription RNA translation protein 6

7 Location of DNA In nucleus 95-98% Long linear molecules Associated with histones In interphase chromatin in division - chromosomes In mitochondria 2-5% Small circular molecules Peculiarities of human DNA Nuclear DNA (in somatic cells, diploid number of chromosomes) Length ~ 6,4x10 9 bp; 7 picograms 46 molecules; Associated with histones; heterogeneous: coding and non-coding sequences; repeated and unrepeated sequences; active and non-active sequences; stabile and instable ; Contains ~ pairs of genes; Replication takes place in S phase of cell cycle; 50% has maternal origin and 50% has paternal origin. Peculiarities of human DNA RNA ribonucleic acid Mitochondrial DNA Length 16,6 kb Ring molecules A number of identical molecules (2-10) Contains 37 genes There are no free spaces between genes Replication on cell demands Always has maternal origin Monomers NTP (ATP, GTP, CTP, UTP); Primary structure a polynucleotide chain; Secondary structure loops; Tertiary structure RNP (RNA+proteins) Monomers of RNA - NTP 7

8 Primary structure of RNA Polynucleotide chain 5 3' is synthesized: by polymerization of NTP through phosphodiester bonds 3 5 ; Using one strand of DNA as template; Transcription (=synthesis of RNA): Done by RNA-polymerase Complementarily Antiparallel;!!! All types of RNA are transcribed from DNA!!! RNA is complementary to one strand of DNA - is identical to the second strand of DNA Secondary structure of RNA Folding of polynucleotide chain: Loops obtained by complementary junction of bases from the same strand (A U şi G C) Each loop = functional site Number and conformation of loops is specific for each type of RNA mrna messenger RNA Single-stranded molecule There is a lot of types in the cell Represents a template for protein synthesis Each mrna contains information about synthesis of one or some polypeptide molecules In eukaryotes is produced as result of processing of a primary transcript (pro-mrna) trna transfer RNA Single-stranded molecules Contain unusual basis (thymine, pseudouridine, dihydrouridine) secondary structure based on complementary pairing of basis and formation of functional loops Ensure transfer of amino acids to the ribosome Represents the translator of genetic code In the cell may be present up to 61 types 8

9 rrna ribosomal RNA Single-stranded molecules Part of the ribosome In eukaryotes most types are prodused in nucleolus Ensures interaction between ribosomal subunits, trna and mrna during protein synthesis rrnas Secondary structure of rrna Types of the cells Prokaryotes Eukaryotes, nucleus Eukaryotes, mitochondrion Coefficient of sedimentation 5S 16S 23S 5S 5,8S 18S 28S 12S 16S 9