UNIVERSITATEA POLITEHNICA TIMISOARA

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UNIVERSITATEAPOLITEHNICA TIMISOARA

• MASTER SIIS
• Sisteme Informatice în Îngrijirea Sanata?ii

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www.medinfo.umft.ro/dim/bioinformatica.htm
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BIOINFORMATICA

• Prof Dr George I Mihalas
• UMF Victor Babes

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CURSUL 4

• BIOLOGIE CELULARA?I MOLECULARA

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Planul cursului

• Compozi?ia materiei vii
• Structura celulei
• Componente
• Membrana celulara structura, transport pasiv ?i
  activ
• Citoplasma
• Nucleul celular
• Organite celulare mitocondria, ribozomii
• Diviziunea celulara
• Mitoza
• Meioza
• Replicarea ADN
• Sinteza proteinelor
• Transcrip?ia
• Codul genetic, ARN de transport
• Transla?ia
• Controlul sintezei proteinelor
• Semnalizare (inter)celulara

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Structura celulei
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Structura celulei umane
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Structura celulei umane

• Membrana celulara
• Structura mozaic (Singer-Nicholson, 1972)
• Strat dublu fosfolopidic
• Proteine
• Intrinseci
• Traverseaza membrana
• Canale
• Pompe
• Partial inglobate
• receptori
• Extrinseci

• Memebrana
• Citoplasma
• Nucleu
• Organite celulare

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Membrana celulara (3-10 nm)
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Membrana celulara

• Structura fosfolipidelor
• Proprietatile fizice ale citoplasmei

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Membrana celulara
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Membrana celulara - rol

• Mentinere compozitie celulara
• Transport prin membrana
• Pasiv conform gradientului electrochimic
• Difuziune libera (gaze, subst. solubile în
  lipide)
• Difuziune facilitata cu transportor (ex.
  glucoza)
• Canale voltaj dependente / ligand dependente
• Canalul de Na, canalul de K
• Activ contra gradient (consum energetic)
• Primar Pompe ionice
• Secundar ionimolecule (simport, antiport)
• Endocitoza - exocitoza
• Sediul poten?ialului de membrana
• Semnalizare - transfer informatii
• Receptori
• Apoptoza

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Transportul pasiv prin canale ionice

• Canalele de Na ?i K
• 30-500 / µm2
• diam. 3-5 Å

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Structura canalelor ionice

• Canalul de potasiu

• Canalul de sodiu

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Poten?ialul de membrana
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Transport pasiv ?i activ
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Structura celulei umane

• Nucleu
• Membrana nucleara (în cont. RE)
• Nucleol
• Acizi nucleici
• ADN cromatina (cromozomi)
• ARN pe membrana nucleara
• Proteine nucleare
• Enzime
• Proteine de control

• Memebrana
• Citoplasma
• Nucleu
• Organite celulare

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Nucleu

• Ø 6 µm
• Stocheaza informatia
• Rol
• în diviziunea celulara
• în sinteza proteinelor

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Transportul prin membrana nucleara

• Pori molecule mici
• ARN, proteine transport activ (cargo GTP-aza)

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Structura celulei umane

• Organite celulare
• Reticulul endoplasmatic
• Ribozomi sinteza proteinelor
• Mitocondrii producere ATP
• Aparat Golgi
• Lizozomi
• Centrioli
• Microtubuli, microfilamente
• Vacuole, vezicule

• Memebrana
• Citoplasma
• Nucleu
• Organite celulare

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Mitocondria
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Mitocondria

• Pompa de protoni (teoria chemiosmotica)

1978, Peter Mitchell pr. Nobel in Chimie
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Structura celulei umane

• Organite celulare
• Reticulul endoplasmic
• Ribozomi sinteza proteinelor
• Mitocondrii producere ATP
• Aparat Golgi
• Lizozomi
• Centrioli
• Microtubuli, microfilamente
• Vacuole, vezicule

• Memebrana
• Citoplasma
• Nucleu
• Organite celulare

George Palade (1912 2008), pr. Nobel 1974
descoperirea ribozomilor
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Diviziunea celulara
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Diviziunea celulara

• Mitoza
• Celule somatice
• Diploide (2 x 23 cromozomi)
• Meioza
• Celulele sexuale
• Haploide (23 comozomi)

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Diviziunea celulara

• Mitoza
• Meioza

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Replicarea ADN
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Replicarea ADN
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(No Transcript)
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Sinteza proteinelor
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Mecanismul sintezei proteinelor

• Dogma centrala
• Transcriptia
• Translatia
• Codul genetic
• Pasii mecanismului de sinteza

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Sinteza proteinelor
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Transcriptia
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Transcriptia ARN polimeraza
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Codul genetic (codoni)20 AA ? 3 baze codon
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Mecanismul sintezei proteinelor
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Schema
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Tipuri de ARN
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Structura ribozomilor si a ARN-t
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Activarea aminoacizilor
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Translatia
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Sinteza proteinelor - pasi

• STEP 1 The first step in protein synthesis is
  the transcription of mRNA from a DNA gene in the
  nucleus. At some other prior time, the various
  other types of RNA have been synthesized using
  the appropriate DNA. The RNAs migrate from the
  nucleus into the cytoplasm.
• Prior to the beginning of the protein synthesis,
  all of the component parts are assembled in the
  ribosome which is the brown/tan structure in the
  left graphic.

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• STEP 2 Initiation
• In the cytoplasm, protein synthesis is actually
  initiated by the AUG codon on mRNA. The AUG codon
  signals both the interaction of the ribosome with
  m-RNA and also the tRNA with the anticodons
  (UAC). The tRNA which initiates the protein
  synthesis has N-formyl-methionine attached. The
  formyl group is really formic acid converted to
  an amide using the -NH2 group on methionine (left
  most graphic)
• The next step is for a second tRNA to approach
  the mRNA (codon - CCG). This is the code for
  proline. The anticodon of the proline tRNA which
  reads this is GGC. The final process is to start
  growing peptide chain by having amine of proline
  to bond to the carboxyl acid group of methinone
  (met) in order to elongate the peptide.

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• STEP 3 Elongation
• Elongation of the peptide begins as various
  tRNA's read the next codon. In the example on the
  left the next tRNA to read the mRNA is tyrosine.
  When the correct match with the anticodons of a
  tRNA has been found, the tyrosine forms a peptide
  bond with the growing peptide chain .
• The proline is now hydrolyzed from the tRNA. The
  proline tRNA now moves away from the ribosome and
  back into the cytoplasm to reattach another
  proline amino acid.

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• Step 4 Elongation and Termination
• When the stop signal on mRNA is reached, the
  protein synthesis is terminated. The last amino
  acid is hydrolyzed from its t-RNA.
• The peptide chain leaves the ribosome. The
  N-formyl-methionine that was used to initiate the
  protein synthesis is also hydrolyzed from the
  completed peptide at this time.
• The ribosome is now ready to repeat the synthesis
  several more times.

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Schema evenimente in Sinteza Proteinelor
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Controlul sintezei proteinelorTeoria Jacob-Monod
(operon), Nobel 1965

• Gene de control
• g. operatoare
• g. regulatoare
• Feedback negativ
• lactoza inductor
• Mecanism de reglare
• Model valabil la procariote

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Controlul sintezei proteinelorModele cu feedback
pozitiv

• Introni si exoni
• (exonii exprima prot)
• Starea normala
• Gena silent
• Initierea sintezei
• Exon shuffling

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Semnalizare celulara

• G proteins are important signal transducing
  molecules in cells
• The human genome encodes roughly 950 G
  protein-coupled receptors
• Approximately 150 of the GPCRs found in the human
  genome have unknown functions

• Alfred Gilman Martin Rodbell pr. Nobel 1994
  proteina G

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PAUZA