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Genetic Coding in Cells

Genetic Coding in Cells. Double stranded Deoxyribose sugar Bases: C,G A,T Self replicate. Single stranded Ribose sugar Bases: C,G,A,U Can’t self replicate mRNA, tRNA, rRNA. DNA vs. RNA. Both contain a sugar, phosphate, and base. DNA Replication.

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Genetic Coding in Cells

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  1. Genetic Coding in Cells

  2. Double stranded Deoxyribose sugar Bases: C,G A,T Self replicate Single stranded Ribose sugar Bases: C,G,A,U Can’t self replicate mRNA, tRNA, rRNA DNA vs. RNA Both contain a sugar, phosphate, and base.

  3. DNA Replication • DNA divides in half by splitting down the center of the ladder starting at one end. • Each rung separates in the middle, between the 2 bases. C splits from G and A from T.

  4. DNA Replication cont. 3. The cell has spare DNA Units. 4. The correct DNA unit attaches itself to the appropriate rungs on each of the 2 half-ladders as the DNA molecule splits. A spare AT, a spare TA, a spare GC, & a spare CG. 5. After the DNA finishes “unzipping” and the spare DNA units join up with the rungs on the half ladders, 2 identical molecules are formed.

  5. Introduction to The Central Dogma of Molecular Biology

  6. Protein Synthesis Flow of Information: DNA RNA Proteins TranscriptionTranslation Transcription is the process by which a molecule of DNA is copied into a complementary strand of RNA. This is called messenger RNA (mRNA) because it acts as a messenger between DNA and the ribosomes where protein synthesisiscarried out.

  7. Transcription occurs in theNucleus. RNA polymerase (an enzyme) attaches to DNA at a special sequence that serves as a “start signal”. The DNA strands are separated and one strand serves as a template. The RNA bases attach to the complementary DNA template, thus synthesizing mRNA.

  8. Transcription cont. The RNA polymerase recognizes a termination site on the DNA molecule and releases the new pre - mRNA. Next the pre - mRNA under goes splicing. This is when the non-codingsequences or intronsare eliminated. The coding mRNA sequence can be described as an exon. Now the mature mRNA leaves the nucleus and travels to the ribosome in the cytoplasm.

  9. Transcription

  10. Translation Translationis the process of decoding a mRNA molecule into a polypeptide chain or protein. Each combination of 3 nucleotides on mRNA is called a codon or 3-letter code word. Each codon specifies a particular amino acid that is to be placed in the polypeptide chain (protein).

  11. Translation A three-letter code is used because there are 20 amino acids that are used to make proteins.

  12. OH NH2 P HO O Adenine N N O N N CH2 O B A S E S H O O Guanine P HO O N NH O SUGAR-PHOSPHATE BACKBONE N NH2 N CH2 O Arginine H O NH2 Adenine P HO O N N O N N CH2 O OH H A Codon

  13. Translation There is a total of 64 codons with mRNA, only 61 specify a particular amino acid. There are more than 1 codon for each of the 20 amino acids. The remaining three codons (UAA, UAG, & UGA) are stop codons, which signify the end of a polypeptide chain (protein). Besides selecting the amino acid methionine, the codon AUG also serves as the “initiator” codon, which starts the synthesis of a protein.

  14. Translation Transfer RNA (tRNA) Each tRNA molecule has 2 important sites of attachment. anticodon, binds to the codon on the mRNA molecule. The other site attaches to a particular amino acid. During protein synthesis, the anticodon of a tRNA molecule base pairswith the appropriate mRNA codon.

  15. Methionine A C C 73 1 72 2 71 3 70 4 69 5 68 6 67 59 7 66 Py A* U* 65 64 63 62 C 16 Pu 17 9 A Pu 17:1 13 12 Py 10 49 50 51 52 G C T y G* Py 22 23 Pu 25 47:16 G A 26 47:15 20 20:2 20:1 27 1 43 44 28 42 45 46 29 41 47 30 40 47:1 31 39 Py* 38 U Pu* U 34 36 C 35 A Anticodon Met-tRNA

  16. Translation Ribosome: Are made up of 2 subunits, a large one and a smaller one, each subunit contains ribosomal RNA (rRNA) & proteins. Protein synthesis starts when the two subunits bind to mRNA. The initiator codon AUG binds to the first anticodon of tRNA, signaling the start of aprotein.

  17. Protein Synthesis: Translation Ribosome: The anticodon of another tRNA binds to the next mRNA codon, bringing the 2nd amino acid to be placed in the protein. As each anticodon & codon bind together a peptide bondforms between the two amino acids.

  18. Protein Synthesis: Translation Ribosome: The protein chain continues to grow until a stop codonreaches the ribosome, which results in the release of the new protein and mRNA, completing the process of translation.

  19. Protein Synthesis: Translation

  20. fMet P A Large subunit E UAC 5’ GAG...CU-AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA-AT GCA...TAAAAAA 3’ mRNA Small subunit Translation - Initiation

  21. Polypeptide Arg Met Phe Leu Ser Aminoacyl tRNA Gly P A UCU Ribosome E CCA 5’ GAG...CU-AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA-AT GCA...TAAAAAA 3’ mRNA Translation - Elongation

  22. Polypeptide Met Phe Leu Ser Arg Gly P A Ribosome E CCA UCU 5’ GAG...CU-AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA-AT GCA...TAAAAAA 3’ mRNA Translation - Elongation Aminoacyl tRNA

  23. H O AMINE ACID Alanine Serine H N C OH H H O O C H N C OH H N C OH R H ANYTHING C C H H Amino Acid H H C C H H HO H H2O H H O O H N C N C OH C C H H H H C C H H HO H Protein Synthesis

  24. Polypeptide Met Phe Leu Ser Arg Gly P A Ribosome E CCA UCU 5’ GAG...CU-AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA-AT GCA...TAAAAAA 3’ mRNA Translation - Elongation

  25. Polypeptide Ala Met Phe Leu Ser Arg Aminoacyl tRNA Gly P A CGA Ribosome E CCA UCU 5’ GAG...CU-AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA-AT GCA...TAAAAAA 3’ mRNA Translation - Elongation

  26. Polypeptide Met Phe Leu Ser Arg Ala Gly P A Ribosome E CCA UCU CGA 5’ GAG...CU-AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA-AT GCA...TAAAAAA 3’ mRNA Translation - Elongation

  27. 5’ 3’ 3’ 5’ RNA Pol. Ribosome mRNA Ribosome 5’ Transcription And Translation In Prokaryotes

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