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DNA, Genes and Genomics

DNA, Genes and Genomics. Prokaryotic DNA. The prokaryotes usually have only one chromosome, and it bears little morphological resemblance to eukaryotic chromosomes. Consists of single, circular DNA molecule located in the nucleoid region of cell. Referred to as being “naked”

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DNA, Genes and Genomics

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  1. DNA, Genes and Genomics

  2. Prokaryotic DNA • The prokaryotes usually have only one chromosome, and it bears little morphological resemblance to eukaryotic chromosomes. • Consists of single, circular DNA molecule located in the nucleoid region of cell. Referred to as being “naked” • Bacterial cells may also contain multiple plasmids - small circular fragment of DNA separate from the main chromosome.

  3. Eukaryotic DNA Structure • DNA consists of two molecules that are arranged into a ladder-like structure called a Double Helix. • A molecule of DNA is made up of millions of tiny subunits called Nucleotides. • Each nucleotide consists of: • Phosphate group • Ribose sugar • Nitrogenous base

  4. Nucleotides Phosphate Nitrogenous Base Ribose Sugar

  5. Nucleotides • The phosphate and sugar form the backbone of the DNA molecule, whereas the bases form the “rungs”. • There are four types of nitrogenous bases.

  6. Nucleotides A T C Adenine Thymine G Guanine Cytosine

  7. Nucleotides • Each base will only bond with one other specific base. • Adenine (A) • Thymine (T) • Cytosine (C) • Guanine (G) Form a base pair. Form a base pair.

  8. DNA Structure A A T A T A T T Because of this complementary base pairing, the order of the bases in one strand determines the order of the bases in the other strand. C C C G G G

  9. DNA Replication • unfolding and unwinding of the DNA double helix at hundreds of points, known as replication origins, along the chromosome. • The enzyme helicase separates the two DNA strands, separating them like opening a zipper, with the point of opening being termed the replication fork. • Where the DNA strands are separated, a short length of RNA binds to each DNA strand under the control of the enzyme, DNA primase. This RNA acts as a primer (see figure 11.26a page 405).

  10. DNA Replication • A DNA polymerase enzyme can then proceed to build new DNA strands using each of the old strands as a template (see figure 11.26b). • Replication of DNA can occur only in the 5´ to 3´ direction. This is no problem with the so-called leading strand because its new complementary strand can be built continuously in the 5´ to 3´ direction. The other strand, known as the lagging strand, can be built only backwards and in short discontinuous pieces (Okasaki fragments - see figure 11.26b). • When finished, the RNA primers are removed, the gaps are filled by another DNA polymerase and the pieces are joined by the enzyme, DNA ligase.

  11. DNA Replication Watch DNAi clip

  12. Mitochondrial DNA • Mitochondria contain mtDNA,a double strandedcircular molecule comprising: • 16 568 base pairs and code for 37 genes: • 13 genes code for proteins that are involved in cellular respiration • 2 genes code for ribosomal RNA (rRNA) • 22 genes code for transfer RNAs (tRNAs).

  13. An individuals characteristics are determined by their DNA. The DNA determines which proteins are made. The most important proteins are enzymes. The sequence of bases in the DNA determines the sequence of amino acids in the protein. This is known as the GENETIC CODE. PROTEIN SYNTHESIS

  14. TRIPLET CODE 3 bases in the DNA code for one amino acid in the protein. Each triplet is known as a CODON. UNIVERSAL Found in all organisms. DEGENERATE More than one codon for each amino acid. NON-OVERLAPPING START AND STOP CODONS THE GENETIC CODE

  15. PROTEIN SYNTHESIS TRANSCRIPTION AMINO ACID ACTIVATION TRANSLATION

  16. Protein Synthesis Summary

  17. TRANSCRIPTION

  18. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  19. A U C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). G G G G T A C G G C T A A C A T A C A A T C

  20. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  21. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  22. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  23. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  24. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  25. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  26. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  27. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  28. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  29. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  30. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  31. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  32. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  33. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  34. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  35. U A C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  36. A U C C C A A A A A U U U U U U G HELICASE unwinds and unzips the relevant part of the DNA helix. RNA POLYMERASE attaches to the DNA. As RNA POLYMERASE moves along the sense strand, ribonucleotides are assembled in a precise order due to complementary base pairing (A <-> T/U ; G <-> C). One DNA strand acts as the template (SENSE STRAND), the other is redundant (ANTISENSE STRAND). G G G G T A C G G C T A A C A T A C A A T C

  37. U A C C A A A U U U U U U G Fully formed mRNA peels off the DNA and leaves the nucleus via a nuclear pore. The DNA rewinds. G G G G

  38. U A C C A A A U U U U U U G Fully formed mRNA peels off the DNA and leaves the nucleus via a nuclear pore. The DNA rewinds. G G G G

  39. U A C C A A A U U U U U U G G G G G

  40. U A C C A A A U U U U U U G G G G G

  41. AMINO ACID ACTIVATION

  42. C U A ACTIVATION OCCURS WHEN THE tRNA COMBINES WITH A SPECIFIC AMINO ACID THE ANTICODON DETERMINES WHICH SPECIFIC AMINO ACID IS ATTACHED

  43. TRANSLATION

  44. C U A A ribosome binds to the mRNA near the START CODON. C G G U U C A A A A U G C C G A U U G U A U G U U A G A A C

  45. C U A tRNA with the complementary ANTICODON (UAC) binds to the start codon (AUG) held in place by the large subunit of the ribosome. It brings with it the amino acid methione. U U C A A A A U G C C G A U U G U A U G U U A G A A C C G G

  46. C U A The ribosome now slides along the mRNA to “read” the next codon. U U C A A A A U G C C G A U U G U A U G U U A G A A C C G G

  47. C U A A second tRNA now bind to this codon, bringing a second amino acid with it. U U C A A A A U G C C G A U U G U A U G U U A G A A C C G G

  48. C U A A peptide bond is formed between the two amino acids. U U C A A A A U G C C G A U U G U A U G U U A G A A C C G G

  49. The tRNA which carried the first amino acid is released but leaves its amino acid behind as a DIPEPTIDE. U U C A A A C A U G C C G A U U G U A U G U U A G A U A A C C G G

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