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DNA, GENE AND CHROMOSOME

DNA, GENE AND CHROMOSOME. By khalid el jendi Molecular genetics specalist. What is a gene?. A characteristic passed onto an organism (inherited) by its parents Genetic inheritance The entire nucleic acid sequence that is necessary for the synthesis of a functional protein and RNA.

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DNA, GENE AND CHROMOSOME

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  1. DNA, GENE AND CHROMOSOME By khalid el jendi Molecular genetics specalist

  2. What is a gene? • A characteristic passed onto an organism (inherited) by its parents • Genetic inheritance • The entire nucleic acid sequence that is necessary for the synthesis of a functional protein and RNA. • There are also tRNA and rRNA genes

  3. What molecule transmits genetic inheritance from parents to offspring? What is the unit of heredity • DNA (deoxyribonucleic acid)

  4. What is the Genes? Genes is genetic instructions coded for by DNA that transmits genetic inheritance from parents to offspring

  5. DNA Transcription rRNA mRNA tRNA ribosome Translation Protein Central Dogma & New Dogma of Genetic Material Information flow: 1. Central Dogmaof molecular genetic 2.New dogmaof molecular genetics

  6. What is DNA? A DNA molecule consists of two complementary chains of nucleotides The structure of DNA provides a mechanism for heredity

  7. The discovery of the double-helical structure of DNA By Watson-Crick, in 1953 is a landmark event.

  8. DNA Structure DNA is double stranded DNA strands are antiparallel G-C pairs have 3 hydrogen bonds A-T pairs have 2 hydrogen bonds One strand is the complement of the other Major and minor grooves present different surfaces 7. Almost all cellular DNA is B-DNA 8. B-DNA has ~10.5 bp/turn of the helix

  9. Where genes located? • In the chromosome in the nucleus of a cell

  10. The Structure of Chromosome • Nucleotides --> DNA --> Gene --> Chromosome • Human DNA is ~ 2 meters long. The nucleus of DNA is about 6 µM in diameter. So, how the very long DNA pack into a very small nucleus?

  11. Cell, chromosome and gene (DNA) The body contains trillions of cells chromatin Nucleus (center of cell) contains chromosomes and genes A gene, a segment of DNA (spiraled double chain) containing the hereditary code Chromosomes are threadlike structures composed of DNA molecules

  12. Chromosome rearrangement

  13. Structural Organization of Nucleosome Nucleosome structure

  14. How does a gene (DNA) expressed into a certain character?

  15. Gene Expression in Eukaryotes and Prokaryotes

  16. Molecular Definition of Gene • The entire nucleic acid sequence that is necessary for the synthesis of a functional protein and RNA • Coding region (exon and intron) + Regulatory sequences (e.g. promotor, enhancer, polyadenylation site, splicing sites)

  17. Basic Gene Structures • Eukaryotic genes • Coding region/exon, and intron, • Regulatory sequences e.g. promotor, enhancer, polyadenylation site, splicing sites • translation starts and stops

  18. X-gene promoter Y-gene Z-gene start stop start stop start stop Basic Gene Structure • Prokaryotic genes • coding regions, non-coding regions • translation starts and stops Prokaryotic genes are easier to identify than eukaryotic genes because of the simplicity of their gene structure and the density of genes in the genome

  19. Prokaryotes (intronless protein coding genes) Upstream (5’) Downstream (3’) promoter TAC Gene region DNA Transcription (gene is encoded on minus strand .. And the reverse complement is read into mRNA) ATG mRNA 5´ UTR 3´ UTR CoDing Sequence (CDS) ATG Translation: tRNA read off each codons, 3 bases at a time, starting at start codon until it reaches a STOP codon. protein

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