DNA ORGANIZATION IN CHROMOSOME
Key vocabulary <ul><li>Nucleoid/ nucleosome </li></ul><ul><li>Chromatin  </li></ul><ul><li>Scaffold protein </li></ul><ul>...
Organization <ul><li>Highly dependent on the type of org. </li></ul><ul><li>Prokaryotic vs Eukaryotic org. </li></ul><ul><...
Precise location   Such a compact space. Question arises on how key activities in protein synthesis  can take place within...
Closer view..
Chromatin <ul><li>Chromosome discovered by W. Waldeyer. </li></ul><ul><li>Euchromatin   –Fibers less packed, disperse appe...
Chromosome number. <ul><li>Diff. org  = diff. no. </li></ul><ul><li>Man  23 pairs  =Total  46 . </li></ul><ul><li>22 pairs...
<ul><li>Varies among species. </li></ul><ul><li>Unrelated to the size or biological complexity of an org. </li></ul><ul><l...
G-bands <ul><li>Certain Tx/ staining techniques (Eg. Giemsa) will allow chromosomes to have striations. </li></ul><ul><li>...
Homologous pairs..
Homologous contd.. <ul><li>Notice that  the size, order of bands, and shape  is the same for both chromosomes.  </li></ul>...
Human chromosomes..
Human Karyotype Sex chromosomes
Chromosomes and genes.. <ul><li>The dark lines represent bands.  </li></ul><ul><li>Each chromosome, bears a particular set...
Typical metaphase chromosome <ul><li>i. Contains a  DNA replication origin </li></ul><ul><li>ii. A  centromere  to attach ...
Basic units of a chromosome <ul><li>i.   DNA  (2.2m = Massive folding + coiling) </li></ul><ul><li>ii.  Proteins  (Histone...
<ul><li>Complex between  histones + DNA = chromatin . </li></ul><ul><li>Nucleosome  = basic structure of chromatin (beaded...
Nucleosome.. <ul><li>Contains 200 bp DNA. </li></ul><ul><li>Subunit of chromatin composed of short DNA wrapped around hist...
Placement of genes   <ul><li>Gene = A region of DNA that  controls hereditary info  specifiying the sequence of a particul...
<ul><li>Color Blindness </li></ul><ul><li>Muscular Dystrophy </li></ul><ul><li>Fragile X syndrome </li></ul><ul><li>Hemoph...
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Gene And Chromosomes

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Gene And Chromosomes

  1. 1. DNA ORGANIZATION IN CHROMOSOME
  2. 2. Key vocabulary <ul><li>Nucleoid/ nucleosome </li></ul><ul><li>Chromatin </li></ul><ul><li>Scaffold protein </li></ul><ul><li>Histone/ non histone </li></ul><ul><li>Centromere </li></ul><ul><li>Telomere </li></ul><ul><li>Karyotyping </li></ul>
  3. 3. Organization <ul><li>Highly dependent on the type of org. </li></ul><ul><li>Prokaryotic vs Eukaryotic org. </li></ul><ul><li>Different technique used to visualise. </li></ul>
  4. 4. Precise location   Such a compact space. Question arises on how key activities in protein synthesis can take place within this limited space.
  5. 5. Closer view..
  6. 6. Chromatin <ul><li>Chromosome discovered by W. Waldeyer. </li></ul><ul><li>Euchromatin –Fibers less packed, disperse appearance occupying most of the nuclear region. </li></ul><ul><li>Heterochromatin- More dense area, found at centromeres. </li></ul>
  7. 7. Chromosome number. <ul><li>Diff. org = diff. no. </li></ul><ul><li>Man 23 pairs =Total 46 . </li></ul><ul><li>22 pairs of autosomes </li></ul><ul><li>2 sex chromosomes. </li></ul><ul><li>Cht. size shape + pattern , </li></ul><ul><li>Numbered in order of size. </li></ul><ul><li>Different cell diff number eg. Liver cells 92. </li></ul>
  8. 8. <ul><li>Varies among species. </li></ul><ul><li>Unrelated to the size or biological complexity of an org. </li></ul><ul><li>An asian deer = 3. </li></ul><ul><li>Diploid – 2 of the chromosome in a set. </li></ul><ul><li>Tetraploid – 4 of each chr. </li></ul><ul><li>Octaploid – 8 of each chr. </li></ul>
  9. 9. G-bands <ul><li>Certain Tx/ staining techniques (Eg. Giemsa) will allow chromosomes to have striations. </li></ul><ul><li>Large structures containing approx 10 7 bp DNA </li></ul><ul><li>chromosomes can be id by cht. banding pattern- Used for karyotyping – </li></ul><ul><li>Translocations can be id. by comparing to the original diploid set. </li></ul>
  10. 10. Homologous pairs..
  11. 11. Homologous contd.. <ul><li>Notice that the size, order of bands, and shape is the same for both chromosomes. </li></ul><ul><li>Carry the same genes in the same order. </li></ul>
  12. 12. Human chromosomes..
  13. 13. Human Karyotype Sex chromosomes
  14. 14. Chromosomes and genes.. <ul><li>The dark lines represent bands. </li></ul><ul><li>Each chromosome, bears a particular set of genes , these genes are arranged in a specific order. </li></ul>
  15. 15. Typical metaphase chromosome <ul><li>i. Contains a DNA replication origin </li></ul><ul><li>ii. A centromere to attach the DNA to the mitotic spindle. </li></ul><ul><li>iii. A telomere located at the end. </li></ul><ul><li>DNA needs to be condensed. </li></ul><ul><li>Chromosomes with AT/ GC base pair specific dyes. When stained. </li></ul><ul><li>Mitotic chromosomes have a banded structure </li></ul><ul><li>. ? Methaphase and not other stages? </li></ul>
  16. 16. Basic units of a chromosome <ul><li>i.   DNA (2.2m = Massive folding + coiling) </li></ul><ul><li>ii.  Proteins (Histones, scaffold p, polymerase) </li></ul><ul><li>iii.Small amounts of RNA . </li></ul>
  17. 17. <ul><li>Complex between histones + DNA = chromatin . </li></ul><ul><li>Nucleosome = basic structure of chromatin (beaded appearance) </li></ul><ul><li>Scaffold protein = non-histone p. Nucleosome coils aound it. </li></ul><ul><li>Polymerases = enzymes involved with </li></ul><ul><li>a) transcription of the gen. information during protein synthesis b) replication of the DNA prior to the division of chromosomes. </li></ul>
  18. 18. Nucleosome.. <ul><li>Contains 200 bp DNA. </li></ul><ul><li>Subunit of chromatin composed of short DNA wrapped around histone </li></ul><ul><li>8 histone molecules = octamer. </li></ul><ul><li>Nucleosome fibre is tightly coiled and looped around non-histone proteins </li></ul><ul><li>Nucleosomes are packed together = compact. </li></ul>
  19. 19. Placement of genes <ul><li>Gene = A region of DNA that controls hereditary info specifiying the sequence of a particular protein . </li></ul><ul><li>Carries biological info that must be copied and transmitted to its progeny. </li></ul><ul><li>Can be as short/long. </li></ul><ul><li>2001: 30,00/40,000 genes. </li></ul>
  20. 20. <ul><li>Color Blindness </li></ul><ul><li>Muscular Dystrophy </li></ul><ul><li>Fragile X syndrome </li></ul><ul><li>Hemophilia </li></ul>

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