Scientific End of  Men..? By Prof.S.Mohana, Tamil Nadu Science Forum.
Cell & chromosomes <ul><li>There are 46 chromosomes in the nucleus of our  body cells . </li></ul><ul><li>Of these, 23 fro...
Cells  <ul><li>The largest and smallest cells in the human body are the gametes, or the sex cells.  </li></ul><ul><li>The ...
Cell, chromosome & gene
Number of Human Cells <ul><li>  the average adult human body is made up of &quot;50 million million&quot; (50 trillion) ce...
 
Chromosomes  <ul><li>Genes are packaged in bundles called chromosomes.  </li></ul><ul><li>Humans have 23 pairs of chromoso...
Human chromosome <ul><li>22.pairs of  autosomes </li></ul><ul><li>1 pair of allosomes or sex chromosomes </li></ul>
Chromosome- structure
DNA
Autosomes  & allosomes
Sex chromosomes <ul><li>There are also two chromosomes that have been given </li></ul><ul><li>the letters X and Y: these a...
Female and Male children <ul><li>XX-Female  XY- Male </li></ul>
Human chromosomes
 
Human Y chromosome
Human Y chromosome <ul><li>In humans, the Y chromosome spans 58 million  base pairs  (the building blocks of  DNA )  </li>...
Character of Y <ul><li>The human Y chromosome is unable to recombine with the X chromosome, except for small pieces of  ps...
Chromosomes
Origin of chromosomes <ul><li>The mammalian sex chromosomes are thought to have arisen from an ordinary pair of autosomes ...
Our life
Our life <ul><li>All of the 20,000 or so genes contain a different `packet’ of information necessary for our bodies to gro...
Our life
Genes  <ul><li>Each of these beads is called a  gene </li></ul><ul><li>Each gene is a piece of genetic information </li></...
Human Genome <ul><li>The human genome is a complete copy of the entire set of human gene instructions.  </li></ul><ul><li>...
Number of Genes <ul><li>Our genes have an important role in our cells </li></ul><ul><li>Each gene has its own specific loc...
Chromosomes & genes
Gene <ul><li>A gene is a distinct portion of a cell’s DNA. Genes are coded instructions for making everything the body nee...
Gene  <ul><li>Our genes have an important role in our cells </li></ul><ul><li>Each gene has its own specific location on t...
DNA- Information <ul><li>The DNA code is made up of very long chains of four chemical ‘letters’:  A denine (A),  G uanine ...
DNA <ul><li>–  </li></ul><ul><li>Different genes are active in different cell types, tissues and organs, producing the nec...
Human chromosomes
Human Chrosomes  - crossing over
Human XY chromosomes
Human sex chromosomes <ul><li>XX & XY  </li></ul>
Human sex chromosoms
XY
Mutation <ul><li>The particular order of the pairs of As, Ts, Cs, and Gs is extremely important in the DNA. Sometimes ther...
Y Chromosomes evolution in Animals
Y is declining
Degeneration of Y <ul><li>Both sex chromosomes have the same origin  evolutionary mechanisms which allowed the Y chromosom...
Dunnart – marsupial..4 genes
Degeneration of Y-why? <ul><li>when woman (XX) can freely choose a man (XY) as a partner for reproduction from the whole p...
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Chromosomes 221009

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Chromosomes 221009

  1. 1. Scientific End of Men..? By Prof.S.Mohana, Tamil Nadu Science Forum.
  2. 2. Cell & chromosomes <ul><li>There are 46 chromosomes in the nucleus of our body cells . </li></ul><ul><li>Of these, 23 from our mother’s egg and 23 from </li></ul><ul><li>father’s sperm </li></ul><ul><li>When the egg and the sperm join together at time of conception, they form the first cell of the baby </li></ul><ul><li>The baby’s body cells now have 46 chromosomes, made up of 23 pairs, just like the parents </li></ul>
  3. 3. Cells <ul><li>The largest and smallest cells in the human body are the gametes, or the sex cells. </li></ul><ul><li>The female sex cell, the oocyte, is about 35 microns in diameter, which puts it just on the edge of being visible if you have real good eyes. </li></ul><ul><li>The male sex cell, spermatozoan, cell is only about 3 microns in diameter, and therefore is the smallest cell of the human body.  </li></ul>
  4. 4. Cell, chromosome & gene
  5. 5. Number of Human Cells <ul><li>  the average adult human body is made up of &quot;50 million million&quot; (50 trillion) cells, </li></ul>There are approximately 30 trillion Red Blood Cells, 2 trillion Platelets, and 500 million White Blood Cells in your Circulatory System. In Lymph system, another trillion lymphocytes and immune related cells. a total of about 38-40 trillion cells. Naturally, most of the MASS in the body is comprised by the 4 trillion cells that make up your solid tissues, especially your muscle and skeletal cells.
  6. 7. Chromosomes <ul><li>Genes are packaged in bundles called chromosomes. </li></ul><ul><li>Humans have 23 pairs of chromosomes (for a total of 46). </li></ul><ul><li>Of those, 1 pair is the sex chromosomes (determines whether you are male or female, plus some other body characteristics), and the other 22 pairs are autosomal chromosomes </li></ul>
  7. 8. Human chromosome <ul><li>22.pairs of autosomes </li></ul><ul><li>1 pair of allosomes or sex chromosomes </li></ul>
  8. 9. Chromosome- structure
  9. 10. DNA
  10. 11. Autosomes & allosomes
  11. 12. Sex chromosomes <ul><li>There are also two chromosomes that have been given </li></ul><ul><li>the letters X and Y: these are the sex chromosomes . The X </li></ul><ul><li>chromosome is much larger than the Y chromosome. </li></ul><ul><li>Women have• 46 chromosomes (44 autosomes plus two copies of the X chromosome) in their body cells: 46,XX </li></ul><ul><li>• 23 chromosomes (22 autosomes plus an X chromosome) in </li></ul><ul><li>their egg cells </li></ul><ul><li>Men have• 46 chromosomes (44 autosomes plus an X and a Y </li></ul><ul><li>chromosome) in their body cells: 46,XY </li></ul><ul><li>• 23 chromosomes (22 autosomes plus an X or Y chromosome) </li></ul><ul><li>in their sperm cells </li></ul>
  12. 13. Female and Male children <ul><li>XX-Female XY- Male </li></ul>
  13. 14. Human chromosomes
  14. 16. Human Y chromosome
  15. 17. Human Y chromosome <ul><li>In humans, the Y chromosome spans 58 million  base pairs  (the building blocks of  DNA ) </li></ul><ul><li>.Represents approximately 0.38% of the total DNA in a human  cell . </li></ul><ul><li>The human Y chromosome contains 86 [8]  genes, which code for only 23 distinct proteins. </li></ul><ul><li>Traits that are inherited via the Y chromosome are called holandric traits </li></ul>
  16. 18. Character of Y <ul><li>The human Y chromosome is unable to recombine with the X chromosome, except for small pieces of pseudoautosomal regions  at the  telomeres  (which comprise about 5% of the chromosome's length). </li></ul><ul><li>These regions are relics of ancient  homology  between the X and Y chromosomes. </li></ul><ul><li>The bulk of the Y chromosome which does not recombine is called the &quot;NRY&quot; or non-recombining region of the Y chromosome </li></ul><ul><li>  It is the  SNPs  in this region which are used for tracing direct paternal ancestral lines </li></ul>
  17. 19. Chromosomes
  18. 20. Origin of chromosomes <ul><li>The mammalian sex chromosomes are thought to have arisen from an ordinary pair of autosomes ~300 million years ago. </li></ul><ul><li>Until then, ambient temperature during embryonic development might have determined the sex of mammalian ancestors, as in many modern reptiles and other descendants of bony fish. </li></ul><ul><li>The foremost sex chromosome bearers are, notably, birds and mammals. </li></ul>
  19. 21. Our life
  20. 22. Our life <ul><li>All of the 20,000 or so genes contain a different `packet’ of information necessary for our bodies to grow and work. </li></ul><ul><li>Our genes also contain the information for how we look: the colour of our eyes, how tall we are, the shape of our nose, etc. </li></ul><ul><li>The information is in the form of a chemical (DNA) code (the genetic code </li></ul>
  21. 23. Our life
  22. 24. Genes <ul><li>Each of these beads is called a gene </li></ul><ul><li>Each gene is a piece of genetic information </li></ul><ul><li>Thousands of genes make up each chromosome </li></ul><ul><li>Since the chromosomes come in pairs, there are two copies of the genes. </li></ul><ul><li>The exception to this rule applies to the genes carried on the sex chromosomes: the X and Y. </li></ul><ul><li>Since men have only one copy of the X chromosome, they have only one copy of all the genes carried on the X chromosome </li></ul>
  23. 25. Human Genome <ul><li>The human genome is a complete copy of the entire set of human gene instructions.  </li></ul><ul><li>The Human Genome Project , completed in 2003, identified all the human genes in DNA and stored the information in databases so all researchers everywhere could use it. </li></ul>
  24. 26. Number of Genes <ul><li>Our genes have an important role in our cells </li></ul><ul><li>Each gene has its own specific location on the chromosome and is a piece of the genetic material that does one particular job. </li></ul><ul><li>A gene is a distinct portion of a cell’s DNA. Genes are coded instructions for making everything the body needs, especially proteins. Human beings have about 25,000 genes. • </li></ul><ul><li>The DNA code is made up of very long chains of four chemical ‘letters’: A denine (A), G uanine (G), T hymine (T) and </li></ul><ul><li>C ytosine (C) </li></ul><ul><li>– In the DNA information, each ‘word’ is a combination of three of these four chemical ‘letters’ A, G, C and T </li></ul><ul><li>– Each three-letter word ( triplet ) tells the cell to produce a particular amino acid that form proteins </li></ul>
  25. 27. Chromosomes & genes
  26. 28. Gene <ul><li>A gene is a distinct portion of a cell’s DNA. Genes are coded instructions for making everything the body needs, especially proteins. Human beings have about 25,000 genes. </li></ul><ul><li>Our genes also contain the information for how we look: the colour of our eyes, how tall we are, the shape of our nose, etc. </li></ul><ul><li>The information is in the form of a chemical (DNA) code (the genetic code </li></ul>
  27. 29. Gene <ul><li>Our genes have an important role in our cells </li></ul><ul><li>Each gene has its own specific location on the chromosome and is a piece of the genetic material that does one particular job </li></ul>
  28. 30. DNA- Information <ul><li>The DNA code is made up of very long chains of four chemical ‘letters’: A denine (A), G uanine (G), T hymine (T) and C ytosine (C) – In the DNA information, each ‘word’ is a combination of three of these four chemical ‘letters’ A, G, C and T </li></ul><ul><li>– Each three-letter word ( triplet ) tells the cell to produce a particular amino acid that form proteins – The sequence of three-letter words in the gene enables the cells to assemble the amino acids in the correct order to make up a protein </li></ul>
  29. 31. DNA <ul><li>– </li></ul><ul><li>Different genes are active in different cell types, tissues and organs, producing the necessary specific proteins; some genes are ‘switched off’ and others are ‘switched on Changes to the genetic code can mean that a particular protein is not produced properly, produced in the wrong amounts or not produced at all </li></ul><ul><li>In some cases, the change in the genetic code can result in a genetic condition, affecting our growth, development and how our bodies work </li></ul>
  30. 32. Human chromosomes
  31. 33. Human Chrosomes - crossing over
  32. 34. Human XY chromosomes
  33. 35. Human sex chromosomes <ul><li>XX & XY </li></ul>
  34. 36. Human sex chromosoms
  35. 37. XY
  36. 38. Mutation <ul><li>The particular order of the pairs of As, Ts, Cs, and Gs is extremely important in the DNA. Sometimes there is a mistake — one of the pairs gets switched, dropped, or repeated. This changes the coding for one or more genes. This is called genetic mutation. A mutation maybe disease-causing or harmless. </li></ul>
  37. 39. Y Chromosomes evolution in Animals
  38. 40. Y is declining
  39. 41. Degeneration of Y <ul><li>Both sex chromosomes have the same origin evolutionary mechanisms which allowed the Y chromosome to shrink – that is still debatable. </li></ul><ul><li>Simulations have shown that the strategy of sexual reproduction (more explicitly the promiscuity of women) is responsible for shrinking of Y chromosome, </li></ul><ul><li>, when woman (XX) can freely choose a man (XY) as a partner for reproduction from the whole population of males, the Y chromosome accumulates defects and eventually the only information it brings is a male sex determination </li></ul>
  40. 42. Dunnart – marsupial..4 genes
  41. 43. Degeneration of Y-why? <ul><li>when woman (XX) can freely choose a man (XY) as a partner for reproduction from the whole population of males, the Y chromosome accumulates defects and eventually the only information it brings is a male sex determination The fraction of males is less important or even unimportant, because after conception the male partners are returning to the pool. Thus, one male can be a father of many offspring of different females. As a result of shrinking Y chromosome, the males become hemizygous in respect to the X chromosome content (have only one copy – half of information possessed by females in the X chromosome) and are characterized by higher mortality, observed in the human populations. If it is assumed in the model that the </li></ul>.
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