The Human Genome<br />From Peas and fruit flies to humans…<br />
What is a genome???<br />All the genetic information (genes) that make up an organism<br />
What makes us human?<br />Analyze human chromosome…<br />Karotype<br />Picture of all the chromosomes in an organism<br />...
Pedigree Charts<br />Shows relationships within a family<br />Genetic counselors use these to infer the genotypes of famil...
Disorders can be recessive or dominant<br />
Recessive disorders<br />Disorder phenylketonuria (PKU)<br />Caused by an autosomal recessive allele on chromosome 12<br /...
Autosomal Recessive Allele<br />Tay-Sachs Disease<br />Recessive allele in Jewish families of central and eastern Europe a...
Autosomal Recessive Disorders<br />Cystic Fibrosis<br />Do not have the gene that regulates mucus production<br />Excess m...
Autosomal Dominant Disorders<br />You will express disorder if you are homozygous or heterozygous dominant for that trait<...
Co-Dominant Alleles Disorders<br />Sickle cell anemia<br />1/500 African Americans have the disorder<br />Co-dominant alle...
Sex-Linked Disorders<br />Many sex-linked genes are found on x-chromosome<br />Many genetic disorders are sex-linked<br />...
Sex-linked Disorders<br />Red-green Color-blindness <br />1/10 men<br />1/100 women<br />Hemophilia<br />Two important gen...
X-chromosome Inactivation<br />Females have XX and males have XY…is the second X chr in females needed??<br />British Gene...
Barr bodies in cats<br />Gene that controls color of coat spots is located on the X-chrm<br />In a female, one X-chrm may ...
Chromosomal Disorders<br />Mechanics of meiosis (where we separate chromosomes) is usually pretty good<br />But nobody’s p...
Nondisjunction<br />If one of the gametes with an ABNORMAL # ends up getting fertilized, MAJOR problems!!!<br />Trisomy: “...
Down Syndrome<br />Extra copy of chromosome 21<br />1/800 baby’s are born with this disorder<br />Produces mild to severe ...
Sex Chromosome Disorders<br />What happens if nondisjunction happens to the  sex chromosomes???<br />We know we need at le...
Turner’s Syndrome<br />
What about an extra Y?<br />Males with 47, XYY produce more male hormones and express a more expressive behavior<br />More...
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Human genetics

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Human genetics

  1. 1. The Human Genome<br />From Peas and fruit flies to humans…<br />
  2. 2.
  3. 3. What is a genome???<br />All the genetic information (genes) that make up an organism<br />
  4. 4. What makes us human?<br />Analyze human chromosome…<br />Karotype<br />Picture of all the chromosomes in an organism<br />Autosomes<br />CHROMOSOMES 1-44 (pairs 1-22)<br />Autosomal chromsomes<br />Sex chromosomes<br />Determine a person’s sex (male XY or female XX)<br />Chromosome 45 and 46 (set 23)<br />
  5. 5.
  6. 6. Pedigree Charts<br />Shows relationships within a family<br />Genetic counselors use these to infer the genotypes of family members<br />Look at each generation different symbols used<br />
  7. 7.
  8. 8. Disorders can be recessive or dominant<br />
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  10. 10. Recessive disorders<br />Disorder phenylketonuria (PKU)<br />Caused by an autosomal recessive allele on chromosome 12<br />People with this disorder lack the enzyme to break down phenylalanine (amino acid found in milk and many other foods)<br />In newborns, this causes a build up of phenylalanine in tissues during the first few years of life and lead to mental retardation<br />Newborns are commonly tested for PKU and then put on a low phenylalanine diet if they have the disorder<br />
  11. 11. Autosomal Recessive Allele<br />Tay-Sachs Disease<br />Recessive allele in Jewish families of central and eastern Europe ancestry<br />Lack the enzyme to break down lipids in neural cells<br />Lipid accumulation in brain cells<br />Leads to nervous system break-down and death in the first few years of life<br />
  12. 12. Autosomal Recessive Disorders<br />Cystic Fibrosis<br />Do not have the gene that regulates mucus production<br />Excess mucus in lungs, digestive tract, and liver<br />Increased susceptibility to disorders<br />Lung transplants usually needed after childhood<br />
  13. 13. Autosomal Dominant Disorders<br />You will express disorder if you are homozygous or heterozygous dominant for that trait<br />You also have higher chances of passing onto your children<br />Dwarfism (achondroplasia)<br />Huntington’s Disease<br />Nervous system disorder<br />
  14. 14. Co-Dominant Alleles Disorders<br />Sickle cell anemia<br />1/500 African Americans have the disorder<br />Co-dominant allele<br />Causes blockages in blood vessels, preventing oxygen from getting to other cells and tissues<br />Beneficial in central and east Africa because it helped destroy malaria<br />If you had SCA, your body would destroy the sickle cells to protect itself and in the process, destroy the malaria parasite as well<br />
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  16. 16. Sex-Linked Disorders<br />Many sex-linked genes are found on x-chromosome<br />Many genetic disorders are sex-linked<br />Males have just ONE x chromosome, so whatever the X chromosome is carrying (dominant or recessive) will be expressed<br />Fathers can pass it to their daughters and the disorder can show up in the daughters sons<br />
  17. 17. Sex-linked Disorders<br />Red-green Color-blindness <br />1/10 men<br />1/100 women<br />Hemophilia<br />Two important genes on x-chr control blood clotting<br />Person with disorder can die from minor cuts <br />Recessive allele in either gene can cause it<br />Duchenne Muscular Dystrophy<br />Caused by defective version of a gene for a muscle protein<br />Progressive weakening and loss of skeletal muscle1/3000 males<br />
  18. 18. X-chromosome Inactivation<br />Females have XX and males have XY…is the second X chr in females needed??<br />British Geneticist Mary Lyon <br />In female cells, one x-chromosome is randomly shut off…this “shut off” chromosome is called a Barr Body<br />Different X-chrm are switched off in different cells<br />Generally not found in males b/c X-chrm needs to be ACTIVE<br />Occurs in other mammals as well<br />
  19. 19. Barr bodies in cats<br />Gene that controls color of coat spots is located on the X-chrm<br />In a female, one X-chrm may have the allele for orange spots and the other X-chrm may have the allele for black spots<br />Different cells in different parts of the cat’s body are switched off= different colored spots on different parts of the cat…mix or orange and black spots<br />Males only have ONE active X-chrm…therefore, will they have different colored spots?<br />No…only psots of ONE color (b/c on ONE active X)<br />This is one way to determine the sex of a cat…cat with black AND orange spots is almost always certainly female<br />
  20. 20.
  21. 21. Chromosomal Disorders<br />Mechanics of meiosis (where we separate chromosomes) is usually pretty good<br />But nobody’s perfect…mistakes happen….<br />Most common problem…<br />Nondisjunction: when homologous chromosomes fail to separate properly<br />Literally means “not coming apart”<br />If this occurs, ABNORMAL #s of chromosomes may find their way into gametes and a disorder of chromosome number may result<br />
  22. 22. Nondisjunction<br />If one of the gametes with an ABNORMAL # ends up getting fertilized, MAJOR problems!!!<br />Trisomy: “three bodies”<br />Occurs when an autosomal chromosome fails to separate during meiosis<br />When do chrm separate?<br />Anaphase I and Anaphase 2<br />One gamete ends up with an extra copy of a chromosome and then the fertilized zygote ends up with 3 copies of a chrm instead of 2<br />Example: Downs Syndrome<br />
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  25. 25. Down Syndrome<br />Extra copy of chromosome 21<br />1/800 baby’s are born with this disorder<br />Produces mild to severe retardation<br />Increased susceptibility to diseases, slower development, and higher frequency of birth defects<br />How can one little extra copy cause so many problems?<br />Scientists are still trying to figure that out…now that they have used gene mapping and identified all the genes on chromosome 21, they can begin experimenting on this problem<br />
  26. 26. Sex Chromosome Disorders<br />What happens if nondisjunction happens to the sex chromosomes???<br />We know we need at least one X chromosome….<br />No embryos have been found with just a Y chromosome so we now X chrm contains vital genes!<br />Turners Syndrome<br />Females receive only one X chromosome<br />Karotype 45, X<br />Unable to reproduce, sex organs do not develop at puberty<br />Klinefelters Syndrome<br />Males receive an extra X chromosome<br />Karotype 47, XXY<br />Prevents individuals from reproducing<br />Cases of individuals with XXXY and XXXXY<br />Y chromosome contains “sex determining region” SDR, which gives male characteristics and development<br />If region is absent, embryo develops into female<br />
  27. 27. Turner’s Syndrome<br />
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  29. 29. What about an extra Y?<br />Males with 47, XYY produce more male hormones and express a more expressive behavior<br />More testosterone=more aggressive behavior<br />Higher number of men in prison for violent crimes have XYY however there is a large population of men with XYY that do not exhibit (or at least act upon) this aggression<br />Cannot use this as an excuse for aggressive behavior or else criminals would be pleading an extra Y instead of insanity :-o<br />

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