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DNA, Proteins, and Ways We Are Different

DNA, Proteins, and Ways We Are Different. Biological Anthropology. Remember these guys?. A chromosome contains genes. DNA. Sugar-phosphate backbone” Bases are “rungs” adenine = thymine cytosine = guanine. Protein Synthesis. A two stage process Transcription Translation Our players:

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DNA, Proteins, and Ways We Are Different

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  1. DNA, Proteins, and Ways We Are Different Biological Anthropology

  2. Remember these guys?

  3. A chromosome contains genes

  4. DNA • Sugar-phosphate backbone” • Bases are “rungs” adenine = thymine cytosine = guanine

  5. Protein Synthesis • A two stage process • Transcription • Translation • Our players: • Messenger RNA (mRNA) – the locks • Transfer RNA (tRNA) – the keys • Ribosome (“locksmith) • Amino Acids

  6. Protein Synthesis 1: Transcription • messenger RNA (mRNA) copy of gene is made • mRNA copy leaves nucleus and goes to cytoplasm

  7. Protein Synthesis 2: Translation • mRNA copy is “read” by ribosomes • Ribosomes match tRNA to codons on mRNA

  8. Proteins: the End Result • One gene codes for one protein • Differences between individuals due (in part) to differences in their proteins

  9. Evolution defined drum roll please… A change in allele frequency from one generation to another

  10. Some Examples of Variation in Our Blood Cells

  11. Let’s Start with the Outside…

  12. Genotype AA, AO BB, BO OO AB Phenotype A B O AB ABO Blood Group Alleles A B O codominant recessive

  13. ABO Differences

  14. Genotype DD, Dd dd Phenotype Rh+ Rh- Rh (Rhesus) Blood Group Alleles D d dominant recessive

  15. Maternal/Infant Rh Incompatibility

  16. Let’s Go Inside…

  17. The Classic Example Red-Blood Cell Sickling and Malaria

  18. Red Blood Cells App. 30 trillion RBC in the human body you are both destroying (and making) new red blood cells at a rate of around 2.7 million cells per second. Every red blood cell contains about 270 million hemoglobin molecules, each one capable of carrying four oxygen molecules

  19. Beta Hemoglobin • Protein consists of 146 amino acids • Gene consists of 438 bases (146 X 3) • Protein comes in two forms

  20. Two Forms of Beta Hemoglobin • Normal Hemoglobin (A) • Mutated Hemoglobin (S)

  21. The “Normal” Situation(HbA allele) DNA: GGA CTC CTC TTT Codon #5 #6 #7 #8 Amino Acid #6 Glutamic Acid

  22. The “Mutated” Situation(HbS allele) DNA: GGA CAC CTC TTT Codon #5 #6 #7 #8 Amino Acid #6 Valine

  23. The Difference is in Codon #6 Normal allele: CTC Normal A.A.: Glutamic Acid Mutated allele: CAC Substituted A.A.: Valine Everything else is the same: 145 identical amino acids 437 identical DNA bases

  24. Genotype HbA HbA HbA HbS HbS HbS Phenotype Sickle-Cell Alleles HbA HbS normal codominant sickle-cell trait codominant sickle-cell anemia

  25. Red Blood Cells ‘donut’ shaped sickle shaped

  26. A simple mutation with multiple effects

  27. Sickle-Cell in the U.S. • Sickle cell anemia is the most common inherited blood disorder in the US • More than 70,000 people have sickle cell disease • Sickle cell disease occurs in 1 in every 500 African Americans • About 8% of African Americans are carriers of sickle cell disease • Two million people have sickle cell trait • Approximately 1 in 12 African Americans has sickle cell trait

  28. Heterozygote Advantage

  29. What possible advantagecould sickle-cell offer?

  30. Malaria • Infectious disease caused by • Falciparum plasmodium • Mosquito is carrier

  31. Malaria • perhaps the most deadly organism in the world (to humans) • 300-500 million people in the world • 1-1.5 million people die each year

  32. Malaria • Parasite infects blood • Part of life cycle occurs in red blood cells • Population continuously infected

  33. Distribution of Malaria

  34. Distribution of the HbS allele

  35. The Connection • Heterozygote has greatest fitness in malarial environment • Both high in frequency

  36. ABO Differences

  37. Viruses • Not alive • Require host cell to reproduce • Symptoms and effects relate to which host cells are used

  38. Viruses • Viruses use the cells genetic machinery to make new copies

  39. Influenza A Virus Highly variable surface structures Mutates readily Avoidance behaviors frequent handwashing covering coughs having ill persons stay home, (except to seek medical care) minimize contact with others in the household who may be ill with swine-origin influenza virus. Model of the influenza A virus showing HA and NA receptors projecting from the surface of the virus.Source: http://www.udel.edu/chem/white/C647/FluVirus.GIF; accessed May 5, 2009.

  40. H1N1 Virus

  41. H1N1 Virus A “triple reassortment” virus consisting of human, avian, and swine influenzas Virus strains 90% identical to H1N1 have been circulating in swine for approximately 10 years Combination of viral strains thought to have arisen when live pigs were transported between North America and Eurasia Source: http://www.gate2biotech.com/origins-of-the-swine-flu-virus/; accessed on 24 Nov. 2009

  42. HIV Virus • The hosts of HIV areCD4 (aka T4 or T-helper) cells • These cells are part of the body’s immune system • Infection can lead to AIDS

  43. From HIV to AIDS • HIV+ • exposure to virus and antibody production • CD4 (t-cell) count drops after infection, rebounds, then diminishes • ≤ 200 = “AIDS” • Acquired ImmuneDeficiency Syndrome

  44. Mechanism by which HIV attaches to and is absorbed into a CD4+ cell Source: US National Institutes of Health - National Institute of Allergy and Infectious Diseases [Public domain], https://commons.wikimedia.org/wiki/File%3AHIV_attachment.gif ; downloaded 24 Nov. 2015

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