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Multiple alleles for the ABO blood groups

A and B are codominant , O is recessive to A and B. Multiple alleles for the ABO blood groups. PLEIOTROPY One gene (or genotype) results in multiple phenotypes. Many different outward effects on the organism. Pleiotropic effects of the sickle-cell allele in a homozygote.

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Multiple alleles for the ABO blood groups

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  1. A and B are codominant, O is recessive to A and B Multiple alleles for the ABO blood groups

  2. PLEIOTROPY One gene (or genotype) results in multiple phenotypes. Many different outward effects on the organism.

  3. Pleiotropic effects of the sickle-cell allele in a homozygote

  4. POLYGENIC INHERITANCE -Multiple genes resulting in one phenotype. Ex. Skin color, eye color.

  5. At least 2 genes invloved in pigment formation. (Location of color also important)

  6. A simplified model for polygenic inheritance of skin color Environmental effects also affect the range of phenotype (multifactorial trait)

  7. The effect of environment of phenotype Soil acidity effects the color of hydrangeas. Temperature sensitive mutations for pigment formation

  8. HEREDITY What is it that allows life to continue from generation to generation? What is it that is passed on? What is the common thread that connects all life?

  9. Late 1850’s - Principles of inheritance Concept of “genes”, discrete units of inheritance that determine specific traits. Genes segregate and re-assort. Microscopy showed “chromosomes” segregating during cell division.

  10. WHAT IS THE GENETIC MATERIAL? PROTEIN OR DNA? Chromosomes are composed of both DNA and Protein.

  11. Nucleic Acids The subunits of nucleic acids are nucleotides. The two types of nucleic acids are RNA and DNA.

  12. Figure 16.2a The Hershey-Chase experiment: phages

  13. Figure 16.2b The Hershey-Chase experiment

  14. THE RACE IS ON TO DETERMINE THE MOLECULAR STRUCTURE OF DNA! Linus Pauling Wilkins and Franklin Watson and Crick

  15. Chemical composition of DNA

  16. Base pairing in DNA Chargaff’s Rules: G = C, A = T

  17. Figure 16.4 Rosalind Franklin and her X-ray diffraction photo of DNA

  18. Figure 16.0 Watson and Crick

  19. Figure 16.5 The double helix Strands “anti-parallel” 5’ end 3’ end 3’ end 5’ end

  20. J.D. Watson, F.H.Crick, “Molecular Structure of Nucleic Acids: A Structure for Deoxyribonucleic Acids.” Nature 171 (1953): 738 “It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.”

  21. “Semi-Conservative Replication”

  22. Origins of replication in eukaryotes

  23. Incorporation of a nucleotide into a DNA strand Anti-parallel DNA strands 5’ 3’ 3’ 5’

  24. DNA REPLICATION Helicase separates strands and unwinds DNA DNA polymerase reads “template” and incorporates proper nucleotide. DNA Ligase seals newly made fragments.

  25. DNA polymerase incredible fast and accurate! 50-500 nt/second! Error rate 1/10,000 DNA Polymerase “Proofreading” Excision/Repair enzymes

  26. Nucleotide excision repair of DNA damage (Caused by U.V. irradiation)

  27. Mutations which affect DNA replication and DNA repair have been associated with some cancers and in premature aging diseases. Xeroderma Pigmentosum

  28. HOW IS THE INFORMATION STORED IN THE DNA UTILIZED? DNA RNA PROTEIN WHAT IS THE GENETIC CODE? Transcription Translation

  29. The triplet code

  30. By the mid-1960s the entire code was deciphered. • 61 of 64 triplets code for amino acids. • The codon AUG not only codes for the amino acid methionine but also indicates the start of translation. • Three codons do not indicate amino acids but signal the termination of translation.

  31. The Process of Transcription Production of an RNA copy (transcript) of a gene. 3 main types of RNAs (both proks. and euks.) - mRNA (messenger RNA) - rRNA (ribosomal RNA) - tRNA (transfer RNA) How are these RNAs made? What are their functions in the cell?

  32. Transcriptioncan beseparatedinto threestages:initiation, elongation, andtermination.

  33. As RNA polymerase moves along the DNA, it untwists the double helix, 10 to 20 bases at time. • The enzyme addsnucleotides to the3’ end of thegrowing strand. • Behind the pointof RNA synthesis,the double helixre-forms and theRNA moleculepeels away.

  34. Exon Intron Exon Intron Exon DNA Transcription Addition of cap and tail Cap RNA transcript with cap and tail Introns removed Tail Exons spliced together mRNA Coding sequence Nucleus Cytoplasm Figure 10.10

  35. 1. Messenger RNA Structure and Function The Genetic Code is a triplet code. 3 nucleotides = 1 amino acid 4x4x4 = 64 3 nucleotide “codons”, more than enough to code for the 20 different amino acids found in proteins.

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