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Unit VII: Genetics

Explore Gregor Mendel's pea plant experiments, the concept of true breeding, gene segregation, Punnett squares, probabilities in inheritance, and other patterns in genetics.

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Unit VII: Genetics

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  1. Unit VII: Genetics Understanding our genes and the ways they are passed to the next generation. Modern Genetics Basic Genetics

  2. A. Basic Genetics Genetics = study of heredity understanding of how characteristics get passed from parent to offspring, generation to generation 1. Gregor Mendel Monk - studied pea plants in the 1800’s a) True breeding = purebred b) Traits = specific characteristic Seed Shape – ________________ Seed Color – _________________ Seed Coat – __________________ Pod Shape – _________________ Pod Color – __________________ Flower Position – ______________ Flower Color – ________________ Plant Height – ________________ Trait Allele = ________________

  3. c) Generations P = parent generation – original plants F1 = first filial generation = offspring of the original plants F2 = second filial generation = offspring of F1 d) ___________ – for each trait Mendel crosses true breeding plants and makes observations of the offspring ex: P  ____________________________ F1 ________________________ All tall plants Only 1 characteristic showed in the F1 generation Why not a blend of the parent plants? _________ – ____________________________ ______________________________

  4. e) Conclusions 1. biological inheritance is determined by factors that are passed from one generation to the next ________________ ________________________ 2. ____________________ – _______ _______________________________________________________________________________________________________________________________.

  5. f) Segregation What about the F2 generation? What happens next? Were the recessive alleles still present in the pea plant? Cross - ________________ Ex: ________________________________________

  6. F2 – Mostly Tall; some Short; Short trait reappeared Some how the short trait separated from the tall trait

  7. 1. ________________________________________ ___________________________________________________________________________________________________________________________________. As a result of fertilization, _________________________. As a consequence, _____________________ are likely to be produced. Short separated from tall

  8. 2. Probability and Inheritance a) ________ = ____________________________________ _____________ = same alleles (TT or tt) _____________ = different alleles (Tt) = Hybrid b) ___________ = ____________________ (Tall or Short) Usually determined by the genotype – _____________ ____________________________________________. Can two organisms have the same phenotype but different genotypes? Phenotype = Tall ____________________ How could the genotype be determined? _______________________________________

  9. c) Punnett Square representation of parental gametes and the different allelic combinations of the offspring ex: Cross: True breeding Tall x True breeding Short 1. Determine the genotypes of the parents 2. Determines the possible gametes of the parents (segregation) 3. Write the gametes on the outside of the box 4. Combine the parents gametes (recombination) Remember only 1 gamete from each parents ______________________________________________________________________________________________________________________________

  10. What is the genotype ratio? What is the phenotype ratio? ex: Cross: Heterozygous Tall x Heterozygous Tall Through his knowledge of math and detailed record keeping, with thousands of pea plants Mendel always had this ratio in the phenotypes.

  11. d) _____________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________. What if the plants are tall with round seeds and short with wrinkled seeds what allelic combinations will occur in successive generations? Not only did Mendel look at single traits, he observed the probability of the inheritance of multiple traits at the same time. What if the genes are on the same chromosome? - _________________

  12. the organisms are heterozygous for two traits. (Use letters that are easy to tell the difference) ex: Dihybrid Cross Phenotype Ratio: ______________ ______________ ______________ ______________

  13. 3. Other Patterns of Inheritance Not all genes come with dominant and recessive alleles a) _____________________ – neither allele is dominant ___________________________________________ ex: Flower Color in Snap Dragons R = red; W = white Red Flower x White Flower Genotype Ratio: Phenotype Ratio:

  14. b) Codominance ________________________________ some cells produce one allele other cells produce the other ex: Roan Colored Cattle R = red coat; W = white coat RW = Roan = Some red hair some white hair in the coat What is the probability that the offspring of two roan colored cattle would be roan colored?

  15. c) Multiple Alleles genes that have __________________________ the individual only has 2 alleles, but more than two exist in the population ex: Blood Types _________________________________ _________________________________________________ Who is the Daddy? A woman with type A blood has a child with type O blood, but she is unsure of the father. Bob has type AB blood and Bill has type A blood. Who is the baby’s daddy?

  16. d) Polygenic Traits traits produced by the interaction of many genes Show a wide range of phenotypes Ex: Skin color, Eye Color, Height

  17. e) Sex Linked Traits genes that occur on the sex chromosomes X and Y chromosomes  XX = female; XY = male X chromosome is larger and carries more genes Since males only have 1 X chromosome, what ever allele is on the chromosome shows up in the phenotype Females have two alleles for the gene ex: color blindness and hemophilia eye color in drosophila

  18. Ex: Color Blindness A normal man and a woman that is a carrier for colorblindness have children. a) What is the chance they will have a colorblind child? b) If they are having a girl what is the chance she will be colorblind? A boy?

  19. 4. Human Inheritance a) Pedigree a diagram of family relationships that uses symbols to represent people and lines to represent genetic relationships. easier to visualize relationships within families Pedigrees are often used to determine the mode of inheritance (dominant, recessive, etc.) of genetic diseases.

  20. b) Karyotype and Amniocentesis picture of chromosomes 22 pairs of autosomes, 1 pair of sex chromosomes Used to determine gender and chromosomal disorders

  21. c) Human Genetic Diseases / Disorders 1) Albinism _________________ lack pigment in skin, hair, eyes 2) Cystic Fibrosis _________________ excess mucus in lungs; increases susceptibility to infections; death in childhood unless treated

  22. 3) Phenylketonuria (PKU) _________________ accumulation of phenylalanine (amino acid) in tissue body can not break down the amino acid mental retardation if they eat phenylalanine 4) Tay-Sachs Disease ____________________ higher occurrence (1/100 vs 1/100,000) in Jewish families of eastern European ancestry lipid accumulation in brain cells, nervous system break down  death in early childhood

  23. 5) Achondroplasia Dwarfism dominant allele bones fuse and stop growth 6) Sickle Cell Anemia ____________________ red blood cells have a crescent shape misshapen hemoglobin can not carry O2 as well

  24. 7) Polydactyl dominant allele extra toes and fingers not always expressed 8) Down Syndrome chromosomal disorder extra 21st chromosome cause by _____________________

  25. 9) Huntington’s Disease ______________________ Usually ___________ of symptoms ______________, loss of coordination 10) Duchenne muscular dystrophy ___________________ Muscle degeneration that causes usually death

  26. B. Modern Genetics 1. Griffiths’ Experiments – 1920s 2 Strains of bacteria One strain is deadly Even when killed, the deadly strain can pass something to the non-deadly strain to make it a killer!

  27. 2. Avery’s Experiments – 1940s Repeats Griffith’s experiments but adds enzymes that break down different compounds in the cells Not until he destroys DNA that the mice live!

  28. 3. Watson and Crick – 1950’s Used Rosalind Franklin’s x-ray pattern of DNA to build its 3-D structure _____________________________ _____________________________ a) DNA Structure Nucleotides A = _________________ B = _________________ C = _________________ Nucleotide  Gene  Chromosome ______________________________________________ ________________________________________________ From the human to the DNA – PBS Flash

  29. DNA STRUCTURE MOVIE

  30. 4. DNA Replication a) Occurs inside _________  during S phase of cell cycle b) DNA molecules ____________________, then produces two _______________________ following the rules of base pairing c) Each original strand serves as ______________ the new strand

  31. Original DNA DNA “Unzips” Enzymes fill in nucleotides A T G G C C T G G G C A T C C G T T A T C A T G G C C T G G G C A T C C G T T A T C T A C C G G A C C C G T A G G C A A T A G T A C C G G A C C C G T A G G C A A T A G

  32. Easy Version of DNA Replication Check out this site on your own for a more detailed explantation More Complicated but explains the process really well. http://207.207.4.198/pub/flash/24/menu.swf

  33. 5. Protein Synthesis a) RNA = ____________________ single stranded nucleic acid contains Ribose as the sugar not __________ as in DNA has the base Uracil instead of _________ as in DNA Types of RNA

  34. b) Transcription 1st step of protein synthesis; similar to replication DNA  mRNA Occurs in the ______________ “Unzip” DNA – uses ______________________________ RNA polymerase fills in complimentary RNA bases mRNA detaches from DNA mRNA leaves nucleus Simple Trasncription Animation Just another Trancription animation

  35. Original DNA DNA “Unzips” Enzymes fill in RNA nucleotides RNA breaks from DNA DNA reconnects T A C C G G A C C C G T A G G C A A T A G A T G G C C T G G G C A T C C G T T A T C A U G G C C U G G G C A U C C G U U A U C The groups of 3 bases on the mRNA is called a CODON The codon codes for specific amino acids when making a protein

  36. c) Translation 2nd step of protein synthesis ______  ______  _____  ______ occurs in the ______________ at the _______________ Ribosome reads __________ on mRNA Matches the _______ to an ____________ on tRNA Ribosome reads next codon and brings in next tRNA with matching anticodon Since tRNA is attached to Amino Acids – __________ ______________________ _____________ This proximity allows the _______________ Makes a peptide Repeats until mRNA says stop

  37. More than 1 ribosome can attach to the mRNA at a time Makes multiple peptides Translation Animation

  38. To see it in some more detail check out the following website on protein synthesis http://learn.genetics.utah.edu/content/begin/dna/ d) Protein Synthesis Overview e) Genes code for peptides generally a protein is the combination of more than 1 peptide Try this website as an interactive for replication and protein synthesis http://www.pbs.org/wgbh/aso/tryit/dna/shockwave.html

  39. 6. Mutations Changes in the DNA sequence Some are good Some are bad Most are neutral Mutations are only passed to the next generation if they occur in gametes Mutations in somatic cells are not passed – acquired characteristics are not passed

  40. a) Gene Mutations changes in a single gene 1) Point Mutations – involve just one nucleotide ______________ = change one nucleotide for another ex: T A C G C G A C C C G A becomes T A C G C C A C C C G A the change may or may not change the amino acid

  41. 2) ________________________ _________________________ of a single nucleotide changes _____________________________________ usually affects all amino acids after the mutation ex: DNA: T A C C G G A C C C G A mRNA: A U G G C C U G G G C U Amino A: Met Ala Try Cys Insertion DNA: T A C GC G G A C C C G A mRNA: A U G C G C C U G G G C U Amino A: Met Arg Leu Gly The order of amino acids changed  changes protein (big time)

  42. Ex: delete 1 letter THE FAT CAT ATE THE RAT  THE FTC ATA TET HER AT ???? Completely change everything after the deletion No longer makes sense The same thing happens with the protein The order of the letter (amino acids) determines the structure of the words and sentence (protein) One little mistake can completely change the meaning

  43. b) Chromosomal Mutations changes the structure of a chromosome rearrange the genes on a chromosome 1) _________________ 2) _________________ 3) _______________________________ 4) _______________________________ ______________________________________ Chromosomal Mutations

  44. c) Mutagenic Agents factors that cause mutations 1) Radiation – X-rays ultraviolet radioactive substances, and cosmic rays 2) Chemicals – formaldehyde, benzene, asbestos fibers THC nicotine

  45. 7. DNA Technology ways in which the knowledge of DNA can help benefit society a) Selective Breeding _______________________________________________ _________________________________________________ _______________ ex: dogs, cattle, crops selective breeding has been occurring for 1000s of years

  46. b) Genetic Engineering recombinant DNA; transfer DNA from one organism to another isolate gene  ________________________________  combine DNA of organisms  place recombinant DNA in a new organism *restriction enzymes = cut DNA at very specific sequences

  47. can be used to make a variety of products bacteria that can make: Insulin, Human Growth Hormone crops that resistant to disease and insects livestock with extra copies of growth hormone gene

  48. c) Cloning making an exact genetic copy Remove the nucleus of an egg cell Use the nucleus of a body cell  Insert the nucleus into the egg cell  Grow the egg cell  Identical genetic copy of the body cell organism Click and Clone

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