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Goal 3 Genetics

Goal 3 Genetics. Cell Cycle. Cell Cycle. Interphase = majority of the life of a cell–the time during which it grows and prepares for replication Mitotic Phase- Mitosis and Cytokinesis. Mitosis. Mitosis = division of the nucleus Four phases:

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Goal 3 Genetics

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  1. Goal 3 Genetics

  2. Cell Cycle

  3. Cell Cycle • Interphase= majority of the life of a cell–the time during which it grows and prepares for replication • Mitotic Phase- Mitosis and Cytokinesis

  4. Mitosis • Mitosis= division of the nucleus • Four phases: • Prophase– chromatin condenses to show individual chromosomes; centrioles replicate and spindle begins to form; nucleus dissolves • Metaphase– chromosomes line up along the center of the cell; each chromosome is attached to spindle fiber at centromere • Anaphase– sister chromatids separate into opposite sides of the cell • Telophase– chromatids gather at opposite ends of cell; nuclei reform; spindle disappears

  5. Mitosis • Two IDENTICAL cells are formed (diploid) • Asexual reproduction • Occurs in somatic cells (body cells)

  6. Mitosis

  7. Cytokinesis • Cytokinesis– division of the cytoplasm – occurs directly after telophase of mitosis and telophase I and II of meiosis

  8. Meiosis • Two divisions with 4 phases in each: • Meiosis I • During prophase I, crossing over occurs between homologous chromosomes • During metaphase I, homologous chromosomes line up at center of cell • During anaphase I and telophase I, homologous chromosomes are separated into different sides of the cell • Meiosis II • Looks much like mitosis in that sister chromatids are separated

  9. Meiosis • Four DIFFERENT cells are formed • Genetic variation!!!!!! • Sexual reproduction • Occurs in sex cells (gametes = sperm and egg) • Daughter cells have ½ the number of chromosomes that the parent cell had (haploid)

  10. Mendelian Genetics • Gregor Mendel was a monk that studied cross-pollination in pea plants and recognized predictable patterns of inheritance. • Probability and Punnett Squares • Vocabulary to KNOW:

  11. Mendelian Genetics • trait—a characteristic • allele—different forms of a gene • dominant—allele that is always expressed, capital letter • recessive—weaker allele, only expressed if dominant is not present, lower-case letter • homozygous—2 of the same alleles, TT or tt • heterozygous—2 different alleles, Tt • genotype—the genetic makeup, the letters of the alleles • phenotype—the physical characteristic the letters stand for

  12. Non-Mendelian Genetics • Codominance – two alleles are equally dominant, therefore the heterozygote shows bothalleles. • Example: In cows, Black (BB) and White (WW) are codominant; BW is spotted. • Problem: If a Black Cow and a Spotted Bull are mated, what is the probability of a spotted baby?

  13. Non-Mendelian Genetics • Problem: If a Black Cow and a Spotted Bull are mated, what is the probability of a spotted baby? BB = black (2) BW= spotted (2) 50% spotted or 1/2 B B B BB BB W BW BW

  14. Non-Mendelian Genetics • Incomplete Dominance– one allele is not completely dominant over another, therefore the heterozygote is a blend of the two alleles. • Example: In snapdragons, Red (RR) and White (WW) are incompletely dominant. RW is a pink flower. • Problem: If two pink flowers are crossed, what is the probability of a red flower?

  15. Non-Mendelian Genetics • Problem: If two pink flowers are crossed, what is the probability of a red flower? R W RR = red (1) RW= pink (2) WW= white (1) ¼ or 25% red RR RW R RW WW W

  16. Non-Mendelian Genetics • Multiple Alleles : there are more than 2 alleles for a trait • Example: Human Blood types. Type A and Type B are codominantover Type O. • There are 4 possible blood types and 6 possible genotypes: ** IAIA and IBIB are homozygous **IAi and IBi are heterozygous

  17. Non-Mendelian Genetics Problem: Bob has type AB blood and his wife, Annie, is heterozygous for type A blood. What is the probability of their child having type B blood?

  18. Non-Mendelian Genetics IA IB IAIA = A (1) IAIB = AB (1) Iai = A (1) Ibi = B (1) ¼ or 25% B blood IAIA IAIB IA i IAi IBi

  19. Non-Mendelian Traits • Sex-Linked Traits – traits for which the gene is carried on the X chromosome. • Diseases are more common in malesbecause they only have 1 X chromosome. • Females who are heterozygous for the trait are called carriers • Problem: Colorblindness is a sex-linked recessive trait. If Suzie is a carrier for colorblindness and Joe has normal vision. What is the probability of the two having a son with colorblindness?

  20. Non-Mendelian Traits • Problem: Colorblindness is a sex-linked recessive trait. If Suzie is a carrier for colorblindness and Joe has normal vision. What is the probability of the two having a son with colorblindness? XHXH = normal female (1) XHXh= carrier (1)XHy = normal male (1) Xhy = colorblind male (1) ¼ or 25% of having a son with colorblindness XH Xh XH XHXh XHXH XHy Xhy y

  21. Non-Mendelian Genetics • PolygenicTraits – traits for which the genes are carried in multiple locations on multiple chromosomes. • Results in a wide variety of phenotypes. • Examples: Skin Color & Height

  22. Pedigree • A_pedigreeshows the relationship and inheritance patterns of a family • Males aresquares, females are circles • Unshaded are unaffected, shaded are affected, half shaded are carriers • Horizontal lines between two people indicate matings, vertical lines indicate children • People are numbered from left to right • Generations are numbered going down with Roman Numerals.

  23. Pedigree • Autosomal or Sex-Linked? Dominant or Recessive?

  24. Pedigree • Autosomal or Sex-Linked? Dominant or Recessive?

  25. DNA & Protein Synthesis • DNA Form • Structure of DNA = double helix– discovered by Watson & Crick in 1954 • nucleotides= building blocks • Phosphate • Sugar –Deoxyribose • Nitrogen Base • Adenine & Thymine • Guanine & Cytosine • Nucleotides are held together by weak hydrogen bonds.

  26. DNA & Protein Synthesis Give the complementary DNA Strand • ATAGCATTCCGACGTCAG

  27. DNA & Protein Synthesis Give the complementary DNA Strand • ATAGCATTCCGACGTCAG • TATCGTAAGGCTGCAGTC

  28. DNA & Protein Synthesis • DNA _Replication– DNA makes an exact copy of itself before cell division • DNA molecule separates into 2 strands. • Each strand of DNA serves as a template or model for the new strand. • Two identical DNA molecules are created • DNA replication is aided by the enzymes helicase and DNA polymerase

  29. DNA & Protein Synthesis • RNA Form • RNA is single stranded instead of double stranded like DNA • The sugar deoxyribose is replaced with the sugar ribose. • The base Adenine pairs with Uracilinstead of Thymine

  30. DNA & Protein Synthesis • Types of RNA: • Messenger RNA (mRNA)  brings message from DNA in the nucleus to the ribosome in the cytoplasm. • Transfer RNA (tRNA)  brings correct amino acids to the ribosome to assemble the protein being made. • Ribosomal RNA (rRNA)  the structure of the ribosome

  31. DNA & Protein Synthesis • Protein Synthesis • Transcription= DNA  mRNA, occurs in nucleus • RNA polymerase separates DNA strands and DNA serves as a template for the formation of mRNA. • Transcribe the following: • ATAGCATTCCGACGTCAG

  32. DNA & Protein Synthesis • Transcribe the following: • ATAGCATTCCGACGTCAG (DNA) • UAUCGUAAGGCUGCAGUC (mRNA)

  33. DNA & Protein Synthesis • Translation= mRNA  proteins • Making protein at the ribosome from the mRNA • What sequence of amino acids would make up the protein for the DNA strand above?

  34. DNA & Protein Synthesis • UAUCGUAAGGCUGCAGUC (mRNA) • Split the mRNA into codons (groups of 3) • UAU= ? • CGU= ? • AAG=? • GCU=? • GCA=? • GUC=?

  35. DNA & Protein Synthesis • Now look at your amino acid chart to determine the amino acid that goes with each codon of mRNA • UAU= Tyr • CGU= ? • AAG=? • GCU=? • GCA=? • GUC=?

  36. DNA & Protein Synthesis • UAU= Tyr • CGU= Arg • AAG=Lys • GCU=Ala • GCA=Ala • GUC=Val

  37. DNA & Protein Synthesis • Mutations  any change in a genetic sequence • Creates genetic variation • Harmful mutations are associated with many genetic diseases and some forms of cancer. • Cancer is uncontrolled cell growth or continuous mitosis

  38. DNA Technology • DNA Fingerprint – DNA fragments are run through a gel and bands are compared for similarities • Recombinant DNA – pieces of DNA from 2 different organisms are joined together. • Can be used to produce human insulin for diabetic patients • Cloning – creating genetically identical individuals from a single cell.

  39. DNA Technology • Human Genome Project – identify the genes and sequence bases that make up the human chromosomes. • Completed in 2003 • Information can be used to detect and possibly treat many genetic diseases. • A karyotype is a picture which shows all the chromosomes in each cell • It is used to detect if there are more than two copies of each chromosome and the sex or gender of the individual • 3 copies of Chromosome 21 = Down’s Syndrome

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