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Life Science CST Prep

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  1. Life Science CST Prep Mr. McCabe and his former students!

  2. DIP SOB MITO HAP SEG MEIO

  3. DIP SOB MITO Diploid Somatic/Body Mitosis

  4. HAP SEG MEIO Haploid Sex/Germline Meiosis

  5. 23 46 HAP SEG MEIO DIP SOB MITO

  6. Mitosis Meiosis 1 Round of Division 2 Cells Made/Produced Cells are diploid No tetrads (pairs of 4) No crossing over 2 Rounds of Division 4 Cells Made/Produced Cells are haploid Prophase I has Tetrads (pairs of 4) Crossing over

  7. Cell Division Mitosis Meiosis

  8. PMAT Prophase  Pairing Metaphase  Middle Anaphase  Apart Telophase Two nuclei/cells

  9. Crossing Over • To make more combinations of gametes • This is done during prophase I of meiosis when chromosome arms switch places

  10. Genetics

  11. Gene • Part of DNA that makes a trait • Allele • The different kinds/versions of the trait

  12. Genotype • How we write the DNA • Phenotype • How the trait looks

  13. Zygosity Homozygous Heterozygous Cell gets the same allele from each parent BB, dd, FF, jj Cell gets a different allele from each parent Bb, Dd, Ff, Jj

  14. Dominance Dominant Recessive Cell needs only one copy of a dominant allele to have a dominant phenotype BB, Dd, FF, Jj Cell needs two copies of a recessive allele to have a recessive phenotype bb, dd, ff, jj

  15. Vocab • Homozygous • Organism has the same allele from both parents • Heterozygous • Organism has different alleles from both parents • Dominant • Only one copy of the gene is needed • Hides the recessive allele • Recessive • Requires two copies of the gene

  16. Central Dogma • DNA  RNA  Protein

  17. DNA Replication • DNA  DNA • A binds T • T binds A • G binds C • C binds G

  18. Mutations • A change in the type, number or order of nucleotide bases

  19. DNA Mutations Frameshift Point Mutation Frameshift mutations Any number of bases are added or deleted. This can throw off the codon reading frame Point Mutations Point mutations are when just one nucleotide gets changed to another. May or may not have a large effect.

  20. Amino Acid Effects • Silent Mutation • A mutation in which no amino acid change happens • Missense Mutation • A mutation in which the amino acid gets switched • Nonsense Mutation • A mutation in which the protein gets stopped early

  21. Inheritance • Inheritance is how we pass on traits from one generation to the next P  F1 F2

  22. Human Chromosomes • 23 different chromosomes • 22 autosomal chromosomes • 1 set of sex chromosomes

  23. Sex Chromosomes Females are “XX”Males are “XY”

  24. Male XY XX XY X X Female XX XY

  25. Mode of Inheritance • Mode of inheritance • What type of chromosomes we will find the gene/trait on. • 2 Types • Autosomal • Sex-linked

  26. Mode of Inheritance • Autosomal • Traits found on chromosomes 1-22 (most traits) • Sex-linked • Traits found on either of the sex chromosomes (X or Y)

  27. Some terminology…. • We write autosomal with regular letters. Aa AA Aa A a Aa aa

  28. Some terminology…. • We write X-linked like this: XhY XHXh XHY XH Xh XhXh XhY

  29. Some terminology…. • We write Y-linked like this: XYt XX XYt X X XX XYt

  30. Think-Pair-Share Sex linked traits are more likely to affect males. Why do you think this is?

  31. hemizygous • Males are hemizygous. • Since males only have one X and one Y, they only need one copy to be dominant or recessive • Since females do not have a Y, they cannot be affected by Y linked traits/diseases.

  32. Dominance?

  33. And Announcing….. • Born last night • 10.2 oz. • 22 ½ inches long • 15.5 inch head diatmeter TRISTAN ALEXANDER MCCABE

  34. What we know • We have two alleles of each trait: the dominant allele (A) and the recessive allele (a) • The dominant allele always hides the recessive allele • This is called “complete dominance”

  35. Baking a Cake

  36. Different rules of Dominance • Sometimes genes don’t follow the dominant/recessive rules of dominance. • There are other ways to inherit traits • Incomplete dominance and codominance.

  37. Today’s Example Red flower x White flower AA aa X

  38. Parent 1 a a A Parent 2 A

  39. Complete Dominance Complete Dominance • The dominant allele always covers the recessive allele for phenotypes • AA = Dominant phenotype • Aa = Dominant phenotype • aa = Recessive phenotype

  40. Parent 1 Complete Dominance a a A Aa Aa Parent 2 A Aa Aa

  41. Incomplete Dominance Incomplete dominance • Instead of 2 phenotypes, we see 3 • Red Flowers + White Flowers = Pink Flower

  42. Parent 1 Incomplete Dominance a a A Aa Aa Parent 2 A Aa Aa

  43. Codominance Codominance • Both the dominant and recessive allele are shown but they are not mixed together • Red + white flowers = flower with red and white spots

  44. Parent 1 Co-dominance a a A Aa Aa Parent 2 A Aa Aa

  45. Different Rules of Dominance Complete Dominance Incomplete Dominance Co- dominance

  46. Different Rules of Dominance Codominance • Blood is co-dominant • There are three alleles: A, B and i

  47. Natural Selection • The process in which the environment determines what traits are beneficial and should be passed onto future generations • Ex: Peppered Moth