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Lesson 128

Lesson 128. Learning Goal: (You should be able to…) Describe how the amount of DNA kept the same from generation to generation. Explain why you don’t have twice as much DNA in each of your cells as your parents do. Success Criteria: (Can you …) Describe a human cell karyotype

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Lesson 128

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  1. Lesson 128 Learning Goal: (You should be able to…) Describe how the amount of DNA kept the same from generation to generation. Explain why you don’t have twice as much DNA in each of your cells as your parents do. Success Criteria: (Can you …) Describe a human cell karyotype Describe the purpose of meiosis Describe how a zygote is formed Describe the pattern of chromosomes in various types of cells

  2. In your binder lesson 128 Notes on karyotype Paragraph answering the following: “How is the amount of DNA kept the same from generation to generation?” “Why don’t you have twice as much DNA in each of your cells as your parents do?”

  3. Essential Questions • How do living organisms pass on their traits? • How do the laws of genetics help predict the possible expression of certain traits? • How do malfunctions affect the system of inheritance?

  4. Genetics Vocabulary Allele Dominant allele Recessive allele Homozygous, Purebred Heterozygous, Hybrid Co dominant alleles Incomplete dominant alleles Meiosis Gamete, Sex cell Fertilization Zygote Chromosome Gene Karyotype Genotype Phenotype

  5. Write to Think 128 • What is a chromosome made of? • What’s the ‘relationship’ between a DNA sequence or code, a gene, and a chromosome? • How do you think your genetic make up (DNA, genes, chromosomes) compares with your parents genetic make up ?

  6. Plan of action • Note taking organizer • Purpose … read the information at the top! • Direct instruction/foreshadow • Karyotype modelling(Playing card analogy) • Karyotype picture analysis & Recall/Notes • Meiosis and gamete modelling (Playing card analogy) • Meiosis information & Recall/Notes • Zygote modelling (Playing card analogy) • Zygote information & Recall/Notes • Write one or two paragraphs!

  7. Describe how the amount of DNA is kept the same from generation to generation. Explain why you don’t have twice as much DNA in each of your cells as your parents do.

  8. Meiosis 46 C (23 pairs) 23 C 1 of each pair 23 C 1 of each pair GAMETES or SEX CELLS (sperm or eggs). Each new cell has only half (23) the number of chromosomes (46) and NO PAIRS!

  9. Zygote formation 23 C 1 of each pair 23 C 1 of each pair From Dad From Mum SEX CELL or GAMETE or EGG or OVUM SEX CELL or GAMETE or SPERM 46 (23 pairs) ZYGOTE and after lots of cell cycles …

  10. Modelling chromosomes with …. Playing cards! • Brand new … don’t fold or crease or mark please! • The envelope is ONE cell from an organism • The cards represent chromosomes. • How many ‘chromosomes’ does each cell of your organism have? • Describe as many patterns in the ‘chromosomes’ as you can find in the next 3 minutes. • Discuss!

  11. What is this? What can you see? What can you infer?

  12. Human Karyotype of ONE cell at the beginning of telophase

  13. Questions … active recall … Notes? • How many chromosomes are there in human cells? • How many PAIRS of chromosomes? • What is similar about the chromosomes in ONE pair? • What do the chromosomes contain? • Is it necessary to have ALL the chromosomes?

  14. Modelling meiosis and gamete formation with …. Playing cards! • Pair up the “chromosomes’ • One from EACH pair into a new cell • How many new cells? These are gametes! • How is each new cell different from the original? • How is each new cell similar to the original? • The result of meiosis is ….

  15. Questions … active recall … Notes? • How many new cells? • How is each new cell different from the original? • How is each new cell similar to the original? • The result of meiosis is ….

  16. Modelling zygote formation with …. Playing cards! • Find a group in front or behind you with similar ‘chromosomes’ • Each group make ‘gametes’. (Split the pairs) • Make a zygote by ‘joining’ two gametes from DIFFERENT organisms/groups. (fertilization) • How is the new zygote different from the original two gametes? • How is the new zygote different from the original two organisms cells? • How is the new zygote similar to the original two gametes? • How is the new zygote similar to the original two organisms cells?

  17. Questions … active recall … Notes? • How many new cells from one fertilization? • How is the new zygote different from the original two gametes? • How is the new zygote different from the original two organisms cells? • How is the new zygote similar to the original two gametes? • How is the new zygote similar to the original two organisms cells?

  18. Meiosis • 46 C • (23 pairs) • 23 C • 1 of each • pair • 23 C • 1 of each • pair • GAMETES or SEX CELLS (sperm or eggs). • Each new cell has only half (23) the number of chromosomes (46) and NO PAIRS!

  19. Zygote formation 23 C 1 of each pair 23 C 1 of each pair From Dad From Mum SEX CELL or GAMETE or EGG or OVUM SEX CELL or GAMETE or SPERM 46 (23 pairs) ZYGOTE and after lots of cell cycles …

  20. So … • Write one or two paragraphs that explains the following: “How is the amount of DNA kept the same from generation to generation?” “Why don’t you have twice as much DNA in each of your cells as your parents do?”

  21. End of lesson

  22. Human Karyotype in Prophase

  23. Questions … active recall

  24. Human Karyotype • 46 chromosomes (In interphase, G1 and/or G0 uncondensed) • DNA sequences …. 1000’s of bases • Specific location for each characteristic (colored bands) • 100’s of genes in each chromosome • Numbered 1 to 22 and sex chromosomes • 23 pairs (1m, 1d … 2m, 2d) • NOT to be confused with the copies in S Phase • A pair is two chromosomes that are similar (like shoes) • In prophase and telophase condensed

  25. Questions … active recall

  26. How many shoes?

  27. 1 6 11 16 2 7 17 12 3 8 13 18 4 9 14 19 5 10 15 20

  28. How many shoes? • 40 shoes • 20 different pairs of shoes • Each one (L and R) in a pair is similar BUT not identical! • Need all 40 for a set!

  29. Human Karyotype: 46 chromosomes, 22 pairs and a ‘sex’ pair 1m 1d 2m 2d 3m 3d 4m 4d 14m 14d ..m ..d 22m 22d X y 1m 1d 2m 2d 3m 3d 4m 4d 14m 14d ..m ..d 22m 22d X X Female (46) OR Male (46)

  30. What is this? What can you see? What can you infer?

  31. Meiosis and gamete formation • Study the diagram across the top of pages 94 and 95. • With your partner answer the following: • What is it? • What do you see? • What can you infer? • How’s it different from mitosis?

  32. Meiosis and gamete formation • Purpose of meiosis: • To prepare organisms for sexual reproduction where only half of each parents DNA is passed on to their offspring. • Cells go through cell division to create new cells • Meiosis prepares organisms for sexual reproduction • Meiosis halves the chromosome number in each of the new cells (gametes, sex cells) • Gametes (eggs and sperm, sex cells) in humans have a total of 23 chromosomes BUTNO PAIRS!! • All other human cells have a total 46 chromosomes, 23 PAIRS. • Result of meiosis: • New cells with HALF the number of chromosomes, NO PAIRS, 23 different chromosomes #’s 1 to 23.

  33. Write to Think ??? • Copy the following (in green below) onto a piece of lined paper. (You’ll be using the paper to take notes on today and tomorrow!) “How is the amount of DNA kept the same from generation to generation?” “Why don’t you have twice as much DNA in each of your cells as your parents do?” 2. Read and study the picture (karyotype) on your lab bench. What is it? What do you observe? What can you infer?

  34. Questions … active recall

  35. Meiosis • 46 • (23 pairs) • 23 • 1 of each • pair • 23 • 1 of each • pair • 23 • 1 of each • pair • 23 • 1 of each • pair • 4 GAMETES or SEX CELLS (sperm or eggs). • Each new cell has only half (23) the number of chromosomes (46) and NO PAIRS!

  36. Meiosis and gamete formation • Purpose of meiosis: • To prepare organisms for sexual reproduction where only half of each parents DNA is passed on to their offspring. • Cells go through 2 cell divisions to create four cells • Meiosis prepares organisms for sexual reproduction • Meiosis halves the chromosome number in each of the four new cells (gametes, sex cells) • Gametes (eggs and sperm, sex cells) in humans have a total of 23 chromosomes BUTNO PAIRS!! • All other human cells have a total 46 chromosomes, 23 PAIRS. • Result of meiosis: • Four cells with HALF the number of chromosomes, NO PAIRS, 23 different chromosomes #’s 1 to 23.

  37. Questions … active recall • 6 chromosomes (human has 46) • 3 pairs (human has 23) • The pairs are SIMILAR but NOT identical • Both chromosomes in a pair have SIMILAR information but not identical! • Gene = characteristic (Eye color) • Allele = trait (Brown)

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