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Chromosomes

Chromosomes. Homework. Cell Cycle Review. What are the three big parts of the cell cycle, in order? What happens in each one?. Interphase. Put this diagram in your notebooks (you don’t need the cell pictures or texts). Most of the cell’s life is spent in interphase .

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Chromosomes

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  1. Chromosomes

  2. Homework

  3. Cell Cycle Review • What are the three big parts of the cell cycle, in order? • What happens in each one?

  4. Interphase • Put this diagram in your notebooks (you don’t need the cell pictures or texts) Most of the cell’s life is spent in interphase. Interphase then has some sub-phases, like how “adulthood” is broken down into “young adult,” “mature adult,” “middle-age,” etc.

  5. Interphase G1 (Gap 1) - Cell growth

  6. Interphase G1 (Gap 1) - Cell growth S (Synthesis) - Copy DNA to prepare for later reproduction

  7. Interphase G1 (Gap 1) - Cell growth S (Synthesis) - Copy DNA to prepare for later reproduction G2 (Gap 2) - Lots of protein synthesis, and ensuring “good health”

  8. Interphase G1 (Gap 1) - Cell growth S (Synthesis) - Copy DNA to prepare for later reproduction G2 (Gap 2) - Lots of protein synthesis, and ensuring “good health” G0 (Gap zero) - Resting

  9. Interphase How is interphase analogous to a human life cycle?

  10. Cell Cycle • The cell reproduction that we are talking about at the moment is called: • Asexual reproduction. Just by looking at the term, what do you think it probably means?

  11. Cell Cycle • The cell reproduction that we are talking about at the moment is called: • Asexual reproduction: Reproduction that does not involve two cells fusing together. • Mitosis is asexual reproduction. Why?

  12. Cell Cycle • Asexual reproduction: Reproduction that does not involve fertilization (two cells combining their DNA). Produces offspring genetically identical to the parent. • Mitosis • Other examples include: • Binary fission • Budding • Fragmentation • Parthenogenesis • Spore formation

  13. Cell Cycle • Sexual reproduction: Reproduction in which two cells contribute their chromosomes to create a new cell with a unique genome. • Example: Fertilization of sperm and egg

  14. Chromosomes • Chromosome: A very long, supercoiled strand of DNA. • Different organisms have different numbers of chromosomes in every cell.

  15. Chromosomes • Gene = Region of a chromosome that codes for one protein.

  16. Chromosomes • Different chromosomes carry different genes. • For instance, in humans, everyone has a gene called INSR at the same place on chromosome #19. INSR is a gene that codes for a receptor protein that detects insulin.

  17. Chromosomes • Everyone has two chromosome #19s in each of your cells, so you have two INSR genes. • And two chromosome #1s, two #2s, etc. • Demo

  18. Chromosomes • Homologous chromosomes: Two versions of the same chromosome. They code for all the same proteins, but they may each make those proteins with slightly different sequences and shapes.

  19. Chromosomes • Because we have homolgous chromosomes, meaning two copies of every chromosome, our cells are called diploid. • Latin/Greek Word Roots: Di • Diploid: A cell with 2 copies of each chromosome.

  20. Chromosomes • Diploid: • Haploid: A cell with only 1 copy of each chromosome. • Sperm and eggs only.

  21. Chromosomes • So, a normal diploid human cell has 46 chromosomes: 23 kinds of chromosome, 2 versions of each. • After a human cell undergoes mitosis, how many chromosomes do you think each of the two offspring cells will have?

  22. Chromosomes • Each cell will have 46! They are identical copies of the parent cell, after all.

  23. Chromosomes • To get from one diploid cell with that many chromosomes to two offspring also with that many chromosomes, DNA replication will happen during interphase. • Find three people, and explain to them how DNA replication works.

  24. Chromosomes • DNA Replication • A strand of DNA “unwinds” and “unzips” • Extra DNA nucleotides are attached to their base pair partners • This creates two DNA molecules that are entirely identical to each other • Keep this in mind for the future.

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