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Module B Review

Module B Review. Part One. 15. 1. 2. 13. 7. 12. 11. 10. 8. 9. 3. 5. 4. 14. 6. Cells divide at different rates. The rate of cell division varies with the need for that type of cell. Some cells are unlikely to divide (in Gap 0/G0 of the cell cycle) Example: neurons.

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Module B Review

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  1. Module B Review Part One

  2. 15 1 2 13 7 12 11 10 8 9 3 5 4 14 6

  3. Cells divide at different rates. • The rate of cell division varies with the need for that type of cell. • Some cells are unlikely to divide (in Gap 0/G0 of the cell cycle) • Example: neurons

  4. Cell size is limited. • Volume increases faster than surface area. • Cells need to stay small to allow diffusion and osmosis to work efficiently.

  5. Mitosis and cytokinesis produce two genetically identical daughter cells. • Interphase prepares the cell to divide. • During interphase, the DNA is duplicated.

  6. Mitosis divides the cell’s nucleus in four phases. • Prophase • Chromosomes condense, spindle fibers form, and the nuclear membrane disappears

  7. Mitosis divides the cell’s nucleus in four phases. • Metaphase • Chromosomes line up in the middle of the cell

  8. Mitosis divides the cell’s nucleus in four phases. • Anaphase • Sister chromatids are pulled apart to opposite sides of the cell

  9. Mitosis divides the cell’s nucleus in four phases. • Telophase • Two nuclei form at opposite ends of the cell, the nuclear membranes reform, and the chromosomes uncoil back into chromatin

  10. Cytokinesis differs in animal and plant cells. • Cytoplasm separates • Animal cells: membrane pinches the two new cells apart • Plant cells: a cell plate (new cell wall) separates the two new cells

  11. Cell division is uncontrolled in cancer. • Cancer cells form disorganized clumps called tumors. • Benign tumors remain clustered and can be removed. • Malignant tumors metastasize, or break away, and can form more tumors.

  12. 5.4 – Asexual Reproduction • Key Concept: • Many organisms reproduce by cell division.

  13. Binary fission is similar to mitosis. • Asexual reproduction is the creation of offspring from a single parent. • Binary fission produces two daughter cells genetically identical to the parent cells. • Binary fission occurs in prokaryotes.

  14. Some eukaryotes reproduce by mitosis. • Budding forms a new organism from a small projection growing on the surface of the parent. • Fragmentation is the splitting of the parent into pieces that each grow into a new organism. • Vegetative reproduction forms a new plant from the modification of a stem or underground structure on the parent plant.

  15. Multicellular organisms depend on interactions among different cell types. • Tissues are groups of cells that perform a similar function. • Organs are groups of tissues that perform a specific or related function. • Organ systems are groups of organs that carry out similar functions.

  16. Specialized cells perform specific functions. • Cells develop into their mature forms through the process of cell differentiation. • Cells differ because different combinations of genes are expressed. • A cell’s location in an embryo helps determine how it will differentiate.

  17. 6.1 – Chromosomes & Meiosis • Key Concept: • Gametes have half the number of chromosomes that body cells have.

  18. You have somatic cells and gametes. • Somatic Cells: • Are body cells • Make up all cells in body except foregg and sperm cells • Not passed on to children • Gametes: • Are egg or sperm cells • Passed on to children

  19. Your cells have autosomes and sex chromosomes. • Somatic cells have 23 pairs of chromosomes (46 total) • (1) Autosomes: pairs 1 – 22; carry genes not related to the sex of an organism • (2) Homologous chromosomes: pair of chromosomes; get one from each parent; carry the same genes but may have a different form of the gene (example: one gene for brown eyes and one gene for blue eyes) • (3) Sex chromosomes: pair 23; determines the sex of an animal; control the development of sexual characteristics

  20. Somatic cells are diploid; gametes are haploid. • Diploid (2n) • Has two copies of each chromosome (1 from mother & 1 from father) • 44 autosomes, 2 sex chromosomes • Somatic cells are diploid • Produced by mitosis • Haploid (1n) • Has one copy of each chromosome • 22 autosomes, 1 sex chromosome • Gametes are haploid • Produced by meiosis

  21. Meiosis I • Occurs after DNA has been replicated (copied) • Divides homologous chromosomes in four phases.

  22. Meiosis II • Divides sister chromatids in four phases. • DNA is not replicated between Meiosis I and Meiosis II.

  23. Mitosis Vs. Meiosis Mitosis Meiosis Two cell divisions Homologous chromosomes pair up (Metaphase I) Results in haploid cells Daughter cells are unique • One cell division • Homologous chromosomes do not pair up • Results in diploid cells • Daughter cells are identical to parent cell

  24. Sexual reproduction creates unique combinations of genes. • Fertilization • Random • Increases unique combinations of genes • In humans, the chance of getting any one combination of chromosomes from any one set of parents is one out of 223 x 223 (which is one out of over 64 trillion combinations)

  25. Sexual reproduction creates unique combinations of genes. • Independent assortment of chromosomes • Homologous chromosomes pair randomly along the cell equator • Increases the number of unique combinations of genes • In human cells, about 223 (8 million) different combinations could result

  26. Sexual reproduction creates unique combinations of genes. • Crossing over • Exchange of chromosome segments between homologous chromosomes • Increases genetic diversity • Occurs during Prophase I of Meiosis I • Results in new combinations of genes (chromosomes have a combination of genes from each parent)

  27. There are 4 types of nucleotides: thymine, adenine, cytosine, and guanine • The nitrogen containing bases are the only difference in the four nucleotides.

  28. nucleotide The DNA molecule unzips in both directions. Proteins carry out the process of replication. • DNA serves only as a template. • Enzymes and other proteins do the actual work of replication. • Process 1. Enzymes unzip the double helix. 2. Free-floating nucleotides form hydrogen bonds with the template strand.

  29. 2. Nitrogen bases 4. new strand 3. DNA polymerase • 3. DNA polymerase enzymes bond the nucleotides together to form the double helix. 1. Sugar Phosphate Backbone

  30. new strand original strand Two molecules of DNA 4. Two new molecules of DNA are formed, each with an original strand and a newly formed strand. • DNA replication is semi-conservative, meaning one original strand and one new strand.

  31. RNA differs from DNA in three major ways. • DNA has a deoxyribose sugar, RNA has a ribose sugar. • RNA has uracil instead of thymine (found in DNA) • A pairs with U • DNA is a double stranded molecule, RNA is single-stranded.

  32. transcription complex start site 5. nucleotides • 1. Transcription is catalyzed by RNA polymerase. • RNA polymerase and other proteins form a transcription complex. The transcription complex recognizes the start of a gene and unwinds a segment.

  33. 6. RNA The RNA strand detaches from the DNA once the gene is transcribed.

  34. codon for methionine (Met) codon for leucine (Leu) Amino acids (protein building blocks) are coded for by mRNA base sequences. • A codon is a sequence of three nucleotides that codes for an amino acid.

  35. The genetic code matches each RNA codon with its amino acid or function. • The genetic code matches each codon to its amino acid or function. • three stopcodonssignal the end of a chain of amino acids. • one startcodon, codes for methionine and to start translation

  36. 1. For translation to begin, tRNA binds to a start codon (Met in picture) and signals the ribosome to assemble. • A complementary tRNA molecule binds to the exposed codon (Leu in picture), bringing its amino acid close to the first amino acid.

  37. mutated base Some mutations affect a single gene, while others affect an entire chromosome. A gene mutation affects a single gene. • Many kinds of mutations can occur, especially during replication. Types of Gene Mutations: • A point mutation substitutes one nucleotide for another. Ex: Sickle Cell Anemia

  38. Nonsense Mutation • Type of point mutation • Results in a premature stop codon and usually a nonfunctional protein

  39. A frame-shift mutation inserts or deletes a nucleotide in the DNA sequence. Throws off the reading frame. • THE CAT ATE THE RAT • THC ATA TET HER AT

  40. Chromosomal mutations affect many genes and an entire chromosome. Chromosomal mutations may occur during crossing over.

  41. Deletion • Due to breakage • A piece of a chromosome is lost

  42. Inversion • Chromosome segment breaks off • Segment flips around backwards • Segment reattaches

  43. Translocation results from the exchange of DNA (piece of one chromosome) segments between non-homologous chromosomes.

  44. Nondisjunction • Failure of chromosomes toseparate during meiosis • Causes gamete to have too many or too few chromosomes

  45. Nondisjunction • Can cause “Trisomy” (three copies of the same chromosome in an egg or sperm) • Trisomy 21 (Down syndrome)

  46. Gene duplication results from unequal exchange of segments crossing over. Results in one chromosome having 2 copies of some genes and the other chromosomes having no copies of those genes.

  47. X Y Several methods help map human chromosomes. • A karyotype is a picture of all chromosomes in a cell.

  48. 9.1: Manipulating DNA • Key Concept: • Biotechnology relies on cutting DNA at specific places.

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