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32. Cell Cycle Events

Learn about the different phases of the cell cycle, from interphase to cytokinesis. Understand the processes of cell division, such as prophase, metaphase, anaphase, and telophase. Discover the importance of DNA replication and the formation of new cells.

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32. Cell Cycle Events

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  1. 32. Cell Cycle Events Interphase Cell Division Prophase- chromosomes Metaphase- Chromosomes align along the metaphase plate (middle) Anaphase- sister chromatids separate Telophase- Cleavage furrow begins and nuclear envelopes reform. Cytokinesis- division of the cytoplasm (two new cells) • Longest phase of the cell cycle. • DNA is in chromatin form • G1- Growth (organelles duplicate) • S- replication (duplication) or DNA • G2- Cell Growth

  2. 33. If a skin cell had 52 chromosomes, how many chromosomes would be found in an egg cell? 26

  3. 34.) Compare and contrast mitosis and meiosis Mitosis Meiosis ds ds Only once through division cycle Goes through division cycle twice Go through interphase (cell growth) majority of time At anaphase 1, Homologous chromosomes separate At anaphase, sister chromatids separate Go through PMAT (second division of meiosis is similar to mitosis) At cytokinesis, two identical cells separate At cytokinesis 1, two haploid daughter cells are formed Chromsosome # is half of the original cell and a UNIQUE combination Chromosome # is identical as the original cell TWO IDENTICAL DIPLOID CELLS Makes BODY (somatic) cells FOUR UNIQUE HAPLOID CELLS Makes GAMETES (egg and sperm)

  4. 35. Non-disjunction • Nondisjunction is the failure for duplicated chromosomes to separate • Generally during Meiosis II • Down syndrome is also known as TRISOMY 21. • Three copies of the 21st chromosome

  5. 36. Describe the shape and composition of a DNA molecule • Shape: Double Helix • Composition: • Phosphate group • Deoxyribose sugar • 1 of 4 nitrogen bases http://ghr.nlm.nih.gov/handbook/basics/dna

  6. 37. What is the function of DNA? • The function of DNA is to store heredity information that will be passed down to generations. It also contains the code for generating mRNA; this will eventually lead to tRNA, rRNA, and eventually proteins.

  7. 38) Base Pairing • A-T (adenine to thymine) • C-G (cytosine to guanine) • Bonded by hydrogen bonds • 2 bonds between A and T • 3 bonds between C and G

  8. 39) DNA vs. RNA DNA RNA A,U,C,G Ribose sugar Single Strand Less complex • A,T,C,G • Deoxyribose sugar • Double helix • More complex

  9. 40) Codons • Set of threenucleotides on the mRNA strand • Instructions for amino acids which then leads to protein production • Codes for amino acids • 3 letters make up a codon

  10. 41) mRNA sequence • mRNA: UUC GUU GGA ACC • DNA: AAG CAA CCT TGG • Amino acid: Phe-Val-Gly-Thr

  11. 42 a. Point Mutations • Substitution • Point where one nitrogen base is substituted for another • Sickle Cell Anemia: substitute A for T

  12. 42 b. Frame Shift Mutations • Deletions and Insertions • When a nitrogen base is deleted or added • Frame shift mutations- because it moves the codon up or down • Changes the sequence of amino acids after the mutation

  13. 43) Transcription vs. Translation Transcription Translation RNA to protein Occurs in cytoplasm • DNA to RNA • Occurs in nucleus

  14. 44.) Define the following terms: • Genotype: The genetic makeup of an organism • Phenotype: The physical traits of an organism • Homozygous: Having two identical alleles for a given gene • Heterozygous: Having two different alleles for a given gene • Dominant: In a heterozygote, the allele that determines the phenotype with respect to a particular gene (the larger letter) • Recessive: In a heterozygous individual, the allele that has no noticeable effect on the phenotype (the smaller letter)

  15. 45. How are the following words related? DNA, gene, RNA, protein, trait • Gene (stretch of DNA) that is transcribed into RNA, that is translated into PROTEIN, that is expressed as a TRAIT

  16. 46. Punnett Square • tool used to determine the probability of traits being passed on to offspring based on parents genotypes • Parents genotypes represent egg and sperm • Offspring's genotypes represent body cells

  17. 47. a)Monohybrid Heterozygote Parents (Tt x Tt)b) Blonde hair is dominant to brown. Two parents are mated one with blonde hair and one with brown, and some of their children end up with blonde and some with brown. a) b) Parent 1- Bb Parent 2- bb

  18. 48. • Children born with a recessive genetic disorder can have parents that do not express the disorder, because the parents are heterozygous. • The parents have the gene for the disorder, but it is masked by the dominant gene. • This is how some traits can “skip” a generation.

  19. 49. Gene Pool • Gene pool is the available genes in a breeding population.

  20. 50. • Species can achieve genetic variation over many generations by breeding outside of the immediate family. • No inbreeding • This allows new genes to be introduced

  21. 51. • A species can loose genetic diversity overtime by not “adding” to the gene pool. • Inbreeding • No gene shuffling

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