Chapter 11

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Chapter 11
2011-11-17 17:16:44
Bio 196

Inheritance, Genes, and Chromosomes
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  1. What is the phenotype?
    The physical appearance of an organism.
  2. What is the genotype?
    The genetic information (alleles) of an organism.
  3. What are the Pre-Mendelian Laws of Inheritance?
    - Each parent contributes equally to the offspring (proven correct by experimentation.)

    - Hereditary determinants blend in offspring (proven incorrect.)
  4. What generations are involved in genetic crosses?
    • The P (parent) generation.
    • The F1 (first filial) generation.
    • The F2 (second filial) generation.
  5. What is the Character?
    An observable physical feature.

    ex. Color.
  6. What is a trait?
    A particular form of a character.

    ex. purple color vs white color.
  7. What is a heritable trait?
    A trait that is passed from the parent to the offspring.
  8. What does is mean for traits to be true-breeding?
    It means that the observed trait was the only one to show up for many generations.
  9. What is a mono-hybrid cross?
    When two true-breeding P (parent) generations differing in just one trait are crossed, producing a monohybrid F1 generation.
  10. In Mendel's experiment, which pea seed trait was dominant?
    The smooth, spherical seed shape.
  11. In Mendel's experiment, which pea seed trait was recessive?
    The wrinkled seed trait.
  12. What ideas led to the rejection of Mendel's blending theory?
    If "blending" occurred, then the F1 generation would have shown intermediate traits between the two P generations, since one was wrinkled and the other was smooth. The F1 generation would have been slightly wrinkled, yet it was not. Also, the F2 generation had a re-occurrance of the recessive trait after its absence in F1. This led to the particulate theory.
  13. The particulate theory states that,
    the units of inheritance retain their integrity even in the presence of other units.

    Each pea plant has two different units (or particles) of inheritance for each character, one from each parent.
  14. What is diploid?
    Two copies of each heritable unit of an organism.

    During the production of gametes, only one of these paired units are given to the next generation of gametes.
  15. What is haploid?
    the single set of heritable units.

    The resulting zygote contains two, because it is made by the fusion of two gametes. One from each parent.
  16. What is a gene?
    Mendel's unit of inheritance.
  17. What is a genome?
    The totality of all an organism's genes.
  18. What are alleles?
    Different forms of a gene.

    Ex. S and s.
  19. What is a homozygous allele?
    When there are two copies of the same allele.

    Ex. SS or ss
  20. What is a heterozygous allele?
    There are two different copies of alleles in a gene.

    Ex. Ss
  21. What is Mendel's 'Law of Segregation'?
    • Every individual in the offspring from a cross between two P generations receives one gene copy from each parent.
    • So, if one P generation is SS and the other is ss, then the F1 generation will be Ss because each P generation's gamete's genes were separated.
  22. What is a Punnett square?
    It is used to find the allele combinations the result from a cross.
  23. What is a test cross?
    • Is used to find out whether an individual that shows a dominant trait is homozygous or heterozygous.
    • The individual is crossed with an individual that is homozygous recessive for the same trait. If the dominant individual is homo, then the F1 gen will be all hetero. Is the dominant individual it hetero, then a few of the F1 will have the possibility of being homo recessive.
  24. What is a dihybrid cross?
    A cross between individuals that identically double heterozygous.

    Both are SY, Sy, sY, and sy.
  25. What is the 'Law of Independent Assortment'?
    Alleles of different genes assort independently of one another during gamete formation. So, A alleles are independent of B alleles. This applies to genes that are on different chromosomes.
  26. Cell division in prokaryotic and eukaryotic cells consist of what 4 steps?`
    • Reproductive Signal
    • Replication of DNA
    • Segregation
    • Cytokinesis
  27. What happens during replication?
    Causes the two new cells to have identical genes and complete all cell functions.
  28. What happens during segregation?
    Distribution of the replicated DNA to the two new cells.
  29. What is Mitosis?
    A mechanism that causes one nucleus to be segregated into two identical nuclei.
  30. What is Meiosis?
    The process of nuclear division that occurs in cells during sexual reproduction that turns two parent cells into four un-identical daughter cells.
  31. What is the Eukaryotic cell cycle?
    Two main phases: Interphase and M-phase

    • Interphase consists of 3 sub-phases.
    • S phase- DNA replicates
    • G1 phase- prepares for S phase
    • G2 phase- prepares for mitosis

    M-phase- mitosis and cytokenisis
  32. What is the CDK-complex?
    • Checkpoints in the cell cycle that regulates the cell's progress.
    • It regulates...
    • -the entry into M and progress through M
    • -G1-S entry into the R (restriction point).

    The process through the cell cycle depends on the activity of cdks (cyclin-depend kinases)
  33. What happens during mitosis?
    • PMAT
    • Interphase
    • Prophase- the beginning of mitosis. The chromosomes consist of identical, paired sister chromatids. The Centrosomes move to opposite poles.
    • Prometaphase- The nuclear envelope breaks down. The chromosomes consisting of two chromatids attach to the kinetochore microtubules.
    • Metaphase- The chromosomes line up at the midline of the cell.
    • Anaphase- The chromatids separate and move away from each other toward the poles.
    • Telophase- The nuclear envelope and the nuclei re-form around each set of chromosomes so that there are two new nuclei in a single cell.
  34. What are the overall functions of Meiosis?
    • To reduce the chromosomes number from diploid to haploid.
    • To ensure that each of the haploid products has a complete set of chromosomes.
    • To generate genetic diversity among the products.
  35. What features characterize Meiosis 1?
    • Homologous chromosomes come together to pair along their entire lengths.
    • The homologous chromosome pairs separate, but the individual chromosomes, each consisting of two sister chromatids, remain intact.
  36. Asexual reproduction
    • A single celled organism divides only by mitosis.
    • Produces organisms that are clones. They are genetically identical to their parent organism.

    Any genetic variation from the offspring will be because of small environmentally caused changes in the DNA, called mutations.
  37. Sexual reproduction
    Results in an organism that is not identical to the parents. Happens by meiosis. Both parents contributes one gamete to the offspring. Fertilization forms a diploid zygote.

    Genetic variations allow offspring to be better adapted to the environment to survive and reproduce.
  38. In a living organism, how to cells die?
    They die by necrosis, when cells are damaged because mechanical means, toxins, or starved of oxygen or nutrients. Or it can self-destruct by apoptosis, a genetically programmed series of events that include the fragmentation of its nuclear DNA.