BI 233 A&P Lab-Ex. 45

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BI 233 A&P Lab-Ex. 45
2012-11-27 22:09:44
pcc anatomy physiology lab ex 45 exercise principles heredity

Principles of Heredity
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  1. Diploid Number
    46 chromosome pairs contained in all human cells (except sperm/egg); maintained via mitosis
  2. Haploid Complement
    23 chromosomes contained in each gamete
  3. Homologous Chromosomes
    Chromosomes which have the same genes, but possibly different alleles
  4. Allele
    Genes having a specific position on a specific chromosome, which code for a specific trait
  5. Heterozygous
    Trait in which the pair of alleles (on the homologous chromosomes) differ
  6. Homozygous
    Trait in which the pair of alleles (on the homologous chromosomes) match/have the same expression
  7. Gene
    The element of a chromosome which provides the code for a particular trait
  8. Dominant Allele (dominanat gene)
    The allele which exerts its effects whether it is part of a hetero- or homo- zygous pair
  9. Recessive Allele (recessive gene)
    Gene which will be suppressed in the case of a heterozygous pair
  10. Genotype
    The genetic makeup of an individual;whether she is hetero- or homo- zygous
  11. Phenotype
    The manner in which a genotype is expressed (physical expression of a genotype)
  12. Monohybrid Cross
    The cross of a single genetic trait with two alleles
  13. Individual who discovered that each gamete contributes just one allele to each pair in the zygote
    Gregor Mendel--and Austrian monk of the mid-1800s
  14. Punnett Square
    Grid or diagram which provides a simple framework for determining a genotype by hand

  15. Incomplete Dominance (Intermediate Inheritance)
    • Condition in which the recessive gene is only partially repressed
    • Condition in which both alleles express themselves in the offspring thus producing an intermediate phenotype
    • Condition in which so-called dominant genes may be expressed differently in homo- and hetero- zygous offspring
  16. Co-Dominance
    Condition in which each cell or cell component "chooses" one or the other phenotype (e.g. variagated leaf; calico cat--orange, black, or white) or "chooses" both phenotypes (e.g. AB blood)
  17. SCA
    • Sickle Cell Anemia--disease produced due to incomplete dominance
    • SS--(sickling gene absent) porduce normal hemoglobin
    • Ss--(heterozygous) Sickle Cell Trait (SCT) produce both normal and sickling hemoglobin; develop anemia only in prolonged cases of O2 deficit
    • ss--(homozygous, exhibit SCA) produce abnormal hemoglobin which crystallizes and becomes sharp/spiky under O2 deficit clumping, pain, possible death
  18. Autosome
    • 22 of the 23 pairs of homologous chromosomes which determine most body (somatic) characteristics
    • (do not determine sex, or sex-linked characteristics)
  19. Sex Chromosome
    • 23rd pair of homologous chromosomes which determine the sex of an individual
    • XY=♂; XX=♀
    • The Y chromosome, which determines maleness, is ~1/3 the size of the X chromosome and lacks many of the genes
  20. Sex-Linked Genes
    • Genes present on either the X or Y chromosome, thus the phenotype requires only one recessive gene to present in males, but requires two (homozygous) recessive genes to present in females
    • E.g. normal color vision (color blindness=recessive), normal clotting ability (hemophilia=recessive)
  21. Holandric
    Genes which occur only on the Y chromosome and thus are only exhibited in males
  22. Male Transmission of Sex-Linked Genes
    • The father will always pass his X to a daughter and his Y to a son
    • Males (XY) always inherit sex-linked conditions from their mothers
    • Females (XX) may inherit sex-linked conditions from either their mother or father
    • Males (XY) may inherit holandric conditions from their father
    • Females (XX) may not inherit holandric conditions
  23. Probability

    An event with a probability of 1 is certain to happen
  24. Probability of consecutive events (events which occur together)
    • Mathematical product of all individual events
    • E.g. the probability of getting heads 4 times in a row