Chapter 3 ppt

  1. What is a monohybrid?
    What is a dihybrid?
    From studying what did mendel use to come up with his second principle of heredity?
    A monohybrid is a heterozygote for a single gene such as A/a.

    • A dihybrid is a double heterozygote.
    • A dihybrid cross.
  2. For a monohybrid cross for seed color (Y/y x Y/y), which gave a progeny ratio of what to what?
    What is an example of a gamete?
    What is the F1?
    What is Mendel's second law?
    For two heterozygous pairs, what is likely to happen in b, A/a and B/b?

    What do we now know about the independent assortment law?
    The ratio is 3 yellow:1 green

    • R/y.
    • F1 is the combination of the gametes.
    • Mendel's second law is that different gene pairs on different chromosome pairs assort independently in gamete formation (meiosis).

    b is just as likely to end up in a gamete with an a allele as with an A allele, and likewise for the B allele.

    We now know that this law applies to genes on different chromosomes as genes on the same chromosome generally do not assort independently, because they are held together by the chromosome itself.
  3. Different chromosomes segregate _______?

    Independent assortment of chromosomes at _______ explains ______ _____?
    Different chromosome segregate independently.

    Independent assortment of chromosomes at meiosis explains Mendel's ratio.
  4. What are the three principles of Natural selection?
    • The three principles of Natural Selection are:
    • 1. Principle of Variation- there is variation in morphology, physiology, and behavior within the same population.
    • 2. Principle of Heredity- the offspring resembles their parents more than they resemble unrelated individuals.
    • 3. Principle of Selection- some forms are more successful at surviving and reproducing than other forms in a given environment.
  5. What is heritable variation?

    Forces that increase or maintain variation, prevent population from what?
    Heritable variation is what provides the raw material for successive changes within a species and for the multiplication of a new species.

    Prevent population from divergence, but less variation causes more divergence.
  6. What are Adaptive walks?
    For five sites, there are how many possible orders?
    What is an example that Adaptive Walks were used for?
    What is the detailed definition of Adaptive Walks with regards to the Antibiotic Resistance?
    • Adaptive walks are multistep pathways of evolutionary change.
    • 5x4x3x2x1=120 possible orders.
    • Adaptive walks were used for Antibiotic Resistance.
    • Adaptive walks are the mutational steps for the 10 most probable trajectories from wild type susceptibility to the antibiotic cefotaxime to maximal resistance.
  7. What does each circle in the adaptive walk represent?

    What do the numbers indicate?

    Where is the maximal wild-type with all - and where is maximal resistance with all +++++?
    Each circle represents an allele whose identity is denoted by a string of five + or - symbols corresponding to the presence or absence of mutations.

    The numbers indicate the degree of cefotaxime resistance in ug/mL.

    The maximal wild-type is on the far right of the adaptive walk and the maximum resistance is on the far right of the walk.
  8. What are gene families?
    Gene families are groups of genes that are related in sequence and typically in biochemical function as well.
  9. What are the four ways that one can increase the gene number?
    • The four ways that one can increase the gene number are:
    • 1. Polyploids- individuals with more than two chromosome sets resulting from duplication of entire genome.
    • 2. Gene Duplication- Mis-replication of DNA during meiosis can cause segments of DNA to be duplicated. 
    • 3. Transposition- When transposable elements is transposed to another part of the genome, it may carry an additional host genetic material and insert a copy form the same part to another.
    • 4. Retrotranspositon- produces intronless gene duplication.
  10. What is melanism?
    In what organism is this found and where is it found?
    What are the two types of melanin?
    What are the two types of proteins?
    What happens in the hair-growth cycle?
    Melanism is the occurrence of a dark form within a population, such as in the rock pocket mouse.

    • The Rock Pocket mouse- Chaetodipus intermedius and it is found in the Pinacate region of Arizona on sandy colored and dark lava-rock background.
    • The two types of melanin are eumelanin (black or brown pigments) and phaeomelanin (yellow or red pigments)
    • The two types of proteins are MC1R (melanocortin 1 receptor) and agouti protein.

    In the hair growth cycle, alpha melanocyte- stimulating hormone binds to the MC1R protein, which triggers the induction of pigment-producing enzyme and the agouti protein blocks MC1R activation and inhibits the production of eumelanin.
  11. How many mutation are there that cause the protein to differ at four amino acid residues?
    There are four mutation that cause the meaning protein to differ at four amino acid residues.
  12. According to genetic studies, what did they indicate regarding the albinism in the Pachon cave fish population?

    Is albinism due to the same genetic locus?
    What is the gene called in the albino locus?
    What did further inspection of the Oca2 gene reveal?
    Genetic studies indicated that albinism in the Pachon cave fish population is due to a single recessive mutation.

    • Yes. Albinism is due to a single recessive mutation in the same genetic locus.
    • The gene is called Oca2 which is in the albino locus.

    Further inspection of the Oca2 gene revealed that the Pachon population was homozygous for a deletion that extended from an intron through mod of an exon and that the Molino population was homozygous for the deletion of a different exon.
  13. In the Dosophila Melanogaster having the wing spots due to melanin, what kind of evolution cases this?

    Can the expression of pigmentation genes differ in areas of the body that will be of different colors?
    The type of evolution that causes the spoted wings is the Regulatory sequence Evolution.

    Yes, expression of pigmentation genes can differ in areas of the body that will be different colors.
Card Set
Chapter 3 ppt