Meiosis I intro

Wednesday February 20^th

1.The allele for having a widows peak (W) is dominant over the allele for having a straight hairline(w).  If someone had the following genotype, Ww, what kind of hair line do they have?

They would have a widows peak.  What I gave you was a Genotype (which is the set of alleles for a trait)  Since there is a dominant allele (W) then it doesn't matter what the second allele is, because it is dominant, that is what is expressed.  When you told me that they would have a widows peak, you were telling me there Phenotype.  These were all new terms that we discussed yesterday.  I then had you look at your magnet boards at homologous chromosomes and you told me the genotypes of different genes.  This then led to the second question.

2. Which allele will they be more likely to pass on to their offspring?

there will be an equal chance of passing either the Dominant (W) or the recessive (w) on to their offspring.  These alleles are randomly segregated during meiosis. 

3.  During what process will this be determined?

Meiosis.   We will continue to use these magnet boards to see how the alleles get distributed among gametes. 

KQOD.  Which statement best explains why large changes in pH can affect the functions of plant enzymes?

Large changes in pH increase the rate of cellular chemical reactions

B.  Large changes in pH provide the energy necessary to activate an enzyme

C.  Large changes in pH can denature an enzyme causing a change in its shape

D.  Large changes in pH cn cause an enzye to react with a different substrate

This question was not only about the function of enzymes, but how pH and temperature affect enzyme activity.  Many of you picked A or B - these both describe the FUNCTION of enzymes - but the question was about how large changes in pH will affect the enzyme.  Large changes in pH or temperature will change the shape of an enzyme.  Recall that we learned enzymes are proteins and they are dependent on the shape.

After these we started into the first part of meiosis.  Using our magnet boards we put the cell at least into prophase 1 and discussed all the different factors that contribute to genetic diversity at this point.