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Unit 3, Chapter 14
Other Forms of Inheritance
1. Observe the photo on p. 368. Based on your understanding of
genetics so far, what could cause the varied colors of these wild
horses?
2. Study Figure 14.1. In your own words, explain what you are
looking at, based on mRNA processing prior to translation.
3. Do mutations provide an advantage or disadvantage to an
organism? Explain.
4. Can the same allele produce the same effect in all organisms of
the same species? Of the same genetic pool of species? Explain.
5. Can the environment affect the expression of genes? Explain.
Then, explain the photo below of two snowshoe hares.
6. Explain the basic operon model.
7. Look at the lac operon model below. Explain what happens in
the presence of lactose. In the absence of lactose.
Is this an inducer model? Or repressor?
8. Now look at the tryptophan operon.
A
B
In which model is tryptophan present? A or B Absent? A or B
9. In what organisms do these operons work?
10. Are there the same gene regulatory mechanisms in eukaryotic
cells as well? Explain.
11. What part of the ATP molecule is transferred to other
molecules, particularly proteins, in biochemical reactions?
12. Briefly summarize the four patterns of inheritance as discussed
in Table 14.1 on p. 373.
13. On what type of inheritance are they based?
14. Look at Figure 14.4. Answer the question asked.
15. From whom does mitochondrial DNA (mtDNA) come? Who
inherits it?
16. After reading about mtDNA, study the diagram below and
explain how this fulfills the needs of the eukaryotic cell:
17. What happens to the mitochondria in the sperm during the
fertilization event?
18. So, how do we determine our human origins?
19. Read the Biological Challenges on p. 376. What serious
consequences can happen if mutations affect mitochondria?
20. What is the mutation rate of mtDNA compared to nuclear DNA?
21. Be able to discuss genomic imprinting and its effects when
inherited from mom or dad. (To help you understand this
phenomenon, study Figure 14.9)
22. What is methylation? How does it contribute to our
understanding of genomic imprinting and X-inactivation?
23. Remember from the chemistry section, that the methyl group is
the only group that is insoluble in water. How does this enable the
processes mentioned in #22?
24. Suppose you have a regulatory pathway (See Figure 3): A turns
off B , B turns off C and C turns on or Activates X. “X" is an arbitrary
developmental process. When A is on this leaves B off, which in
turn lets C come on therefore X is ON. Therefore the net effect of A
is to turn on X. If there was a loss of function mutation in A such
that A is off this allows B to be on which in turn turns off C which
can’t activate X leading to a phenotype. If the only function of
gene A is to turn off gene B then a suppressor of mutant A would
include loss of function mutations in B as this mutation bypasses the
need for gene A. Other potential suppressors include gain of
function activating mutations in C or X. This type of suppressor
approach is what geneticists call suppression by epistasis.
Based on this explanation, how would you explain the following
diagram of the breed Puli which is traditionally white? (Two black
sire and dam mated to produce these three offspring.)
25. What is the minimal number of genes involved in epistasis?
26. What is the main contributing factor to genetic-anticipation
disorders?
27. Describe this connection.
28. Who was Barbara McClintock and what was her contribution to
the study of “jumping genes?”
28. What effect can this movement have on gene expression?
29. Using your Webresources by visiting BSCSblue.com, view the
animated explanation of how jumping genes produce variable kernel
color in Zea mays.