GENETICS - BIOL 7        EXAM IV - December 13,  2005    NAME:

DO NOT USE ANY OTHER PAPER AT ANY TIME WITHOUT INSTRUCTOR PERMISSION

Part I: [42 points]  Choose the one BEST answer.  Circle its letter. Read each question and all 5 choices carefully because more than one answer might seem correct at first glance.  1  point each

1.  Which of the following is important for regulation of gene expression?
          a.  transcription of mRNA
          b.  translation of mRNA
          c.  degradation of mRNA
          d.  transport of mRNA
          e.  all of the above

2.  The norm of reaction is a description of a series of different
          a.  genotypes within an environment
          b.  phenotypes produced by a same genotype, as the environment is varied
          c.  phenotypes compared with different environments
          d.  genotypes produced by the same phenotype, as the environment is varied
     e.  mating rates within a population

3.  A partial diploid of genotype Is P+ O+ Z+/ I+ P+ O+ Z- will express
          a.  inducible repressor
          b.  inducible β- glactosidase
          c.  constitutive β- glactosidase
          d.  no β- glactosidase
          e.  constitutive lactose

4.  If f (AA) = 0.09, f (Aa) = 0.42, f (aa) = 0.49 then the system
          a.  is in Hardy-Weinberg equilibrium
          b.  is evolving
          c.  is make believe because f(aa) > f(AA) is not plausible
          d.  demonstrates migration
          e.  will become f(AA) = .25, f(Aa) = .5, f(aa) = .25 within a few generations

5.  Trans-acting factors
          a.  are regions of DNA that move
          b.  are regulated independently of the genes they regulate
          c.  are always polypeptides
          d.  in prokaryotes, are encoded by genes coordinately regulated in an operon
          e.  are never regulated

6.  Are the conditions for Hardy-Weinberg equilibrium ever met in reality?
          a.  no, because no population is infinite in size
          b.  no, because nonrandom mating always occurs
          c.  yes, because migration rarely occurs
          d.  yes, because mutation rarely occurs
          e.  never perfectly satisfied, but often can be approximated, at least for some traits or loci

7.  A genetic marker
          a.  is used only for mapping analysis
          b.  is any gene
          c.  is any DNA sequence which can be recognized
          d.  is any gene which results in a recognizable phenotype
          e.  can be found only in eukaryotes

8.  A merozygote
          a.  is haploid at some loci and diploid at others
          b.  is a special genetic form of E. coli
          c.  must be prokaryotic
          d.  is always the result of conjugation
          e.  occurs only as a result of conjugation
          f.  all of the above

9.  Which of the following formulas lets you predict the genotypic frequency of the next generation?
          a.  p + q = 1
          b.  X2 = sum [(o - e)2 / e]
          c.  p2 + 2pq + q2 = 1
          d.  Pnx = [(n!)/(x!  (n-x)!)]  px  q(n-x)
          e.  none of the above - one can only make these predicitons when a population is in equilibrium

10.  Is DNA sequence alone sufficient to regulate gene activity?
          a.  YES, because promoters are specific DNA sequences
          b.  YES, because trans-acting factors bind specific DNA sequences
                        c.  NO; we know this because all cells in an organism contain the same DNA, but different products are made in different cell types
          d.  NO, because histones bind DNA randomly
          e.  In some organisms, YES; in some, NO

11.  In Hfr x F-  crosses
          a.  virtually none of the F-  parents are converted into F+
          b.  virtually none of the F-  parents are converted into Hfr
          c.  almost all of the F-  parents are converted into F+
          d.  almost all of the F-  parents are converted into Hfr
          e.  a and b
          f.  a and d
          g.  b and c

12.  If f(AA) = 0.36 and f(Aa) = 0.48,  the allelic f(A) =
          a.  0.84
          b.  0.42
          c.  0.60
          d.  0.06
          e.  0.16

13.  During (or as a result of) mating between Hfr and F- cells, the Hfr donor
          a.  becomes F’
          b.  becomes F+
          c.  becomes F-
          d.  loses part of the chromosome
          e.  remains Hfr
          
14.    The Hardy-Weinberg formula can be used
          a.  to estimate allele frequency if phenotype frequency is known
          b.  to estimate phenotype frequency if allele frequency is known
          c.  a and b are true under all conditions
          d.  a and b are true only for populations in equilibrium
          e.  all of the above

15.  A trans-acting factor
          a. is a DNA sequence
          b. binds a DNA sequence
          c. is a histone
          d. is an operator gene
          e. is inactive when in "cis" conformation

16.  In eukaryotes
          a.  translation occurs in the nucleus
          b.  introns are removed from mRNA
          c.  3' polyadenylation occurs only in the nucleus
          d.  splicing evolved for the first time
          e.  introns and exons are removed from all primary transcripts

17.  One consequence of the Hardy-Weinberg Law is that
          a.  genetic variability is stabily maintained in a population
          b.  dominant traits increase in frequency from one generation to the next
          c.  allele frequencies change constantly in a population
          d.  knowing the frequency of one genotype will tell you nothing of the other genotypes
          e.  heritability

18.  A merozygote is formed in E.  coli when
          a.  the F factor and several adjacent genes are excised from the chromosome, and form a plasmid which is transferred to an F- strain
          b.  the F factor excises, causing an Hfr strain to revert to F-
          c.  the F factor inserts causing an F+ strain to become F-
          d.  the F factor inserts causing an F-  strain to become F+
          e.  the F factor inserts causing an F+ strain to become Hfr, which then conjugate with an F- strain

19.  F’is
          a.  always integrated at the same place to give back the original chromosome
          b.  reverted back to an Hfr strain less frequently than an F+ strain
          c.  a cytoplasmic element that carries a part of the bacterial chromosome
           d.  a and b
          e.  all of the above

20.  The separation technique which commonly uses materials such as polyacrylamide, starch, or agarose is
          a.  gel electrophoresis  
          b.  chromatography
          c.  centrifugation
           d.  a and b
          e.  all of the above

21.  Since the F factor can exist either separate from the chromosome or incorporated into it, it is a(n)
          a.  free body
          b.  autosome
          c.  episome
          d.  chromatid
          e.  plasmid

22.  Which of the following strains would not grow on minimal medium, but would grow on minimal medium supplemented with threonine, leucine, and thiamine?
          a.  met- bio- thr+ leu+ thi-
          b.  met+ bio+ thr- leu- thi-
          c.  met+ bio+ thr+ leu+ thi+
          d.  a and b
          e.  all of the above

23.  In the process of gel electrophoresis, DNA fragments can be separated from each other based on
          a.  the fact that some of the DNA will be single stranded while others will be double stranded
          b.  the length of each fragment
          c.  the fact that some fragments are negatively charged while others are positively charged
          d.  the ratio of thymine to adenine base pairs compared to cytosine to guanine base pairs
          e.  the secondary structure and supercoiling of the different fragments

24.  The null hypothesis assumes that
          a.  the predicted values take into account information which is already known
          b.  chance results in a normal distribution
          c.  any difference between expected and observed results is attributed to chance
          d.  a and b
          e.  all of the above

25.  The entirety of an individual's genotype, including known and unknown genes, is the
          a.  genetic milieu
          b.  complementation
          c.  pleiotropy
          d.  familiality
          e.  quantitative variation

26.  If an amino acid sequence is known, one can infer the:
          a. DNA coding sequence
          b. RNA coding sequence
          c. polypeptide function
          d. a and b
          e. none of the above

27.  Conjugation in E. coli requires
          a.  the F plasmid to be autonomous in the cytoplasm
          b.  a group of F genes to be present in the donor but not the recipient
          c.  an autonomous origin of replication
          d.  integration of the F plasmid ito the host chromosome
          e.  the F (fertility) gene product

28.  An example of a cis-acting element is
          a.  promoter
          b.  RNA polymerase
          c.  lac repressor
          d.  allolactose
          e.  the gene for the lac repressor

29.  If, over time, the frequency of the B allele in a population changes to become 0.7, the b allele would
          a.  not change in frequency
          b.  eventually disappear
          c.  change in frequency to 0.5
          d.  change in frequency to 0.3
          e.  change in frequency to 0.7

30.  When experimental data do not fit the predicted result, and p<< 0.05,
          a.  the hypothesis is proved false
          b.  the hypothesis is proved true
          c.  the hypothesis may be true, but the most likely interpretation is that it needs revision
          d.  the experiment was done improperly, and must be repeated
          e.  the analysis was incorrect and must be recalculated

31.  It is most effective to study a population with two genotypes in an environment in which
          a.  the difference between genotypes is small
          b.  the difference between norms of reaction is small
          c.  the difference between phenotypes is small    
          d.  the two phenotypes are very different from each other
          e.  the difference in genotype has no effect regarding norms of reaction

32.  A factor that can influence the norm of reaction of a plant is
          a.  rainfall
          b.  carbon monoxide levels
          c.  elevation
          d.  light
          e.  all of the above

33.   Single-stranded DNA extracted from human cells is added to single-stranded DNA from chimpanzee cells. The two different DNA strands bind tightly to each other, indicating much similarity in base sequences. This technique is called
          a.  DNA hybridization
          b.  DNA sequencing
          c.  DNA electrophoresis
          d.  DNA transcription
          e.  other:                                          

34. Which of the following is NOT a requirement for Hardy-Weinberg equilibrium?
          a.  random mating
          b.  mutation
          c.  large population size
          d.  no migration
          e.  no natural selection

35.  Genetic equilibrium means
          a. it is another term for being homozygous, breeding true
          b. allele frequency in a population does not change from one generation to the next
          c. phenotype frequency in a population does not change from one generation to the next
          d. gene frequency in a population does not change from one generation to the next
           e. a population is very large and mates randomly

36. Resistance to an antibiotic can be transferred from one bacterium to another by
          a.  transformation via a plasmid
          b.  gel electrophoresis
          c.  an antibiotic
          d.  an enzyme
          e.  evolution

37.  The Hardy-Weinberg Law states that
          a.  in a large, randomly mating population, allele frequencies do not change
          b.  in a large, randomly mating population, allele frequencies change
          c.  in a small, randomly mating population, allele frequencies do not change
          d.  in a small, randomly mating population, allele frequencies change
          e.  a and d
          f.  b and c

38. If two organisms appear to be the same, except that one can tolerate higher temperatures than the other, what conditions should be used to study the gene(s) involved in temperature tolerance?
          a.  cool temperatures where both organisms thrive; use some other stressful condition (not temperature)
          b.  warm temperatures where both organisms thrive
          c.  very warm temperatures where one organism thrives but the other barely survives
          d.  hot temperatures where one organism survives but the other dies
          e.  extremely hot temperatures which kill both organisms, but one survives longer than the other

39.    If 36% of the population is heterozygotic for a certain gene, what percentage of the population will show the recessive phenotype in the next generation?
          a.  4%
          b.  8%
          c.  16%
          d.  34%
          e.  not enough information

40 -42.  Explain.


Part II:  [66 points] Answer each question completely and clearly.  Show your work for possible partial credit.  Make sure your answer is clearly stated, and easy to find.  Make sure you have answered all the parts of the question.  10 points each

1.  For the following populations (each is independent) give the values of p & q, and state whether the population is in Hardy-Weinberg equilibrium [where p = freq(A); q = freq(a) alleles, respectively] :

population          AA          Aa          aa                      p              q             equilibrium? [yes/no - show why]

1                    0.0          1.0          0.0                                                            
2                    1/3          1/3           1/3                                                            
3                    .36          .48           .16                                                            
4                    .04          .32           .64                                                            
5                    .1          .5           .4                                                            


2.  Use the following key to indicate the phenotype expected from the indicated strains of E. coli.

               no lactose              lactose    
a.                     +                      +    
b.                     -                      +
c.                     -                      -
d.                     +                      -
e. none of the above OR not enough information given    if (e): bonus for correct answer: write it next to the genotype

     

β-galactosidase	permease		explain if necessary
		I+ Oc Z+ Y+
		I- O+ Z+ Y+
		I+ O+ Z- Y+
		Is O+ Z+ Y+
		Is O+ Z- Y+
		I+ O+ Z+ Y+
		F' Is Oc X+ Y- / I- O+ Z+ Y+
		F' I- O+ Z+ Y- / I+ O+ Z- Y+
		F' I- O+ Z+ Y- / I+ Oc Z- Y+
		F' I+O+ Z- Y+/ I- Oc Z+ Y-

3.  Map the chromosome from the following interrupted Hfr conjugation data.   Markers are shown in the order they were donated.  Explain what a “strain” is; how were these strains used to generate the map (in other words - show your work)

strain 1              A    Q    R    J
strain 2        V    S    J    R
strain 3        D    B    E    W
strain 4        S    V    M    D
strain 5        W    K    A    Q
strain 6        K    W    E    B

4.  Referring to the graph:

a. Explain how this information could be used to help
   devise conditions for a study of this system

b. Indicate what conditions you would use - and why
   (this answer may be merged with part (a)

c. Is this system likely to be an experimental
   organism, human, or could be either?  Explain.


5.  A geneticist's preliminary results, and the results of a second, larger study are shown below.  In both cases, known doubly heterozygous organisms were test crossed.  Analyze each experiment separately (show your work; indicate p value for each experiment), and then draw a conclusion about the MOST LIKELY map of the two genes tested.  If the conclusions  differ, explain which you think is correct, and why you think it is more likely to be valid.  What is the most likely final explanation of these data?

             Experiment A     Experiment B
HG                    29              290
Hg                     21              210
hg                      27              270
hG                     23              230

6.  [16 points]          a.  Describe how an Hfr strain is established.  How does this help explain that Hfr strains differ from each other?

          b.  How can the Hfr system be used to map an entire genome?  Is it necessary to use different Hfr strains?   Explain your answer - diagrams may help (but are not sufficient without explanation of what they show).  This answer must go beyond the demonstration in problem # 3.

          c.  What is F+?  Are there different strains?  If so, how do they differ?  How can F+ be used in the lab?

          d.  What is F' ?  How is it formed?  Are there different strains?  If so, how do they differ?  How can F' be used in the laboratory?