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COLORADO SCHOOL OF MINES Logan Weinman I Core Supplemental Instruction Facilitator | Biology I

April13,2017 BiologyI CSIWorksheet11

1. Review the similarities and differences between mitosis and meiosis.

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COLORADO SCHOOL OF MINES Logan Weinman I Core Supplemental Instruction Facilitator | Biology I

2. Nondisjunction has occurred in a father’s sperm cell during meiosis I. Draw out the daughter cells and list the possible zygote genotypes. Only worry about the X and Y chromosome for this example.

3. Nondisjunction has occurred in a father’s sperm cell during meiosis II. Draw out the daughter cells and list

the possible zygote genotypes. Only worry about the X and Y chromosome for this example.

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COLORADO SCHOOL OF MINES Logan Weinman I Core Supplemental Instruction Facilitator | Biology I

4. In fruit flies, curved wings (cr) are recessive to straight wings (cr+), and ebony (b) body is recessive to

gray body (b+). A cross was made between true-breeding flies with curved wings and gray bodies (P1) to flies with straight wings and ebony bodies (P2). The F1 offspring were then mated to flies with curved wings and ebony bodies to produce an F2 generation.

A. Draw the P1 and P2 gametes, labeling the alleles for both genes assuming the traits are on 2 different

chromosomes. Use a solid line to represent P1 chromosomes and a dotted line to represent P2

chromosomes.

B. Illustrate the F1 offspring’s chromosomes in G1, metaphase I and metaphase II of meiosis using the templates below. Do not show crossing over or spindle fibers in your illustration.

P1#Gamete# P2#Gamete# F1#Offspring#in#G1#

F1#at#Meiosis#I# F1#at#Meiosis#II#

cr#

b+#

cr+#

b#

cr#

b+#

cr+#

b#

cr+#

b#

cr+#

b#

cr#

b+#

cr#

b+#

cr+#

b#

cr+#

b#

cr#

b+#

cr#

b+#

Homologous##Chromosomes#

Sister##Chromosomes#

Centromere#

Telomere#

P1#Gamete# P2#Gamete# F1#Offspring#in#G1#

F1#at#Meiosis#I# F1#at#Meiosis#II#

cr#

b+#

cr+#

b#

cr#

b+#

cr+#

b#

cr+#

b#

cr+#

b#

cr#

b+#

cr#

b+#

cr+#

b#

cr+#

b#

cr#

b+#

cr#

b+#

Homologous##Chromosomes#

Sister##Chromosomes#

Centromere#

Telomere#

P1#Gamete# P2#Gamete# F1#Offspring#in#G1#

F1#at#Meiosis#I# F1#at#Meiosis#II#

cr#

b+#

cr+#

b#

cr#

b+#

cr+#

b#

cr+#

b#

cr+#

b#

cr#

b+#

cr#

b+#

cr+#

b#

cr+#

b#

cr#

b+#

cr#

b+#

Homologous##Chromosomes#

Sister##Chromosomes#

Centromere#

Telomere#

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COLORADO SCHOOL OF MINES Logan Weinman I Core Supplemental Instruction Facilitator | Biology I

C. In the F1 meiosis I or II drawing label an example of the following features: homologous chromosomes, sister chromatids, centromere and telomeres.

D. Name the phenotypes that will be seen if you take an F1 female and mate it to a male with the following

genotype: crcrbb. What are the predicted phenotypic ratios of the offspring?

Curved wings ebony body, straight wings ebony body, straight wings gray body, curved wings gray body 1:1:1:1 ratio

E. (+2) Suppose the following the following data were obtained for the offspring of the cross described in

D. What do these data indicate about the location of the genes for these two traits?

28 curved wings, ebony body 177 straight wings, ebony body 22 straight wings, gray body 173 curved wings, gray body

The data indicate that the genes for wing shape and body color are on the same chromosome, with a recombinant frequency of 12.5%, which tells us that the genes are 12.5 cM apart.

5. 20 centromeres are observed in a diploid cell during prophase of meiosis I. How many pairs of chromosomes does the organism contain? The cell contains 10 pairs of chromosomes.

6. Complete a Punnett square for the following cross: AaBb x aaBb (where the “A” locus and the “B” locus are on separate chromosomes). A is representative of wavy hair; a, straight hair. B is representative of brown hair; b, black hair. How many have each phenotype?

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COLORADO SCHOOL OF MINES Logan Weinman I Core Supplemental Instruction Facilitator | Biology I

7. What three general processes are involved in producing genetic diversity? Crossing-over during prophase I, independent assortment during metaphase I, fertilization of a random egg by a random sperm.

8. What is the major aspect of a cell’s DNA that signals the cell to stop dividing or never divide again.

Once the telomere of a cell is significantly shortened the cell will stop dividing. Telomerase will help slow down this process by adding back to the lagging strand. However, once the telomere is too short the cell will stop dividing because of the extensive amount of missing genetic code.

9. Draw two lines indicating a replication bubble in DNA, assign the 5’ à 3’ polarity of each strand, and label the direction of DNA synthesis for each strand at both ends of the bubble. Indicate which of the four newly synthesized strands – two at each end of the bubble – are the leading and lagging strands.

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COLORADO SCHOOL OF MINES Logan Weinman I Core Supplemental Instruction Facilitator | Biology I

10. In the inheritance of the coat color in rodents, allele A specifies agouti (Black pigment at the tips of the hair that changes to brown towards the root), which is dominant over black, a. Allele C permits full deposition of color pigment, but two recessive alleles cc, results in a albino rodent. Predict the phenotypes of the coat color and their proportions resulting from the following cross:

a. AaCc x Aacc b. AaCc x AaCc