Background for Genetics Problems

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Background for Genetics Problems:
In Mendel’s famous work with peas, he discovered that a variety of plant traits could be explained through inheritance of
Information carried on discrete particles that were passed from parent to offspring. The information and particles were later described as genes (or, alleles) on chromosomes.
Through his work and meticulous attention to details, Mendel was able to determine that the allele resulting in dwarf pea plants (dw) was recessive to the wildtype variety (+, tall) and that the constricted seedpod shape allele (cs) was recessive to a wildtype allele (+, inflated). Mendel’s extensive work with various crosses demonstrated that these characters assorted independently (meaning, they are not linked on the same chromosome).
Part 1: DNA and Chromosomes
Use a heterozygous pea plant (+/dw +/cs) to draw representations of cell nuclei at various stages in cell cycle using the table on the following page. In each drawing, label:
+,dw, and cs alleles
Homologous chromosomes
Sister chromatids
Centromeres
For this problem, you may assume that there is a long sequence of bases for each gene and the alleles for each gene differ as follows. Use these in the construction of your answer for the middle column of the table.
+ allele: 3’ —- ATAAGC —- 5’ + allele: 3’ —- CTT —- 5’
dw allele: 3’ —-TTTACG —- 5’cs allele: 3’ —-CGA —- 5’
Mitosis:
Life Cycle Phase
Chromosome representation
Double-Stranded DNA molecule (Base –pair sequences with 3’ and 5’ ends labeled)
Summary
Heterozygous pea plant cell at G1
*this cell is your
“starting point”
For the rest of the drawings
Number of cells =
n=
Ploidy=
DNA replicated or unreplicated state?
G2
Number of Cells=
n=
Ploidy=
DNA replicated or unreplicated State?
Metaphase of Mitosis
Number of Cells=
n=
Ploidy=
DNA replicated or unreplicated State
Daughter Cells (products of mitosis)
Number of Cells=
n=…