Suppose you have a line of mice that has cytologically distinct forms of chromosome 4. The tip of the chromosome can have a knob (called 4K ) or a satellite (4S) or neither (4). You cross a 4K/4S female with a 4/4 male and find that most of the progeny are 4K/4 or 4S/4, as expected. However, you occasionally find some rare types as follows (all other chromosomes are normal): a. 4K/4K/4

A horse has 64 chromosomes and a donkey has 62 chromosomes. A cross between a female horse and a male donkey produces a mule, which is usually sterile. How many chromosomes does a mule have? Can you think of any reasons for the fact that most mules are sterile?

Assume that the Holliday junctions resolve so that there is no crossing over (that is, there is no recombination). For the maternal chromosome list all of the possible base identities at the three positions after the cell repairs any mismatches. Do the same for the paternal chromosome.”

Two different genes are located on the same chromosome in rabbits. A particular female rabbit is heterozygous for alleles of both genes, with alleles arranged as shown in the diagram to the right. Scientists know that the two genes are on the same chromosome, but do not know their exact relative positions, as indicated by the dashed line. Suppose this female mates with a male rabbit in which the same r. chromosome pair looks like this: Which of the following statements best describes the likelihood that this pair of rabbits would have offspring with a chromosome pair that looks like this: * O More likely if the two genes are not very close together on the chromosome E-i-e R- O Not likely, because the R and e alleles are not on the same chromosome in either parent O More likely if the two genes are very close together on the chromosome O Very likely, because the random assortment of chromosomes during cell division to make sperm or eggs allows for the mixing of all alleles

Diploid Number of chromosomes, Sex Chromosomes, (+/- whole) Chromosome (+/- partial) e.g. 47, XY, +14 = male with trisomy of chromosome 14 e.g. 46, XX, 1q+ = female with a partial increase to the length of the long arm of chromosome 1 (partial increases or decreases to a single chromosome still have the same diploid number) What is the notation for the following case A boy having Down syndrome

Sofia the Mini Husky (yes, she’s real) has a normal chromosome count of 34 in her diploid cells. Suppose there was an error during cell division, how many chromosomes would you find in a doubly tetrasomic cell.

The order of the genes on a plant chromosome is A, B, C, where A and B are located 10 cM apart and B and C are located 3 cM apart. What is the probability that the trihybrid ABC/abc will produce any kind of recombinant gamete?

The karyotype of a young girl who is affected with Down syndrome revealed that she has 46 chromosomes. Her phenotypically normal older brother's karyotype revealed that he has 45 chromosomes. (a) Propose an explanantion for the chromosome number in both children (b) What would you expect the chromosome number of the parents of these two children?

A prairie grass species called "little bluestem" is tetraploid. It has four complete sets of chromosomes. There are ten kinds of chromosomes; in other words, each complete set of chromosomes has a total of 10 chromosomes. A single somatic cell (e.g., a cell in a leaf) will have 40 chromosomes, 4 of each kind of chromsome, i.e., 4 of the number 1 chromsome, 4 of the number 2 chromsome, etc.  The illustration below shows prophase of meiosis 1 in chromosome number 10. In a diploid cell, there would be one tetrad (group of 4 chromatids) for each kind of chromosome.  For example, there would be one tetrad for chromosome 8, one for chromsome 9, etc.  When the tetraploid little bluestem undergoes meiosis, how many of chromosome number 10 will each sperm cell carry?

In mice, 2n = 40. If a mouse cell divides by mitosis, it will produce two daughter cells that each have  ________ chromosomes. If a mouse cell divides by meiosis, it will produce four daughter cells that each have  ________ chromosomes. Type the appropriate number to fill in each blank (e.g., 40).