In animals, embryonic lethal mutations can either in zygotic or maternal effect.  In zygotic embryo lethal mutations, the genotype of the embryo determines the phenotype of the embryo.  In contrast, mutations in genes encoding products that the mother deposits in the egg often result in maternal effects - i.e. it is the genotype of the mother, not the genotype of the embryo, that determines the phenotype of the embryo.  Diagram crosses that would allow you to determine whether an embryo lethal mutation is due to zygotic lethality or maternal effect lethality. How would you devise a screen to identify recessive mutations in Drosophila that result in maternal effect lethality?

Predict the probability (using a Punnett square) of producing an offspring affected by a single gene X-linked mutation given the genotype of the parents. Compare these crosses in two cases: where the mutant allele is “A” vs where the mutant allele is “a” (XAXA x XaY) (XAXa x XAY) (XAXa x XaY) (XaXa x XAY) (XaXa x XaY). Include gender in the phenotype.

Retinoblastoma can be seen as a familial cancer, inherited in an autosomal recessive manner (RB-/RB-), individuals heterozygous for the RB+ and RB- alleles can develop tumor as a result of… A mitotic crossover that leads to homozygosity for RB+ in some cells and RB- in other cells A meiotic mutation in the RB+ allele that leads to homozygosity for RB+ A somatic mutation in the RB- allele that leads to homozygosity for RB+ The fact that RB- is dominant to RB+

In 1952, an article in the British Medical Journalreported interesting differences in the behavior ofblood plasma obtained from several people who suffered from X-linked recessive hemophilia. Whenmixed together, the cell-free blood plasma from certain combinations of individuals could form clots inthe test tube. For example, the following table showswhether clots could form (+) or not (−) in variouscombinations of plasma from four people withhemophilia:1 and 1 − 2 and 3 +1 and 2 − 2 and 4 +1 and 3 + 3 and 3 −1 and 4 + 3 and 4 −2 and 2 − 4 and 4 −What do these data tell you about the inheritance ofhemophilia in these individuals? Do these data allowyou to exclude any models for the biochemical pathway governing blood clotting?

Males of many diploid species (like us) have X and Y sex chromosomes. They are hemizygous for most X- linked genes. Thus, males express most X-linked alleles, whether they are dominant or recessive in females. In the fruit fly Drosophila, it is common to achieve the equivalent of a test cross of X-linked genes in females by assessing the readily observed phenotypes of their male progeny. Since males do not receive X-linked genes from their father, sires of these crosses can be normal or wild-type flies. In fly genetics, it is conventional to name a gene after the mutant phenotype that enabled its discovery. Your challenge is to establish gene order and map distances between three X-linked genes in Drosophila. Each gene is represented by recessive mutant alleles that express rather distinctive phenotypes relative to their dominant wild-type alternative alleles. Flies expressing fruitless (f) are bisexual, lush (1) have a heightened responses to ethanol, and ken&barbie (kb) lack external…

Which of the following statements about calico cats is true? Select all that apply.

A blue eyed agouti hair male mouse is mated to a brown eyed yellow haired female mouse, and a test cross is performed with the F1.  Both blue eyes and yellow hair are recessive phenotypes.  What is the probability of a recovering a phenotypically blue-eyed yellow haired mouse in the F2 if: eye color  and  hair color genes  are 30 map units apart on the same autosome

In water snakes, there are three different possible skin colors: Brown, Gray & Green.   BB=Brown BG=Gray GG=Green What are the possible genotypes & phenotypes from crossing a brown & gray snake? What type of gene action is being expressed in this example?

What is the probability of Sister 3 as a carrier of the death gene?