The p53 and MDM2 proteins are involved in the DNA damage response pathway (figure 1). In the absence of DNA damage, MDM2 mediates the degradation of p53. In the presence of DNA damage, p53 is not broken
down and forms active tetramers that stimulate the expression of genes that block cell cycle progression.
Red blood cells are produced by the division and differentiation of multipotent stem cells. Researchers have
observed that mice with a partial loss-of-function mutation in the MDM2 gene have a lower concentration of red
blood cells in the blood than do mice that express the wild-type MDM2 allele.
(a) Using the model of the p53/MDM2 pathway, connect the reduction of MDM2 function in mutant mice to
the observed concentration of red blood cells.
(b) Predict how a loss-of-function mutation in the p53 gene is most likely to affect the cell cycle in response to
DNA damage. Justify your predictions.

2points what is the term for a female reproductive cell? a. egg b. chromatid c. allele d. fertilization

15 ! come and answer! a(n) is the general term for an infectious disease that has spread across a city, region, or country.

In a hypothetical breed of dogs, coat color is controlled by two genes. there are six different coat colors in this breed: black, brown, cream, gray, silver, and tan. consider the following crosses. cross 1: black females from a lineage of all black dogs are crossed with brown males from a lineage of all brown dogs. f1 males and females are all black. when f1 are intercrossed, f2 males and females are black or brown. cross 2: black females from a lineage of all black dogs are crossed with tan males from a lineage where all males are tan and all females are cream. f1 males are black, f1 females are gray. when f1 are intercrossed, f2 males and females are black, brown, gray, or tan. cross 3: silver females from a lineage where all females are silver and all males are gray are crossed with brown males from a lineage of all brown dogs. f1 males and females are all gray. when f1 are intercrossed, f2 males are black, brown, gray, or tan, f2 females are cream, gray, silver, or tan. select the correct statements regarding the mode of inheritance of the coat color genes. a) both genes are x-linked. b) both genes are autosomal. c) one of the genes modifies the expression of the other gene. d) each gene has an additive effect on the intensity of coat color. e) each gene independently specifies three colors. f) one of the genes is autosomal, and the other is x-linked.