Cell Biology: Nucleus 14367.A 55-year-old man with difficulty urinating, blood in the urine, burn-
ing during urination and accelerating prostate-specific antigen (PSA) has a
radical prostatectomy. The diagnosis is prostate carcinoma with a Gleason
score of 7. Rb, p53, and bcl-2 genes are involved in the development of
prostate carcinoma. Which of the following mechanisms may be involved
in the loss of cell cycle control that occurs in prostate carcinoma?
a. Increased CdkI activity
b. Decreased transcription of G 1 /S cyclin
c. Decreased expression of bcl-2
d. Increased transcription of gene regulatory proteins such as E2F
e. Dephosphorylation of Rb
68.Decreased recombination is associated with the production of aneu-
ploid sperm in humans. Meiotic crossover occurs in which of the following
stages?
a. Leptotene
b. Zygotene
c. Pachytene
d. Diplotene
e. Diakinesis
69.An obese 18-year-old man presents with small firm testes, a small
penis, little axillary and facial hair, azoospermia, gynecomastia, and elevated
levels of plasma gonadotropins. He has had difficulty in social adjustment
throughout high school, but this has worsened and he has been referred for
genetic and endocrine screening. The karyotype from peripheral blood
leukocytes would most likely show how many Barr body/bodies?
a. None
b. One
c. Two
d. Three
e. Four