A number of mutations have been described in G proteins that have profound effects on their activity. For example, some mutations greatly increase the affinity of the G protein for GDP making it very difficult to be exchanged for GTP
Other mutations prevent the hydrolysis of
GTP to GDP.
Which of the following scenarios would still result in a proliferation signal via the kinase
cascade in the absence of ligand binding to its receptor tyrosine kinase?
A. A continuously active receptor and an
inactive Map kinase pathway
B. A Ras molecule that has no GTPase
activity
C. A continuously inactive MAP kinase
pathway and an inactive Ras
D. A continuously active Ras and an inactive
MAP kinase pathway
E. A continuously activated receptor in the
absence of ligand
B
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T cell receptors can discriminate between self (MHC markers) and nonself (____)
Fill in the blank(s) with correct word
The sedimentary rock known as ________ stores carbon deposited by the shells of ocean animals
Fill in the blank(s) with correct word
Apical meristems of dicots are at the tips of stems. Apical meristems of grasses are at ground level or slightly below, concealed by the leaves. The leaves also have an intercalary meristem at their bases
What does this mean when considering care of a lawn or soccer field? A) If you mow right at ground level, the leaves can keep growing with no problem. B) Grass mowed two inches above ground level grows at a slower rate compared to grass mowed three inches above the ground level. C) If you mow two inches above ground level, most apical meristems will be cut down. D) If you mow two inches above ground level, both the apical and intercalary meristems can keep producing new cells.
What is the term for organisms in which internally-fertilized eggs are laid to develop and hatch outside the mother's body?
A. Viviparous B. Marsupial C. Ovoviviparous D. Placental E. Oviparous