sequences from deleterious mutations. D. These regions may contain regulatory sequences that control how a gene is expressed. 3. During an immune response, B cells need to be activated by helper T cells before they become mature, antibody-producing plasma cells. If a mutation occurred such that the extracellular domain of T cell receptor becomes nonfunctional, which of the following types of cell communication will be most likely disrupted? A. paracrine signaling B. autocrine signaling C. direct signaling D. endocrine signaling
1. A mutation was introduced to the active site of the enzyme in a receptor tyrosine kinase so that it remains active in the absence of a substrate. What is the effect of this mutation on the signal transduction
pathway?
A. The phosphatase activity of the enzyme will be activated which will lead to receptor dimerization and subsequent cellular response.
B. The signal molecule will bind to the receptor and dimerization will occur but the subsequent cellular response will be inhibited.
C. The signal molecule will bind to the receptor but dimerization and subsequent cellular response will be inhibited.
D. The signal molecule will bind to the receptor which will then triggers receptor dimerization and downstream cellular response.
2. Which of the following is not an advantage of non-coding regions of DNA?
A. Some of these regions contain inactivated genes that can be reactivated upon insertion of regulatory sequences by mobile DNA elements.
B. Some of these regions protect eukaryotic DNA from degradation due to successive replications.
C. Because of their large amount in eukaryotes, they protect gene-coding sequences from deleterious
mutations.
D. These regions may contain regulatory sequences that control how a gene is expressed.
3. During an immune response, B cells need to be activated by helper T cells before they become mature, antibody-producing plasma cells. If a mutation occurred such that the extracellular domain of T cell receptor becomes nonfunctional, which of the following types of cell communication will be most likely disrupted?
A. paracrine signaling
B. autocrine signaling
C. direct signaling
D. endocrine signaling
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