Describe point mutations, nonsense mutations, and frameshift mutations. Discuss the likely effect of each type of mutation on a protein being built
What will be an ideal response?
A point mutation occurs when one nucleotide is substituted for another. Point mutations sometimes change the sequence of amino acids in a protein. For example, a mutation from AAC to AAG would replace asparagine with lysine. Not all point mutations affect amino acids, however: A mutation from GCA to GCC would have no effect because both codons code for alanine. Does a change in a single amino acid really matter? Sometimes it does and sometimes it doesn't. The sickle cell hemoglobin allele differs from normal hemoglobin by only one amino acid. In addition, for proteins that function as enzymes, the lock-and-key fit of enzyme to substrate can be disrupted by a single amino acid change. A nonsense mutation creates a stop codon in the middle of a protein-coding sequence. Nonsense mutations result in the production of shorter, often nonfunctional proteins. The insertion and deletion of nucleotides can result in a frameshift mutation. In a frameshift mutation, the triplet codons that are "read" and translated are shifted, completely altering the amino acid sequence in the protein being assembled. Frameshift mutations usually have significant disruptive effects on proteins.
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From this cross section of the Grand Canyon, what is the boundary between the various Precambrian rocks and the Paleozoic sedimentary units?
A. It generally is an unconformity and represents more time in the right part of the diagram than in the left part of the diagram. B. It is a depositional contact, probably representing only a short period of geologic time. C. It is an angular unconformity in most places and a nonconformity where it overlies granite. D. All of these.
The development of a mid-latitude cyclone, according to the Norwegian model, begins along the?
a. ?conveyor belt. b. ?wave cyclone. c. ?cyclone. d. ?incipient cyclone. e. ?anticyclone.
______ is the idea that continents move freely over Earth's surface, changing their positions relative to one another.
What will be an ideal response?
Answer the following statement(s) true (T) or false (F)
1. A top-down approach to solving environmental problems can help facilitate bottom-up approaches by building infrastructure to support virtual environmentalism. 2. Dialogic democracy suggests that the power of individuals at the “top” is independent of the power held by those at the “bottom”. 3. Participatory development helps ensure that the local community is supportive of and invested in projects that link top-down and bottom-up approaches to environmental challenges. 4. Environmental movement should be strictly bottom-up because top- down policies rarely do any good to the environment.