The question is incomplete. The complete question is as follows:
Which of the following mutations is most likely to cause a phenotypic change?
A) a duplication of all or most introns
B) a large inversion whose ends are each in intergenic regions
C) a nucleotide substitution in an exon coding for a transmembrane domain
D) a single nucleotide deletion in an exon coding for an active site
E) a frameshift mutation one codon away from the 3' end of the nontemplate strand
Answer: D) a single nucleotide deletion in an exon coding for an active site
Explanation:
Deletion or insertion of a single nucleotide in an axon coding for an active site is called frameshift mutation.
The sequence of codons is read during translation, in order to synthesize a amino acids chain and form a protein from the nucleotide sequence. Frameshift mutations occur when the usual codon sequence is broken by the deletion or addition of one or more nucleotides. For example, if only one nucleotide is removed from the axon sequence during the RNA splicing process, then there will be a disrupted reading frame for all codons before and after the mutation. This may result in several incorrect amino acids being introduced into the protein. Disruption in protein sequence will cause phenotypic change.
Hence, the correct option is D) a single nucleotide deletion in an exon coding for an active site
.
mRNA
Messenger RNA is used to copy and encode genetic information from DNA base pairs by forming complementary strand of RNA molecule from the nucleus of the cell to the cytoplasm.
tRNA
Transfer RNA reads sequence of nucleotide from messenger RNA and translate them into proteins or amino acids during proten synthesis.
Transcription
This is the first step in gene expression where information from DNA is copied into a complementary strand of RNA molecule using RNA polymerase enzyme.
Translation
Messenger RNA made from the process of transcription travels to the ribosomes in the cytoplasm where proteins are produced using transfer RNA to copy the information.
The use of DNA to make proteins.
Through gene expression (central dogma of biology), the DNA molecule carries information, a gene code, in form of base pairing sequences that are transcribed to RNA and further translated to functional proteins or amino acids.
Answer:
Mitosis occurs in somatic cells; this means that it takes place in all types of cells that are not involved in the production of gametes. Prior to each mitotic division, a copy of every chromosome is created; thus, following division, a complete set of chromosomes is found in the nucleus of each new cell. Indeed, apart from random mutations, each successive duplicate cell will have the same genetic composition as its parent, due to the inheritance of the same chromosome set and similar biological environment. This works well for replacing damaged tissue or for growth and expansion from an embryonic state. Because the genes contained in the duplicate chromosomes are transferred to each successive cellular generation, all mitotic progeny are genetically similar. However, there are exceptions. For example, there are genetic variations that arise in clonal species, such as bacteria, due to spontaneous mutations during mitotic division. Furthermore, chromosomes are sometimes replicated multiple times without any accompanying cell division. This occurs in the cells of Drosophila larvae salivary glands, for example, where there is a high metabolic demand. The chromosomes there are called polytene chromosomes, and they are extremely large compared to chromosomes in other Drosophila cells. These chromosomes replicate by undergoing the initial phases of mitosis without any cytokinesis (Figure 2). Therefore, the same cell contains thick arrangements of duplicate chromosomes side by side, which look like strands of very thick rope. Scientists believe that these chromosomes are hyper-replicated to allow for the rapid and copious production of certain proteins that help larval growth and metamorphosis
Explanation:
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