These two frog species separate by reduced hybrid viability. In reduced hybrid viability gene of different parent species may interact and impair the hybrid's development while in a reduced hybrid fertility a viable individual is sterile often due to the inability to produce normal gametes in meiosis. Hybrid breakdown; the first generation are viable and fertile, but when they mate the offspring are feeble and sterile.
Answer:
The correct answer is option d.
Explanation:
An illustration of epigenetic change is a microbe, which can stimulate modifications in the host DNA, causing suppression of defenses or weakening of individual cells. Epigenetic changes modify the physical composition of DNA.
One of the examples of epigenetic change is DNA methylation. DNA methylation refers to the supplementation of methyl group, which inhibits some of the genes from getting expressed. One of the conditions of DNA methylation is cancer.
In the majority of cancer, the tumor cells go through global hypomethylation. The tumor suppressed genes seem to turn highly methylated in the conditions of cancer.
<span>Neutral mutations are neither harmful nor beneficial.
Therefore, they are invisible to natural selection. (Since they neither improve nor worsen one individual's chances of survival and reproduction over another.)
However neutral mutations can still spread into the population by just random replications and matings. This is called genetic drift.
In other words, they are 'silent'. They are mutations that exist and propagate in populations, but seem to have no effect at all.
The reason they can become important to evolution is that a day can come when they *do* have an effect. In other words, even though an individual mutation may have no immediate effect on survival or reproduction, a *combination* of neutral mutations may provide some new benefit or harm ... at which point natural selection *will* act on that combination.
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Answer:
C) Through genomic imprinting, methylation regulates expression of the paternal copy of the gene in the brain.
Explanation:
The pattern of gene expression wherein either paternal or maternal gene is expressed in specific cells while the other one is prevented from expression is known as genomic imprinting.
In the given example, the maternal copy of the gene on chromosome 15 is expressed in brain cells while its paternal copy is not expressed in these cells. Hence, the pattern of expression of this gene is regulated through genome imprinting. One of the mechanism is methylation of cytidine residues of CpG islands of the DNA that are more frequently present within promoters of the genes.
When the cytidine residues of these sequences are methylated into 5-methylcytidine, the transcription factors do not bind to these promoters preventing the expression of these genes.
Hence, methylation of cytidine residue in CpG islands of the promoters of the gene present on chromosome 15 could have silenced its expression in brain cells.
Answer:
Hi there!
The correct answer is igneous rock.
Igneous rocks they are most likely to experience brittle deformation is termed as breaking of rocks.
