Answer.
Actually all of these are involved.
Explanation:
Transcription is the process where genetic material or DNA is copied into RNA by the enzyme RNA polymerase. The transcription unit is made up of a promoter, a protein-coding sequence an attenuation sequence, a termination sequence. The rotein coding sequence contain the structural genes which Consist of two strands which is known as template strand and coding strand. Attenuator sequence can be as a result of stop signal which can also lead to transcription.
Answer:
a prezygotic barrier
Explanation:
Both wild tigers and lions are said to be reproductively isolated.
Reproductive isolation is defined as the existence of barrier between organisms of different species such that they cannot reproduce.
The mechanisms of reproductive isolation varies. While some act to prevent the formation of zygotes (in case of mating) between organisms of different species, some ensures that the resulting zygotes are invalid.
Reproductive isolation mechanisms that act to prevent fertilization and formation of zygotes are referred to as prezygotic mechanisms while those that ensure that invalid zygotes result (in case of successful fertilization) are referred to post zygotic mechanisms.
<em>The natural differences in the ranges of wild tigers and lions ensure that both animals do not mate with each other, let alone results in zygote. This is a form of pre-zygotic reproductive isolation mechanism.</em>
Answer:
<u>the bottleneck effect</u>
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Explanation:
Genetic drift has an important impact on the small populations. mutations, which are spontaneous heritable changes in the genetic code, made up of DNA. Here, mutations accumulate over time in a group, modifying the distribution of alleles or various forms of a gene. Natural selection may result in a loss of diversity in a population called genetic drift; one trait's allelic frequency rises while others become less prevalent. Typically such differences exist because of occurrences of mutation and recombination.
Some mutations or alleles may become extinct from the population.
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Variants of a gene accumulate and are transmitted across generations; the frequencies of these occurrences are altered and become more stable in genetic drift- they become genetically distinct and may eventually form a new species after isolation. This may be further compounded through other phenomena such as the founder effect where a group separates and genetic diversity decreases; and the bottleneck effect where barriers to reproduction or the die-off a population increases genetic drift.
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