Letter B is correct answer that what I am thinking
The exons of the pre -mRNA contain the protein -coding regions.
Pre mRNA is the first made mRNA transcript and requires undergo many post transcriptional modifications for the formation of a mature mRNA.
The exons are the regions of the pre-mRNA that are found in the mature RNA, after the splicing of introns takes place.
RNA splicing is the process in which the non-coding segments of the RNA, which are known as introns, are removed by the help of small nuclear ribonucleoproteins. These SnRNPs make the spliceosome, which catalyzes the process of splicing.
After the introns are removed by the splicing process, the exons are covalently joined, which forms the mature mRNA.
Learn more about mRNA from here:
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Crossing over occurs at the four-strand stage when two homologous chromosomes, each consisting of a pair of sister chromatids, are paired. Each crossover involves just two of the four strands and generates two recombinant strands.
Hope this helps!
Answer:
7.5
Explanation:
The first note is a half note that is (2 beats). The second note is an 8th note (1/2 a beat). The 3rd note is a whole note (4 beats). The last note is a quarter note so (1 beat).
2+0.5+4+1= 7.5
The male
human has a sperm cell and the female has an egg cell. The cells from the male
and female that combine to form a zygote are called gametes. The human sperm
and egg cells each contain 23 chromosomes. . A combination of gametes forms a
zygote with 46 chromosomes. The type of cell division that produces gametes
with half the normal chromosome number is the meiosis. Meiosis is the type of
cell division used in sexual reproduction. It will occur in the testes and
ovaries.<span>Chromosomes get
shuffled when eggs and sperm are made. Though most adult cells contain two sets
of chromosomes, sperm and egg cells are different. These special cells have
just one chromosome from each pair. Which chromosome they get from each pair is
random, making each sperm or egg cell unique. There is also a bit of mixing
before the chromosomes are sorted into individual sperm or egg cells.
Chromosomes from each pair in a mother or father, respectively, make contact
and exchange pieces of DNA, creating hybrid chromosomes. </span>
