Answer:
A
Explanation:
ECM proteins are significant in the development of the extracellular matrix which is responsible for supporting and connecting cells together in the formation of tissues. The extracellular matrix is also a major component of connective tissue that is composed of collagen fibers connecting tissues. Mutations of these proteins will result in connective tissue disorders such as scurvy, sarcomas, systemic lupus erythematosus (SLE) and etcetera.
Sister chromatids first appear during the S phase of the cell cycle.
Transcription is the transfer of genetic information from DNA to RNA, and it happens in the nucleus. We can automatically rule out B. B is incorrect because it doesn't make sense; how can a process stop before it even begins?
A. I believe this is incorrect because mRNA is involved when the genetic information needs to leave the nucleus. mRNA would take it to a ribosome outside of a nucleus. Since transcription happens in the nucleus, mRNA is irrelevant before it starts.
C. This doesn't really make sense. mRNA carries information from the DNA, but not vice versa (in these early stages).
D. This would make the most sense, since RNA polymerase needs to attach to the promoter on the strand before transcription can begin.
Answer:
Cross overs can lead to formation of chromosome pairs that have no mutant allele.
Explanation:
Cross overs can lead to formation of chromosome pairs that have no mutant allele.
For example -
Suppose "X" is a mutant allele and "x" is a mutant free allele.
Now when two homologous chromosomes contains a single mutant allele in different parts of the chromosome are crossed the following offspring are produced
X x
X XX Xx
x Xx xx
"xx" is a mutant free genotype.
Thus, crossing over can create a single mutation-free chromosome
