Gene expression begins with transcription and occurs in the <u>nucleus.</u> To create an <u>RNA molecule,</u> the DNA sequence of a gene must be copied. <u>RNA polymerases, </u>which join nucleotides to create an RNA strand, carry out transcription (using a DNA strand as a template).<u> Initiation, elongation, and termination</u> are the three phases of transcription.
- RNA polymerase is the enzyme responsible for constructing the messenger RNA transcript from the template DNA.
- The synthesis of mRNA always proceeds in a 5’ to 3’ direction. In eukaryotes, the nucleus is the site of mRNA synthesis, whereas, in prokaryotes, mRNA is formed in the cytoplasm. The process of transcription has three stages:
Initiation stage – RNA polymerase begins the synthesis by recognizing the gene present at the beginning of the template strand.
The polymerase binds to the specific sequence, which at present at the initial end of the template. These are called consensus sequences. Specific transcription factors facilitate the recognition and binding of the consensus sequence with RNA polymerase.
Elongation stage – the RNA polymerase copies the mRNA complementary to the coding strand. The process of elongation continues till the RNA polymerase reaches the terminal sequence. Certain factors facilitate the elongation process called extension factors.
Termination stage – RNA polymerase, upon reaching the termination sequence, stops the transcription. At this point, no more elongation is carried out. The nascent mRNA is released from the transcription bubble by either of the two processes:
- By formation of a hair loop structure that pulls the mRNA from the transcription complex or,
- A protein called Rho utilizes ATP to break the bonds and release the nascent mRNA.
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Answer:
A homozygous dominant trait will have both the dominant alleles of a gene for a trait. For example, the AA genotype of the 80 brown gerbils.
A heterozygous trait will have one dominant and one recessive allele for the particular gene. For example, the Aa genotype of the 64 brown gerbils.
A recessive trait will be the trait in which there is no dominant allele for the gene. The suppressed trait only occurs when both the alleles of the gene are recessive. For example, the aa genotype of the black gerbils.
The completed table is shown in the attachment.
Answer:
miotic, first growth, second growth, synthesis
Explanation:
Answer:
Differentiation occurs numerous times during the development of a multicellular organism as it changes from a simple zygote to a complex system of tissues and cell types