Answer:
In the transition of metaphase to anaphase, the cohesin complex is cleaved by the separase enzyme in a process dependent on the activation of specific proteins that trigger posttranslational modifications (i.e., protein degradation by ubiquitination). This process of cleavage enables the sister chromatids to separate and move to opposite sides of the cell
Answer: Mitosis is a type of cell division in which one cell (the mother) divides to produce two new cells (the daughters) that are genetically identical to itself. In the context of the cell cycle, mitosis is the part of the division process in which the DNA of the cell's nucleus is split into two equal sets of chromosomes.
The great majority of the cell divisions that happen in your body involve mitosis. During development and growth, mitosis populates an organism’s body with cells, and throughout an organism’s life, it replaces old, worn-out cells with new ones. For single-celled eukaryotes like yeast, mitotic divisions are actually a form of reproduction, adding new individuals to the population.
In all of these cases, the “goal” of mitosis is to make sure that each daughter cell gets a perfect, full set of chromosomes. Cells with too few or too many chromosomes usually don’t function well: they may not survive, or they may even cause cancer. So, when cells undergo mitosis, they don’t just divide their DNA at random and toss it into piles for the two daughter cells. Instead, they split up their duplicated chromosomes in a carefully organized series of steps.
Answer:
B. External respiration
Explanation:
Respiration means transport of oxygen to the cells within tissues, and the transport of carbon dioxide in the opposite direction.
Answer:
Please find the explanation below
Explanation:
Our nucleus is made up of a genetic material called deoxyribonucleic acid (DNA), which is a double-helical structure that stores the genetic information needed for the optimal functioning of any organism. DNA, alongside RNA are nucleic acids that are composed of NUCLEOTIDES subunits. The nucleotide consists of a pentose sugar (deoxyribose in DNA and ribose in RNA), nitrogenous base and a phosphate group.
However, the genetic information stored in the DNA molecule needs to be expressed in order to form useful products (proteins). This genetic expression is done in two stages viz: transcription and translation. Transcription, which is catalyzed by an enzyme called RNA polymerase is the process whereby the information stored in the DNA is used to synthesize a mRNA molecule. However, this mRNA molecule is considered pre-mature until it is processed. RNA processing occurs in three stages viz: 5' capping, polyadenylation, and splicing.
5' capping involves adding a 5' cap to the marks molecule. Polyadenylation involves adding a poly(A) tail to the mRNA molecule while splicing is the removal of introns (non coding regions) with the aid of Spliceosomes and joining of the exons (coding region). After processing, the mRNA becomes matured and ready to be translated.
Translation is the process whereby the mRNA transcript is used to synthesize a protein molecule. It occurs in the ribosomes (organelles for protein synthesis, a complex of rRNA and proteins) where the mRNA is read in a group of three nucleotides called CODON. The reading is done by the Anticodon of a transfer RNA (tRNA), which is complementary to the codon.
Translation occurs in three stages: initiation, elongation and termination. The mRNA attaches to the P site of the ribosomes (initiation) where it is attached to by a tRNA's anticodon complementary to it. The anticodon carries the amino acid corresponding the codon and shifts to the A-site. The addition of amino acid to the polypeptide chain continues (elongation) until a stop codon is encountered, which signals the end of the translation process i.e. termination. This causes the polypeptide (protein) to be released from the E-site.
The synthesized protein undergoes packaging and modification in the Golgi apparatus.
