Random rearranging of alleles on chromosomes that occurs as a result of homologous pairs lining up during metaphase is known as independent assortment and is a factor in genetic diversity. Cytokinesis is the physical process for cell division. Glycolysis is the process of breaking down sugars to generate ATP. G1 phase is the first of four phases of the cell cycle that takes place in eukaryotic cell division. Mitosis only has one metaphase, since the question stem indicates metaphase I, we know that the overall process is meiosis, during which there are two cell divisions.

Meiosis produces four genetically different haploid cells, which have half the chromosomes of diploid cells. Diploid cells are produced by mitosis. Transcription produces messenger RNA, and translation produces a chain of amino acids that is protein.

Only meiosis produces daughter cells that have half the number of copied chromosomes as the parent cells. This occurs in meiosis II and the importance of having daughter cells that are haploid is that fusion of those cells during sexual reproduction will create a cell with a normal amount of copied chromosomes (diploid), not more or less. Since mitosis deals with asexual reproduction there is no need to make haploid daughter cells.

Mitosis and meiosis, then, are two forms of cellular division and like all processes they can have problems.

DNA is both replicated (interphase) and pulled apart (anaphase) in both processes. Meiosis just goes through the cycle an additional time.

Finally, microtubules are the main component in the mitotic spindle for both meiosis and mitosis.

During anaphase I, it is just like mitosis. There is a pair of homologous chromosomes (two X's) and they separate into two daughter cells. Anaphase II is a continuation of cellular division so instead of separating a pair of homologous chromosomes it separates sister chromatids of one chromosome (one X) into two daughter cells.

The stages of meiosis are just like mitosis except that the division is done twice for every cell and that there are roman numerals for each division (I = 2n to 2n, II = 2n to n).

Overall, there will be four daughter cells for each parent cell in meiosis. For mitosis there are only two daughter cells for each parent cell.

Seeing as peptide hormones are generally large, water-soluble molecules, they cannot transverse the phospholipid membrane. Instead, they must act through a membrane-bound protein receptor. Steroid hormones are generally small, fat-soluble organic molecules that can easily travel through the phospholipid membrane and the nuclear membrane. They can then act on transcription factors or interact directly with DNA. Both peptide and steroid hormones initiate changes within the cell; they simply do so by different mechanisms.

After a ligand binds to receptor tyrosine kinases, the receptors need to form a dimer to foster activation of their tyrosine kinase activity. After dimerization, a phosphate is transferred from ATP to the amino acid tyrosine at specific sites on the cytoplasmic region of receptor. The phosphorylation of the tyrosines provides a site where other cellular proteins can bind and further relay the signal from the receptor to the cell.

Intracellular receptors are found in the cytoplasm of the cell. Ligands for intracellular receptors are usually small molecules that can pass through the cell membrane, and include substances such as steroid hormones. Upon binding and activation, intracellular receptors bind specific DNA motifs in the nucleus and function as transcription factors, directly changing expression of genes.

In contrast, transmembrane receptors are embedded in the plasma membrane and bind extracellular ligands to mediate intracellular responses. Ligand binding to transmembrane receptors often initiates a signal cascade or mediates channel activity within the membrane of the cell.

Calcium is a widely used second messenger of signal transduction. Calcium ions can function as a second messenger because its concentration within cell cytosol is much lower than outside the cell, and it is actively transported out of the cell by protein pumps. Modulation in calcium levels is used to transmit signals from both G protein and receptor tyrosine kinase signaling cascades and is involved in such functions as muscle contractions and synaptic signaling.

The other common second messenger molecule is cAMP.

Tyrosine kinase receptors are fully activated when they bind to an extracellular ligand, dimerize, and then autophosphorylate at tyrosine residues on the C terminus. The signal is not transduced until relay proteins are phosphorylated by the tyrosine kinases. These relay proteins can then stimulate a phosphorylation cascade that initiates signaling pathways, which regulate nuclear gene transcription