Biology Test 221

Morphological and biochemical studies indicate that plasma membranes (PM) are derived from nuclear membranes (NM) or endoplasmic reticulum (ER) via the Golgi apparatus (GA) by a process of membrane flow and differentiation.According to this concept, membranes are transferred and transformed along a chain of cell components in a subcellular developmental pathway.

A hemicellulose (also known as polyose) is a heteropolymer (matrix polysaccharide), such as arabinoxylans, present along with cellulose in almost all plant cell walls.While cellulose is crystalline, strong, and resistant to hydrolysis, hemicellulose has a random, amorphous structure with little strength. It is easily hydrolyzed by dilute acid or base as well as a myriad of hemicellulase enzymes.

The endoplasmic reticulum (smooth and rough) is an interconnected network of flattened, membrane-enclosed sacs or tube-like structure which are evenly distributed throughout the cytoplasm.

It forms a continuous membrane system with the nuclear membrane which are the extensions of the infolded plasma membrane.

An exclusion zone is a territorial division established for various case specific purposes. Per the United States Department of Defense, an exclusion zone is a territory where sanctioning body prohibits specific activities in a specific geographic area (see Military exclusion zone).

The formation of new lysosomes is depend on gogli body and golgi body synthesise depend upon endoplasmic reticulam. So this chain is called GERL complex 

Nucleolar organizers are secondary construction within the mitotic chromosome of eukaryotes . Primary constriction occur at centromere . Nucleolar organizers give rise to Nucleolus in telophase of mitosis . During late telophase , RNA polymerase I being to transcribe rRNA gene once again , & newly synthesized rRNA likely nucleates the assembly of nucleolus by recruiting pre nuclear bodies to the transcription site.
 

The synaptonemal complex (SC) is a protein structure that forms between homologous chromosomes (two pairs of sister chromatids) during meiosis and is thought to mediate chromosome pairing, synapsis, and recombination.

Telophase I, is followed by an interphase, called interkinesis, similar to the mitoticinter phase. During interkinesis the chromatin is partially uncoiled; however, there is no replication of the genetic material, because each chromosome already consists of two chromatids.

The two homologous chromosomes do not completely separate but remain attached together at one or more points as indicated by X arrangements known as Chiasmata.The displacement of Chiasmata is termed as terminalization.Terminalization is completed in Diakinesis stage.

Because during metaphase, all the chromosomes lined up on the metaphase plate and further proceeding anaphase. So it is easy to count them at that stage by counting the number of functional centromere. Because the number of chromosomes = count the number of functional centromere.