shianne masterson Jan.12,2015
the nucleus: the control center
the nucleus is a compact sphere that is the most prominent organelle of eukaryote cells. it is separated from the cell cytoplasm by the external boundary called a nuclear envelope. its composed of two membranes. the nuclear pores are passageways through which macromolecules migrate from the nucleus to the cytoplasm and vice versa. the nucleus also contains an inner substance known as nucleolus, that strains more intensely than the immediate surroundings because of its RNA content. prominent feature of the nucleoplasm in strained preparations is a network of dark fibers known as chromatin. chromatin makes up the eukaryote chromosomes,large genetic information in the cell. during mitosis, however, when the duplicated chromosomes are separated equally into the daughter cells, the chromosomes themselves become readily visible as discrete bodies. this happens when DNA becomes highly condensed by forming coils and supercoils around the histonesto prevent the chromosomes from tangling as the separate into new cells.
Endoplasmic reticulum: A passageway in the cell
the endoplasmic reticulum is a microscopic series of tunnels used in transport and storage. there are two types, rough endoplasmic reticulum(RER) and smooth endoplasmic reticulum(SER). the RER originates from the outer membrane of the nuclear envelope extends in a continuous network throughout the cytoplasm, even to the cell membrane. the RER appears rough because all the ribosomes partly attached to its membrane surface.
Golgi Apparatus: A packaging Machine
the Golgi apparatus, also known as Golgi complex or Golgi body, is the site in the cell in which proteins are modified and then sent to their final destinations. this organelle is always closely associated with the endoplasmic reticulum both in its location and function. the Golgi apparatus connects at the site and meets with the endoplasmic reticulum and its buds off tiny membrane-bound packets pf protein called transitional vesicles that are picked up by the forming face of the Golgi apparatus.
mitchochandria: energy generators at the cell
nothing would work if the cells control center doesn't have energy. the bulk that generates most Eukaryotas is mitochondria. a single mitochondria consists of a smooth, continuous outer membrane that forms the external contour membrane that forms the external contour and the inner folded membrane nestled neatly within the outer membrane. the folds of the inner membrane is called Cristae. Cristae membranes hold the enzymes and electron carries of aerobic respiration. this is a oxygen that extracts chemical energy contained in nutrient molecules and stores it in the form of high energy molecules, or ATP. the matrix holds the DNA, ribosomes, and the pool of enzymes.
the support network
the cytoplasm of a eukaryote cell is crisscrossed by a flexible framework of molecules called cytoskeleton. this framework appears to have several functions, shape, and movement is some cells. the three main cytoskeleton elements are actin filaments, intermediate filaments, and microtubules.