Tiara

The Cell Theory States: The cell is the basic unit of life. All living organisms are composed of cells, they may multicellular or unicellular. Cells arise from pre-existing cells. More Modern Concepts State: Energy flow occurs within the cells. DNA is passed from cell to cell. All cells have the same basic chemical composition.

Actually, intracellular is really called Cytosol. Cytosol contains dissolved nutrients, ions, waste products, and soluble and insoluble proteins. The cell membrane keeps the intracellular fluid away from the extracellular fluid. Extracellular fluid is what our cell floats around and about in. It’s a watery substance, and like it was previously stated, the cell membrane separates the extracellular from the intracellular fluid.

STRUCTURE: The cell membrane is basically a wall that separates the interior of cells, from the outside atmosphere. It is selectively permeable to organic molecules and ions. It protects the cell from the outside forces, and consists of the lipid bilayer with embedded proteins/ IMPORTANCE: The cell membrane anchors the cytoskeleton to provide a shape to the cell. It also attaches to the extracellular matrix and other cells to form tissues.

Cells interact with their environment through many ways. The cells needs to obtain nutrients from the environment, maintain water balance with their surroundings and to remove the waste materials from within the cell. The plasma membrane keeps a boundary between any cell and its environment.

The membranous organelles are listed below: Mitochondria, Nucleus, endoplasmic reticulum, Golgi apparatus, lysosomes, and peroxisomes. MITOCHONDRIA : small organelles that have an unusual double membrane. NUCLEUS : the control center for cellular operations. ENDOPLASMIC RETICULUM : a network of intracellular membranes. GOLGI APPARATUS : consists of flattened membrane discs, called saccules, and contains of five to six of them. LYSOSOMES : vesicles that are filled with digestive enzymes. PEROXISOMES : are smaller than lysosomes and carry a different group of enzymes. The non-membranous organelles are the following: Cytoskeleton, microvilli, centrioles, cilia, flagella, and ribosomes. CYTOSKELETON : is an internal protein framework that gives the cytoplasm strength, and flexibility. MICROVILLI : small, finger-shaped projections of the cell membrane. CENTRIOLES : are cylindrical structures composed of short microtubules. CILIA : contain nine pairs of microtubules that surround a central pair. FLAGELLA : resemble cilia, but larger, they move a cell through surrounding fluid. RIBOSOMES : small, dense structures that cannot be seen clearly with the light microscope.

The nucleus is the control center for cellular operations. The nucleus directs processes that take place in the cytosol and must receive information about the conditions and activities in the cytosol. The nucleus has many parts surrounding itself, including: the nuclear envelope, nuclear space, nuclear pores, nucleoplasm, nucleoli, and nucleosome. Most cells have one nucleus, but some are an exception and have many nuclei.

Cells divide through a process called Mitosis and Meiosis. People know cell division, and they mean mitosis, which is the process of making new body cells. Meiosis is the cell division that makes sperm and egg cells. INTERPHASE G1 : a cell that is going to divide first. S-Phase : cell duplicates its chromosomes for next 6-8 hours. G2: last minute protein synthesis. MITOSIS Prophase: begins when chromosomes coil tightly together and become visible as individual structures. Metaphase: chromosomes move to a narrow central zone called metaphase plate. Anaphase: chromatid pairs separate and daughter chromosomes move toward opposite ends of cell. Telophase: Nuclear membranes form, nuclei enlarge, and chromosomes gradually uncoil. Cytokinesis: separation of daughter cells.

Transmembrane potential is the difference in voltage between the interior and exterior of a cell.