The Cell Basics of cell biology [Presentation for t.A. screen test] Mohati Desai Dept of biology University of kentucky

The Cell Cell- basic structural, functional unit of all living organisms All living organisms are made up of cells Cells perform the various functions needed by the organism to survive

Unicellular and Multicellular Organisms Unicellular organisms: only a single cell that performs all the functions E.g. Bacteria Multicellular organisms: more than one cell and in many cases more than one type of cells; collectively perform all the functions of the organism. E.g. Higher plants and animals

Prokaryotic and Eukaryotic cells Cells are divded into two categories depending on their complexities: Prokaryotic cells and Eukaryotic cells. Prokaryotic cells: Simpler, smaller, have no membrane bound nucleus or organelles. Have outer cell wall enclosing a fluid cytoplasm. E.g. bacteria (E. coli).

Eukaryotic cells : Have a nucleus and various cell organelles; larger. E.g. plant cells, animal cells. The organelles help in compartmentalization and allow specialized functions to be sequestered and carried out in different locations.

Components and Organelles of Cells Cell membrane/ Plasma membrane: Outermost covering that confers structure, shape and protection. It is made up of lipids embedded with proteins.

Cytoplasm: Everything between the cell membrane and the nucleus. Primarily composed of water and includes salts, dissolved gases, enzymes, nutrients, proteins and all the cell organelles except the nucleus.

Nucleus: It is a dense spherical body in the cytoplasm which regulates all cell activity. It contains the genetic material (DNA) of cell. It is enclosed by a membrane known as the nuclear membrane.

Mitochondria: Known as the power house of the cell Site of aerobic respiration and energy production.

Endoplasmic Reticulum: A folded system of membranes spread throughout the cell that loop back and forth giving it a very large surface area for cell reactions. Site for protein and lipid production.

Ribosomes: Small organelles found either attached to the surface of the ER or free in the cytoplasm. Involved in protein synthesis

Golgi Bodies : Structure similar to the ER though not so large and wide spread. Responsible for processing and packaging proteins for the cell. Proteins are squeezed off into the little blebs which drift off into the cytoplasm

Others: Chloroplast, lysosomes, centrioles, vacuoles, cell wall, plastids, cilia, flagella Cilia Flagella