The CellBasics of cell biology

[Presentation for t.A. screen test]

Mohati DesaiDept 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 functionsE.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