Organisms living cells

Cell is the structural and functional unit of all living organisms known This is the smallest unit of living organisms that are classified as and often called the building blocks of life Some organisms like bacteria are unicellular (consist of one cell) Other agencies such as humans are multicultural (Humans have about 100 trillion or 1014 cells a typical cell size is 10 microns a typical cell mass is 1 monogram) Tues largest known is the ostrich egg is not fertilized

General principles

Each cell has at least some 'independent and self-care: You can take in nutrients convert nutrients into energy carry out specific functions and reproduce if necessary Each cell set up your own store instructions to execute each activity

All cells have different capabilities:

Reproduction by cell division (binary fission / mitosis or meiosis)

• Use of enzymes and other proteins encoded by genes and DNA intermediates generated by the messenger RNA and ribosome's

• Metabolism including taking the raw materials building cell components modifying energy molecules and releasing by-products Cell operation depends on its ability to extract and use chemical energy stored in organic molecules This energy is released and then used in metabolic pathways

• response to external and internal stimuli such as changes in temperature pH or nutrient levels

• Cell contents are contained in the cell surface membrane that consists of two layers of lipids with proteins embedded in it

Some prokaryotic cells contain membrane-bound compartments is important internally but eukaryotic cells have a special compartment of an internal membrane