Organelles Definition: These are DISTINCT structures within a cell that carry out a particular function or set of functions. In PROKARYOTES: they are NOT surrounded by a membrane In EUKARYOTES: they ARE surrounded by a membrane
PROKARYOTIC CELLSCommon features:o All have a CELL MEMBRANE and a CELL WALL •CELL MEMBRANE: • A fluid system that controls what comes in and what goes out of the cell. • It is semi-permeable. •CELL WALL: • A rigid structure that protects the inner parts of the cell from mechanical damage. • It is fully-permeable.
PROKARYOTIC CELLSCommon features:o All have a CYTOPLASM •CYTOPLASM •It is the place where chemical reactions (what you know as metabolic reactions) take place. •Most of it (about 80%) is water, therefore it looks like “empty space” under the microscope.
PROKARYOTIC CELLSCommon features:o NONE have a NUCLEUS to carry genetic information… • Genetic information: A “handbook” of instructions that will inform the cell what to do: when to grow, nourish, reproduce, etc.o ALL carry genetic information is stored in a loose chromosome known as NUCELOID.
PROKARYOTIC CELLS ALL have a MESOSOME for cellular respiration The MESOSOME can be seen as an invagination of the cell membrane. It is made up of similar stuctural components.
PROKARYOTIC CELLS ALL have a RIBOSOMES for making proteins RIBOSOMES in prokaryotic cells are not attached to other structures, but can be found freely in the cytoplasm. They are seen as little “dots” lying all over.
PROKARYOTIC CELLSCommon features:o SOME have PILI… PILI: For attachment to surfaces, usually of other cells (allows transfer of info) FLAGELLA: For propulsion and movement.o SOME have FLAGELLA
Representing cells in a diagramMicrograph of E.coli Diagram of E.coli