13_Cell_Structure-1

13_Cell_Structure-1 - X X X I I I I I I I I I C C C e e e l l l l l l S S S t t t r r r u u u c c c t t t u u u r r r e e e a a a n n n d d d

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Unformatted text preview: ¡ ¡ ¡ X X X I I I I I I I I I . . . C C C e e e l l l l l l S S S t t t r r r u u u c c c t t t u u u r r r e e e a a a n n n d d d F F F u u u n n n c c c t t t i i i o o o n n n : : : O O O r r r g g g a a a n n n e e e l l l l l l e e e s s s ¢ Cellular functions are facilitated by functionally specialized areas called organelles. Organelles of prokaryotes are different from those of eukaryotic cells. ¾ ¾ ¾ P P P r r r o o o k k k a a a r r r y y y o o o t t t e e e s s s Prokaryotes (e.g., bacteria and blue-green algae) belong to the kingdom Monera and are single-celled organisms. They are either autotrophs (producing their own food) or heterotrophs (using food produced by others). Prokaryotes are small, typically 1-10 &m. Prokaryotes have no nuclei and no membrane-bound organelles. N N N u u u c c c l l l e e e a a a r r r a a a r r r e e e a a a : : : n n n u u u c c c l l l e e e o o o i i i d d d The nucleoid, a dense area analogous to a eukaryotic nucleus, can be identified; it contains a single chromosome made of circular, double-stranded DNA. Small, circular DNA fragments called plasmids are also present. rib o s o m e n u le o id c ir c u la r D N A p la s m id c e ll w a ll p illu s C C C e e e l l l l l l w w w a a a l l l l l l Outside the cell membrane, a prokaryotes has a cell wall made of glucosamines: polysaccharides and rare amino acids covered by an outer layer made of lipids. P P P i i i l l l l l l i i i Many prokaryotes have pilli, proteinous extensions used for anchoring the cells. F F F l l l a a a g g g e e e l l l l l l u u u m m m To facilitate rapid motion, some bacteria have developed proteinous machinery, the flagellum, resembling a long twirling tail whose rotation propels the cell at high rates. R R R i i i b b b o o o s s s o o o m m m e e e s s s mRNA Ribosome Protein ¡ Ribosomes are RNA-protein complexes responsible for protein synthesis. ¾ ¾ ¾ E E E u u u k k k a a a r r r y y y o o o t t t e e e s s s Eukaryotes comprise four kingdoms of organisms: (i) Protista (algae, protozoa), (ii) Fungi, (iii) Plantae, (iv) Animalia. With exception of the Protista, evolution has gone multicellular. Why?...
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This document was uploaded on 11/02/2011 for the course BIO bsc2010 at FSU.

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13_Cell_Structure-1 - X X X I I I I I I I I I C C C e e e l l l l l l S S S t t t r r r u u u c c c t t t u u u r r r e e e a a a n n n d d d

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