Celulas Procarióticas Células procarióticas [pro = antes; karyon = grano (núcleo)] Incluye bacterias y arqueobacterias. 1
Su material genético se encuentra en una región nucleoide. Figure 7.4x2 E. coli NO tienen núcleo. Su material genético se encuentra en una región nucleoide. NO tiene organelos membranosos. 2
Celulas Procarióticas Nucleoid region Bacterial cromosome Ribosomes Plasma membrane Cytoplasm Cell wall Glycocalyx Pili Flagella 0.5 µm (a) A typical rod-shaped bacterium (b) An electron micrograph of Escherichia coli Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3
¿Qué factores determinan los límites? Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 nm 0.1 nm 10 nm 100 nm 1 mm 1 cm 0.1 m 1 m 10 m Atoms Lipids Proteins Ribosomes Viruses Mitochondria Nucleus Fish egg Bird egg Human height Electron microscope Light microscope Unaided human eye Small molecules Most bacteria Most plant and animal cells 1 m 10 m 100 m Smallest 4
Límite menor
Límite mayor está impuesto por Difusión Razón Area de superficie a Volumen (A/V). 6
Surface area increases while total volume remains constant Fig. 6-8 Surface area increases while total volume remains constant 5 1 1 Total surface area [Sum of the surface areas (height width) of all boxes sides number of boxes] 6 150 750 Total volume [height width length number of boxes] Figure 6.8 Geometric relationships between surface area and volume 1 125 125 Surface-to-volume (S-to-V) ratio [surface area ÷ volume] 6 1.2 6 7
Funciones de Proteínas Membranales Signaling molecule Enzymes Receptor ATP Signal transduction (a) Transport (b) Enzymatic activity (c) Signal transduction Figure 7.9 Some functions of membrane proteins Glyco- protein (d) Cell-cell recognition (e) Intercellular joining (f) Attachment to the cytoskeleton and extracellular matrix (ECM) 8
Figure 6.8 Geometric relationships between surface area and volume 9