10 m Human height Length of some nerve

10 m Human height Length of some nerve and muscle cells 0. 1 m Chicken egg 1 cm 100 µm 10 µm Most plant and animal cells Nucleus Most bacteria 1 µm 100 nm 1 nm 0. 1 nm Mitochondrion Smallest bacteria Viruses Ribosomes Proteins Electron microscope Frog egg Light microscope 1 mm Unaided eye 1 m Lipids Small molecules Atoms 1

Fimbriae Nucleoid Ribosomes Plasma membrane Bacterial chromosome (a) A typical rod-shaped bacterium Cell wall Capsule Flagella 0. 5 µm (b) A thin section through the bacterium Bacillus coagulans (TEM) 2

Outside of cell Inside of cell 0. 1 µm (a) TEM of a plasma membrane Carbohydrate side chain Hydrophilic region Hydrophobic region Hydrophilic region Phospholipid Proteins (b) Structure of the plasma membrane 3

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] Total volume [height width length number of boxes] Surface-to-volume (S-to-V) ratio [surface area ÷ volume] 6 150 750 1 125 6 1. 2 6 4

ENDOPLASMIC RETICULUM (ER) Flagellum Rough ER Smooth ER Nuclear envelope NUCLEUS Nucleolus Chromatin Centrosome Plasma membrane CYTOSKELETON: Microfilaments Intermediate filaments Microtubules Ribosomes Microvilli Golgi apparatus Peroxisome Mitochondrion Lysosome 5

NUCLEUS Nuclear envelope Nucleolus Chromatin Rough endoplasmic reticulum Smooth endoplasmic reticulum Ribosomes Central vacuole Golgi apparatus Microfilaments Intermediate filaments Microtubules CYTOSKELETON Mitochondrion Peroxisome Chloroplast Plasma membrane Cell wall Plasmodesmata Wall of adjacent cell 6

Nucleus 1 µm Nucleolus Chromatin Nuclear envelope: Inner membrane Outer membrane Nuclear pore Pore complex Surface of nuclear envelope Rough ER Ribosome 1 µm 0. 25 µm Close-up of nuclear envelope Pore complexes (TEM) Nuclear lamina (TEM) 7

Cytosol Endoplasmic reticulum (ER) Free ribosomes Bound ribosomes Large subunit 0. 5 µm TEM showing ER and ribosomes Small subunit Diagram of a ribosome 8

Smooth ER Rough ER ER lumen Cisternae Ribosomes Transport vesicle Smooth ER Nuclear envelope Transitional ER Rough ER 200 nm 9

cis face (“receiving” side of Golgi apparatus) 0. 1 µm Cisternae trans face (“shipping” side of Golgi apparatus) TEM of Golgi apparatus 10

Nucleus 1 µm Vesicle containing two damaged organelles 1 µm Mitochondrion fragment Peroxisome fragment Lysosome Digestive enzymes Plasma membrane Lysosome Peroxisome Digestion Food vacuole Vesicle (a) Phagocytosis Mitochondrion Digestion (b) Autophagy 11

Central vacuole Cytosol Nucleus Central vacuole Cell wall Chloroplast 5 µm 12

Nucleus Rough ER Smooth ER cis Golgi trans Golgi Plasma membrane 13

Intermembrane space Outer membrane Free ribosomes in the mitochondrial matrix Inner membrane Cristae Matrix 0. 1 µm 14

Ribosomes Stroma Inner and outer membranes Granum Thylakoid 1 µm 15

Chloroplast Peroxisome Mitochondrion 1 µm 16

Microtubule 0. 25 µm Microfilaments 17

ATP (a) Vesicle Receptor for motor protein Microtubule (ATP powered) of cytoskeleton Microtubule Vesicles 0. 25 µm (b) 18

10 µm Column of tubulin dimers Keratin proteins Actin subunit Fibrous subunit (keratins coiled together) 25 nm 7 nm 10 µm 8– 12 nm Tubulin dimer 19

Centrosome Microtubule Centrioles 0. 25 µm Longitudinal section Microtubules Cross section of one centriole of the other centriole 20

Direction of swimming (a) Motion of flagella 5 µm Direction of organism’s movement Power stroke Recovery stroke (b) Motion of cilia 15 µm 21

Outer microtubule doublet 0. 1 µm Dynein proteins Plasma membrane Central microtubule Radial spoke Protein crosslinking outer doublets Microtubules Plasma membrane (b) Cross section of cilium Basal body 0. 5 µm (a) Longitudinal section of cilium 0. 1 µm Triplet (c) Cross section of basal body 22

Microtubule doublets ATP Dynein protein (a) Effect of unrestrained dynein movement ATP Cross-linking proteins inside outer doublets Anchorage in cell (b) Effect of cross-linking proteins 1 3 2 (c) Wavelike motion 23

Microvillus Plasma membrane Microfilaments (actin filaments) Intermediate filaments 0. 25 µm 24

Muscle cell Actin filament Myosin arm (a) Myosin motors in muscle cell contraction Cortex (outer cytoplasm): gel with actin network Inner cytoplasm: sol with actin subunits Extending pseudopodium (b) Amoeboid movement Nonmoving cortical cytoplasm (gel) Chloroplast Streaming cytoplasm (sol) Vacuole Parallel actin filaments Cell wall (c) Cytoplasmic streaming in plant cells 25

Secondary cell wall Primary cell wall Middle lamella 1 µm Central vacuole Cytosol Plasma membrane Plant cell walls Plasmodesmata 26

Collagen Proteoglycan complex EXTRACELLULAR FLUID Polysaccharide molecule Carbohydrates Fibronectin Core protein Integrins Proteoglycan molecule Plasma membrane Proteoglycan complex Microfilaments CYTOPLASM 27

Cell walls Interior of cell 0. 5 µm Plasmodesmata Plasma membranes 28

Tight junctions prevent fluid from moving across a layer of cells 0. 5 µm Tight junction Intermediate filaments Desmosome Gap junctions Space between cells Plasma membranes of adjacent cells Desmosome 1 µm Extracellular matrix Gap junction 0. 1 µm 29

Cell Component Concept 6. 3 The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes Structure Surrounded by nuclear envelope (double membrane) perforated by nuclear pores. The nuclear envelope is continuous with the endoplasmic reticulum (ER). Nucleus Function Houses chromosomes, made of chromatin (DNA, the genetic material, and proteins); contains nucleoli, where ribosomal subunits are made. Pores regulate entry and exit of materials. (ER) Two subunits made of ribo. Protein synthesis somal RNA and proteins; can be free in cytosol or bound to ER Ribosome Concept 6. 4 The endomembrane system regulates protein traffic and performs metabolic functions in the cell Concept 6. 5 Mitochondria and chloroplasts change energy from one form to another Extensive network of membrane-bound tubules and sacs; membrane separates lumen from cytosol; continuous with the nuclear envelope. Smooth ER: synthesis of lipids, metabolism of carbohydrates, Ca 2+ storage, detoxification of drugs and poisons Golgi apparatus Stacks of flattened membranous sacs; has polarity (cis and trans faces) Modification of proteins, carbohydrates on proteins, and phospholipids; synthesis of many polysaccharides; sorting of Golgi products, which are then released in vesicles. Lysosome Membranous sac of hydrolytic enzymes (in animal cells) Vacuole Large membrane-bounded vesicle in plants Digestion, storage, waste disposal, water balance, cell growth, and protection Mitochondrion Bounded by double membrane; inner membrane has infoldings (cristae) Cellular respiration Endoplasmic reticulum (Nuclear envelope) Chloroplast Peroxisome Rough ER: Aids in synthesis of secretory and other proteins from bound ribosomes; adds carbohydrates to glycoproteins; produces new membrane Breakdown of ingested substances, cell macromolecules, and damaged organelles for recycling Typically two membranes Photosynthesis around fluid stroma, which contains membranous thylakoids stacked into grana (in plants) Specialized metabolic compartment bounded by a single membrane Contains enzymes that transfer hydrogen to water, producing hydrogen peroxide (H 2 O 2) as a by-product, which is converted to water by other enzymes in the peroxisome 30