Functional Anatomy of Prokaryotic and Eukaryotic Cells 4 Functional Anatomy of Prokaryotic and Eukaryotic Cells

Prokaryotic Cells Comparing prokaryotic and eukaryotic cells Prokaryote comes from the Greek words for prenucleus. Eukaryote comes from the Greek words for true nucleus.

Prokaryote Eukaryote One circular chromosome, not in a membrane No histones No organelles Peptidoglycan cell walls Binary fission Paired chromosomes, in nuclear membrane Histones Organelles Polysaccharide cell walls Mitotic spindle

Basic Prokaryote (Bacterial) Cell Shapes Average size: 0.2 -1.0 µm  2 - 8 µm Basic shapes: Spirillum Bacillus Diplococci Streptococci Spirochete Coccobacillus

Figure 4.1 - Overview

Figure 4.1a

Figure 4.1d

Figure 4.2 - Overview

Figure 4.2a–b

Figure 4.2c

Bacillus anthracis Figure 4.3

Figure 4.4 - Overview

Most bacteria are monomorphic A few are pleomorphic Unusual shapes Star-shaped Stella Square Haloarcula Most bacteria are monomorphic A few are pleomorphic Figure 4.5

Glycocalyx – “Sugar Coat” Outside cell wall Usually sticky A capsule is neatly organized A slime layer is unorganized and loose Extracellular polysaccharide (EPS) allows cell to attach Capsules prevent phagocytosis Figure 4.6a–b

Figure 4.6 - Overview

Flagella Outside cell wall Made of chains of flagellin Attached to a protein hook Anchored to the wall and membrane by the basal body Figure 4.8a

Flagella Arrangement Figure 4.7

Figure 4.8b

Motile Cells Rotate flagella to run or tumble Move toward or away from stimuli (taxis)

Motile Cells Figure 4.9

Motile Cells PLAY Animation: Bacterial Motility Figures 4.9a, 4.23d

Axial Filaments Endoflagella In spirochetes Anchored at one end of a cell Rotation causes cell to move Figure 4.10a

Fimbriae allow attachment Pili are used to transfer DNA from one cell to another Figure 4.11

Cell Wall Prevents osmotic lysis Made of peptidoglycan (in bacteria) Figure 4.6a–b

Figure 4.6a

Peptidoglycan Polymer of disaccharide N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) Linked by polypeptides Figure 4.13a

Figure 4.13b–c

Gram-Positive Gram-Negative Cell Walls Cell Walls Thick peptidoglycan In acid-fast cells, contains mycolic acid Thin peptidoglycan Outer membrane No mycolic acid

Gram + Gram - UN 4.2

Gram-Negative Outer Membrane Lipopolysaccharides, lipoproteins, phospholipids Forms the periplasm between the outer membrane and the plasma membrane. Protection from phagocytes, complement, and antibiotics

Gram Stain Mechanism Crystal violet-iodine crystals form in cell. Gram-positive Alcohol dehydrates peptidoglycan CV-I crystals do not leave Gram-negative Alcohol dissolves outer membrane and leaves holes in peptidoglycan. CV-I washes out

Damage to Cell Walls Lysozyme digests disaccharide in peptidoglycan. Penicillin inhibits peptide bridges in peptidoglycan. Protoplast is a wall-less cell. Protoplasts and spheroplasts are susceptible to osmotic lysis.

Plasma Membrane Figure 4.14a

Plasma Membrane Phospholipid bilayer Peripheral proteins Integral proteins Figure 4.14b

Fluid Mosaic Model Membrane is as viscous as olive oil. Proteins move to function. Phospholipids rotate and move laterally. Figure 4.14b

Figure 4.14c

Plasma Membrane Selective permeability allows passage of some molecules Enzymes for ATP production Photosynthetic pigments on foldings called chromatophores or thylakoids

Movement Across Membranes Simple diffusion: Movement of a solute from an area of high concentration to an area of low concentration. Facilitative diffusion: Solute combines with a transporter protein in the membrane.

Movement Across Membranes Figure 4.17

Movement Across Membranes Osmosis: The movement of water across a selectively permeable membrane from an area of high water concentration to an area of lower water concentration. Osmotic pressure: The pressure needed to stop the movement of water across the membrane. Figure 4.18a

Movement Across Membranes  Figure 4.18a–b

Figure 4.18c–e

Movement Across Membranes Active transport of substances requires a transporter protein and ATP. PLAY Animation: Membrane Transport

Cytoplasm Cytoplasm is the substance inside the plasma membrane. Figure 4.6a–b

Nuclear Area Nuclear area (nucleoid) Bacterial chromosome Plasmids Figure 4.6a–b

Ribosomes Figure 4.6a–b

Ribosomes Figure 4.19

Inclusions Figure 4.20

Endospores Resting cells Resistant to desiccation, heat, chemicals Bacillus, Clostridium Sporulation: Endospore formation Germination: Return to vegetative state

Figure 4.21b

Figure 4.21a, step 1

Figure 4.21a, step 2

Figure 4.21a, step 3

Figure 4.21a, step 4

Figure 4.21a, step 5

Figure 4.21a, step 6

Figure 4.21 - Overview