Chapter 3 Structure and Function of Cells Metabolism Cell respiration Anabolism Catabolism Cell respiration Aerobic Anaerobic

Cells Are Classified by Internal Organization Eukaryotes have Plasma membrane Nucleus: information center Cytoplasm: fluid within membrane Organelles: structures with specialized functions Prokaryotes have No nucleus No true organelles

Cell Structure Reflects Cell Function Muscle cells Contain numerous organelles providing energy needed for muscle contraction Nerve cells Long and thin to carry impulses over distance

The Plasma Membrane Extracellular environment Receptor protein Channel protein (always open) Gated channel protein (closed position) Carbohydrate groups Cytoskeleton filaments Phospholipid Lipid bilayer Transport protein Glycoprotein Cytoplasm Cholesterol Figure 3.5

Structural Features of the Plasma Membrane Lipid bilayer Phospholipids: polar head and nonpolar tail Cholesterol: makes membrane a bit more rigid Proteins: provide means of transportation through membrane Carbohydrates: recognition patterns for cells and organisms

Diffusion: Passive Transport Through Membrane No energy required Diffusion Movement from area of high concentration to low Figure 3.6

Osmosis: Diffusion of Water Osmosis: net diffusion of water across a semipermeable membrane Figure 3.7

Variations in Tonicity Isotonic Extracellular and intracellular ionic concentration equal Hypotonic Extracellular ionic concentration less than intracellular Hypertonic Extracellular ionic concentration more than intracellular

Tonicity Figure 3.13a

Internal Structures of an Animal Cell Cytosol Semifluid gel material inside the cell Peroxisome Destroys cellular toxic waste Nucleus Information center for the cell. Contains DNA Centrioles Microtubular structures involved in cell division Cytoskeleton Structural framework of the cell Smooth endoplas- mic reticulum Primary site of macromolecule synthesis other than proteins Rough endoplas- mic reticulum Primary site of protein synthesis by ribosomes Golgi apparatus Refines, packages, and ships macromolecular products Secretory vesicle Membrane-bound shipping container Ribosomes Site of protein synthesis Plasma membrane Controls movement of materials into and out of cell Mitochondrion Produces energy for the cell Lysosome Digests damaged organelles and cellular debris Figure 3.14

Endoplasmic Reticulum (ER) and Ribosomes Figure 3.16

Golgi Apparatus Receives substances from ER, refines and packages them Smooth ER Golgi apparatus Vesicle Lysosome Secretory vesicle Plasma membrane Figure 3.17 (1 of 2)

Vesicles Ship and Store Cellular Products Harmless waste Vesicles Ship and store cellular products Secretory membrane-bound spheres Examples: secretory, endocytic, peroxisomes, lysosomes Alcohol Peroxisome Golgi apparatus Cell toxic waste Lysosome Residual body Bacterium Plasma membrane Figure 3.18

Mitochondria: Provide Energy to the Cell Double membrane Inner membrane contains enzymes that break down foods Liberated energy is used to create ATP Figure 3.19a

Energy Storage Fat Glycogen Triglycerides Long-term energy storage in animals Glycogen Carbohydrate storage Short-term energy storage in animals

Cytoskeleton Supports the Cell Microtubules Microfilaments Figure 3.20

Cell Structures for Support and Movement: Cilia, Flagella, Centrioles Cilia and flagella Used in movement 9 + 2 microtubule arrangement Centrioles Used in cell division Figure 3.20

Cells Use and Transform Matter and Energy: Two Basic Metabolic Pathways Anabolism Requires enzymes Making/assembling large molecules May require energy (ATP)

Cells Use and Transform Matter and Energy: Two Basic Metabolic Pathways Catabolism Requires enzymes Breakdown of molecules May release energy Used in breaking down nutrients and recycling cell components

Cellular Respiration: Cells Use Glucose and Oxygen to Supply ATP Glucose provides energy for the cell Figure 3.23

Stages of Cellular Respiration Glycolysis: in cytoplasm Splits glucose Produces two ATP and two pyruvate molecules Citric acid cycle: in mitochondria Also called the Krebs cycle Extracts high-energy electrons Produces two ATP and carbon dioxide Electron transport system: in mitochondria Energy from electrons is used to produce ATP Produces water and carbon dioxide

Cellular Respiration: Overview Figure 3.29a

The Preparatory Step Figure 3.26

Fats and Proteins: Additional Energy Sources Figure 3.30

Fats and Proteins: Additional Energy Sources Triglycerides have twice the energy of carbohydrates Proteins Same energy as carbohydrates

Anaerobic Pathways: Energy Extraction Without Oxygen Glucose (Glycolysis) (2) ATP Lactic acid buildup Pyruvate Mitochondrial metabolism blocked without oxygen Mitochondrion Figure 3.31