The Living Cell Chapter 21 Great Idea: Life is based on chemistry, and chemistry takes place in cells

Chapter Outline The Nature and Variety of Cells How Does a Cell Work? Metabolism: Energy and Life Cell Division

The Nature and Variety of Cells

The Cell Theory All living things are composed of cells The cell is the fundamental unit of life All cells arise from previous cells

Observing Cells: The Microscope

How Does a Cell Work?

Cell Membranes –Isolate cell –Separates cell parts Transport –Individual molecules –Specific materials channels Receptors –Bind molecules Cell Wall –Plants

Plant Cell

The Nucleus Nucleus –Contains genetic material Prokaryotes –No nucleus Eukaryotes –Nucleus Double Membrane

The Energy Organelles: Chloroplasts and Mitochondria Organelle –Specialized structure in cell Chloroplasts –Energy transformation chlorophyll –Plant cells only –Double membrane Mitochondria –Produces cells energy –Double membrane –Own DNA

Cytoskeleton –Gives cell shape –Anchors –Allows movement –Transport system Within cell Structure –Strong filaments –Complex web

Metabolism: Energy and Life

The Cell’s Energy Currency Adenosine triphosphate (ATP) –Provides energy Structure –3 phosphate groups –Sugar molecule: ribose –adenine Function –Removal of phosphate group provides energy

Photosynthesis –Convert sunlight to energy Process –Energy + CO 2 + H 2 O  carbohydrate + O 2 Colors

Glycolysis: The First Step in Energy Generation in the Cell Respiration –Oxidation of carbohydrate –Retrieves energy in glucose –Aerobic Process –Glycolysis Split glucose Result –Pyruvic acid –2 ATP –2 energy carriers Convert energy carriers to 2-3 ATP –1 molecule glucose = 6-8 ATP

Fermentation: A Way to Keep Glycolysis Going Fermentation –Anaerobic –Inefficient Yeast –alcohol Animal cells –Lactic acid

The Final Stages of Respiration Krebs cycle –Glucose broken down –CO 2 produced –ATP –Energy-carrying molecules Result –36-38 ATP

Cell Division

Mitosis –Cell division –Not for sexual reproduction Chromosomes Process –Copy chromosomes –Spindle fibers –Migration of chromosomes –Nuclear membrane reforms

Meiosis –Sexual reproduction –1 cell forms 4 gametes Gametes are genetically unique Process –Copy chromosomes –Crossing over –Segregation –Segregation again Result –4 daughter cells –½ normal chromosomes

Meiosis