the living cell chapter 21 great idea: life is based on chemistry, and chemistry takes place in...
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The Nature and Variety of CellsTRANSCRIPT
The Living Cell
Chapter 21Great 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• 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
• 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• Photosynthesis
– Convert sunlight to energy• Process
– Energy + CO2 + H2O carbohydrate + O2
• 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– CO2 produced– ATP – Energy-carrying molecules
• Result– 36-38 ATP
Cell Division
Mitosis
• Mitosis– Cell division– Not for sexual reproduction
• Chromosomes• Process
– Copy chromosomes– Spindle fibers– Migration of chromosomes– Nuclear membrane reforms
Meiosis• 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