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

• 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