Download The Living Cell

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