Cellular Respiration Overview
April 1, 2013
Learning Targets
• Students will be able to explain where
organisms get the energy they need for life
processes.
• Students will be able to define cellular
respiration.
• Students will be able to compare
photosynthesis and cellular respiration.
Bell Work
• Watch the Chapter Mystery video on page 431
at the beginning of Chapter 9.
• What adaptations do you think whales have
that allow them to go so long without
breathing?
Where do organisms get energy?
• Autotrophs – make their own food through photosynthesis.
• Heterotrophs – must consume other organisms for food.
• Food molecules contain chemical energy that is released when chemical bonds are broken.
Energy in food
• How much energy is in food?
• Varies with the type of food.– Depends on chemical
structure
• Energy in food is described in units of calories.– Amount of energy
needed to raise the temperature of 1 gram of water 1 degree Celsius.
Cells and Food Energy
• Cells break down food slowly, capturing
chemical energy at key steps
• Cellular respiration is the process that
releases energy from food in the presence of
oxygen.
Cellular Respiration
• Overall reaction for cellular respiration
• Requires oxygen and food (such as glucose)
Cellular Respiration
• Happens in a series of steps to control the
energy being released from the food.
• Energy from the reactions is stored as ATP.
Writing Break
• Do plants undergo cellular respiration? What
organelle(s) do they have that helps you
determine the answer?
Stages of Cellular Respiration
• Three main stages:– Glycolysis
– Krebs cycle
– Electron transport chain
• Most of the energy comes from the electron transport chain
Oxygen and Energy
• Oxygen is a powerful electron acceptor.
• Aerobic processes – require oxygen, such as Krebs cycle and the electron transport chain.
• Anaerobic processes – do not require oxygen, such as glycolysis
• In the absence of oxygen, fermentation keeps glycolysis going to provide ATP for cellular activity
Mitochondria
• Mitochondria are organelles that convert
chemical energy in food to usable energy for
the cell.
• Glycolysis generally occurs in the cytoplasm,
but the Krebs cycle and the electron transport
chain take place inside the mitochondria.
Writing Break
• Make a flowchart that shows the different
steps of cellular respiration.
• Chapter mystery clue – If whales remain
underwater for 45 minutes or more, do you
think they rely primarily on aerobic or
anaerobic pathways?
Photosynthesis and Cellular Respiration
• Photosynthesis removes CO2 from the air and cellular respiration puts it back. Photosynthesis releases O2 into the atmosphere and cellular respiration uses that oxygen to release energy from food.
Assessment
• Questions:
– Why do food molecules differ in the amount of energy they contain?
– Write the overall reaction for cellular respiration.
– In what ways are cellular respiration and photosynthesis considered opposite processes?
– The Greek word glukus means “sweet” and the Latin word lysis refers to a process of loosening or decomposing. Based on this information, write a definition for the word glycolysis.
• Analyzing Data activity – page 433 “You are what you eat”