Download CH 9 Overview

Chapter 9
Photosynthesis and Cellular
Respiration
Energy and Living Things
• Energy from the sun enters living systems when
plants, algae, and certain bacteria absorb
sunlight. Some of the energy in sunlight is
captured and used to make organic compounds
that store energy and serves as food for
organisms.
• Metabolism involves either using energy to build
molecules or breaking down molecules in which
energy is stored. Photosynthesis is the
process by which light energy is converted to
chemical energy by autotrophs (organisms that
use energy from the sun or inorganic substances
to make organic compounds.)
Breaking Down Food for Energy
• Organisms that must get energy from food
instead of directly from sunlight or inorganic
substances are called heterotrophs.
• Cellular respiration is a metabolic process
similar to burning fuel. It releases much of the
energy in food to make ATP. This ATP provides
cells with the energy they need to carry out the
activities of life.
• In cells, chemical energy stored in food
molecules is released gradually in a series of
enzyme-assisted chemical reactions.
• When cells break down food molecules, some of
the energy in the molecules is released as heat.
Much of the remaining energy is stored in
molecules of ATP. ATP delivers energy wherever
energy is needed in a cell.
ATP Stores and Releases Energy
• ATP (adenosine triphosphate) is a nucleotide
with two extra energy-storing phosphate groups.
The removal of a phosphate group from ATP
produces adenosine diphosphate, or ADP. Cells
use the energy released by this reaction to
power metabolism.
ATP -> ADP + P + energy
9.2 Photosynthesis
•
Plants, algae, and some bacteria capture about 1%
of the energy in the sunlight that reaches Earth and
convert it to chemical energy through the process of
photosynthesis.
Overview:
6CO2 + 6H2O + sunlight-> C6H12O6 + 6O2
1st Light-dependent reactions trap sunlight
2nd Electron transport chain (Light-independent
reactions) excited electrons pump H+ ions
through chain creating ATP & NADPH for
Calvin Cycle
3rd Calvin Cycle (carbon fixation) production of
glucose, 6 rounds of the cycle = 1 glucose
9.3 Cellular Respiration
• Your cells transfer the energy in glucose to
ATP through a process called cellular
respiration.
• Oxygen makes the production of ATP
much more efficient, although some ATP is
made without oxygen. Metabolic
processes that require oxygen are called
aerobic. Metabolic processes that do not
require oxygen are called anaerobic
(means “without air”).
Cellular Respiration Overview:
C6H1206 +6O2 -> 6CO2 + 6H2O + ATP
•
1st Glycolysis (anaerobic) begins to
break down glucose (in the cytoplasm of
cell)
•
2nd Citric Acid Cycle (now in
mitochondria) continue to break down
glucose, 1 ATP created for each turn of
cycle (also producing NADH+, FAD2 &
AcetylCoA)
3rd Electron Transport Chain – reactions
that continue the production of 38 ATP
•
Fermentation Follows Glycolysis in the
Absence of Oxygen, only 2 ATP produced
• Lactic Acid fermentation in muscles, by
product = lactate
• Alcoholic fermentation in yeast & some
bacteria, by products = carbon dioxide
bubbles & alcohol
• COPY TABLE 9.2 PG. 243 INTO NOTES
End of Chapter 9
• Know your vocab. terms.
• Know the steps to photosynthesis (lightdependent and light-independent)
• Know the steps in aerobic respiration
• Know what happens if O2 is not present.
• Be able to describe ATP