Transcript Cellular Respiration

Energy for Life Process
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Autotrophs- an organism that uses energy
to synthesize organic molecules from
inorganic substances
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Can make its own food
Includes-plants, some bacteria, and algae
Heterotrophs – must obtain energy from
source other than self
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Includes animals, humans, some plants
Photosynthesis
Capturing the energy in light
Overview of Photosynthesis
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Process by which sun’s energy is
converted into chemical energy in the form
of carbohydrates
It occurs in the
Plasma membranes of some bacteria
Cells of algae
Leaves of plants
Fig. 6.1 Journey into a leaf
Fig. 6.1 Journey into a leaf
Three stages of Photosynthesis
1. Capturing energy from
sunlight. Produces oxygen.
Light-dependent
2. Light energy converted to
reactions
chemical energy. Using energy to
make ATP and NADPH
Light-independent
3. Uses chemical energy to form
reactions
organic compounds. ATP and
The Calvin cycle
NADPH are used to power the
synthesis of carbohydrates from
CO2
6 CO2 + 12 H2O + Light energy
C6H12O6 + 6 H2O + 6 O2
carbon
dioxide
water
glucose
water
oxygen
The Chloroplast – Where all 3 stages take place
Light absorption in Chloroplasts
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Each chloroplast is made up of different
pigments
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Pigment-a compound that absorbs light
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Some pigments absorb certain colors more
strongly than others
Colors of Visible Light
Chloroplast Pigments
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Chlorophyll a
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Chlorophyll b
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Only chlorophyll a is directly involved in light
reaction of photosynthesis
helps to capture light energy
accessory pigment
Carotenoids
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accessory pigment
Carotenoids
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Accessory pigments – help organism
capture more energy
Produce – yellow, orange, red, brown
colors
Mostly seen in flowers and fruits
Also seen during fall when chlorophyll
breaks down
Absorption Spectrum of
pigments
Factors affecting photosynthesis
1.
2.
3.
Light intensity- as light intensity increases, the
rate increases until saturation
Amount of available Carbon Dioxide- as carbon
dioxide increases the rate increases until
saturation
Temperature (enzymes operate better in
favorable temperatures)- enzymes are
denatured at low and high temperatures. Rate
is optimal at mid temperatures.
So……..
Why is
Photosynthesis
important biologically?
Cellular Respiration
Overview of Cellular Respiration
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Process in which organisms make ATP (energy) by
breaking down organic compounds (carbohydrates)
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The overall process may be summarized as
C6H12O6
glucose
+
6 O2
6 CO2
oxygen
carbon
dioxide
+
6 H2 O
water
+
energy
(heat or ATP)
Cellular respiration is carried out in two stages:
Occurs in the cytoplasm
– 1. Glycolysis
– 2. Oxidation
Occurs in the mitochondria
What is ATP?
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Adenosine triphosphate (ATP) is the major
source of energy for cells
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formed when phosphate group and adenosine
diphosphate (ADP) molecule bond
Present in all living cells
ATP is formed when protons move from
inside the thylakoid to the stroma
Conditions for Cellular
Respiration
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Oxygen present – Aerobic respiration
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Majority of ATP occurs in this process
Oxygen absent – Anaerobic respiration
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No ATP created
Lactic acid fermentation
Alcohol fermentation
Harvesting Chemical Energy
Organic Compounds
Glycolysis
Fermentation
ATP
Aerobic Respiration
ATP
Glycolysis: Breakdown of Glucose
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Produces 2 ATP
Takes place in the cytosol (cytoplasm)
Process takes a molecule of glucose and
converts it into two molecules of pyruvic
acid
All organisms undergo glycolysis
Presence/Absence of oxygen drives next
set of reactions
Harvesting Chemical Energy
Organic Compounds
Glycolysis
Fermentation
ATP
Aerobic Respiration
ATP
Fermentation
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No oxygen present – anaerobic pathway
Occurs in the cytosol (cytoplasm)
No ATP is created
Regenerates an electron carrier molecule
that keeps glycolysis going = keeps ATP
in production
Harvesting Chemical Energy
Organic Compounds
Glycolysis
ATP
Without Oxygen
Fermentation
Aerobic Respiration
ATP
Lactic Acid Fermentation
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Important in manufacturing yogurt and cheese
Occurs in your muscle cells during strenuous
exercise.
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When oxygen is depleted at faster rate than can be
supplied to cells, cells switch from aerobic to
anaerobic respiration
Lactic acid accumulates in muscle cells (in cytosol)
Increased acidity in cytosol reduces cells capacity to
contract = fatigue, pains, muscle cramps
Alcoholic Fermentation
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Example - Yeast
Converts pyruvic acid into ethyl alcohol
Important to wine and beer industry
Yeast added to fermentation mixture
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Ethyl alcohol accumulates until it reaches a
concentration that inhibits fermentation
CO2 released in production of wine
CO2 retained in production of champagne
Fermentation products & the
organisms that ferment them
Yogurt/bacteria
Soy sauce/fungus
Bread/fungus
Aerobic Respiration
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Oxygen present
Occurs in cytosol in prokaryotes
Occurs in mitochondria in eukaryotes
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Krebs Cycle and Electron Transport Chain
Produces up to 36 ATP molecules
Our bodies use ATP at a rate of one
million molecules per cell per second
Harvesting Chemical Energy
Organic Compounds
Glycolysis
Fermentation
ATP
With Oxygen
Aerobic Respiration
ATP
Energy Requirements
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Present day unicellular organisms can
acquire enough energy from anaerobic
pathways
Large multicellular organisms must
acquire energy from aerobic pathways.
Do plants carry out cellular
respiration?
Yes!
Cellular respiration does not mean breathing
– it is breaking down organic compounds
to release stored energy.
Equation for Cellular Respiration
C6H12O6 + 6O2
6CO2 + 6H2O + ATP
Reactants = Glucose (sugar), Oxygen
Products = Carbon dioxide, Water, Energy