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Cellular Respiration + Photosynthesis
CO2 + H2O + energy C6H12O6 +O2
C6H12O6 +O2 CO2 + H2O + energy
ATP
light
Respiration
Photosynthesis
energy
CO2
H2O O2
sugar
energy
Learning Outcomes
Describe oxidation and reduction reactions Describe the basic features of glycolysis, the Kreb’s cycle, and electron transfer phosphorylation Be able to generate a balance sheet of chemicals produced for each stage of respiration Explain electron transfer chains and the end result
Explain how ATP is generated during respiration
Describe the difference between anaerobic and aerobic respiration Describe the fate of the food you eat
Cellular Respiration -- Overview
Cellular respiration is a series of oxidation-reduction reactions
C6H12O6 +O2 CO2 + H2O + energy
Lungs
Transported in bloodstream
Muscle cells carrying out
Breathing
Glucose + O2 ➞ CO2 + H2O + ATP Cellular Respiration
O2
O2
CO2
CO2
It takes about 10 million ATP per second to power a muscle cell.
What gases besides oxygen do we breathe, and are they essential?
Gases – concentration N2 78.0% O2 20.9% Ar 0.9% Others 0.2-0.4%
CO2, H2O
Reduced compounds are HIGH energy
Oxidized compounds are LOW energy
C
H
H H
H
C
H
H H
H
O C
O
O
Oxidation – loss of electrons
Reduction – gain of electrons
Loss of electrons
Gain of electrons
(Glucose) C6H12O6 + 6 O2 6 CO2 + 6 H2O + ATP
https://youtu.be/e6Xxz-VBE6s
Cellular Respiration -- Overview
https://youtu.be/ZiyH-lTyAAM
cytoplasm
mitochondrion
Cellular Respiration Occurs in Small Steps
WHY ??? Because it is much more efficient.
glucose
carbon dioxide
+ water
H+ e–
e–
oxygen
C6H12O6 +O2 CO2 + H2O + energy ATP
Energy from Glucose is Transferred to ATP
Energy from Glucose is Transferred to ATP
NAD+ + electrons + H+ NAD+ + electrons H+
Energy from Glucose is Transferred to ATP
electron carriers make it all possible
Metabolism
A series of chemical reactions form a metabolic pathway. Each reaction in the series is catalyzed by a specific enzyme. Most metabolic pathways are similar in all organisms. Some metabolic pathways take place in organelles in eukaryotes.
Glycolysis
Glycolysis occurs in the cytoplasm
Balance Sheet for Glycolysis
2 ATP
4 ATP 4 ADP + P
Input Output
glucose
2 NAD+
2 pyruvate
2 NADH
NET GAIN 2
The Krebs Cycle & Electron Transport
The Kreb’s Cycle occurs in the inner matrix
pyruvate coenzyme A
coenzyme A acetyl–CoA
CO2
CO2
CO2
ADP + Pi
Acetyl–CoA Formation and the Krebs Cycle
Balance sheet for the Krebs Cycle
2 ATP 2 ADP + 2 P
Input Output
6 NAD+ 6 NADH
2 acetyl groups
2 FAD
4 CO2
2 FADH2
Electron Transport Electron carriers transfer high energy e- to electron transport chain Energy is used to pump H+ across the inner membrane This creates an electrochemical gradient – a form of potential energy
ELECTRON TRANSFER PHOSPHORYLATION
electron transfer chain
ADP + Pi
2H2O intermembrane space
inner membrane
matrix
outer membrane
cytoplasm
O2
Both the inner and outer membranes are lipid bilayers.
ATP Synthesis
1) ATP Synthase contains a H+ channel
2) As H+ move through the channel, potential energy is converted to kinetic energy
3) The kinetic energy is coupled to ATP synthesis
Balance Sheet for Respiration
C6H12O6 +O2 CO2 + H2O + energy
How long can we survive without water?
Depends on your kidneys
Humans -- ~ 3 – 5 days
kangaroo rat
They get all the water they need from metabolic water.
Fermentation
so cell can keep making ATP without O2
recycles NAD+
Figure 7-8c p123
What makes muscles sore after exercise?
So, all we need to eat is glucose??
In addition to protein, carbohydrates, and lipids – foods supply many other key nutrients.
Micronutrients
Photo credit: Marie C. Fields/Shutterstock
Photosynthesis
Learning Outcomes
Describe electromagnetic radiation and the importance of visible radiation to photosynthesis Describe structure of chloroplasts and the location of photosynthetic reactions Describe the light reactions of photosynthesis and how ATP and NADPH are made Explain how plants are able to produce oxygen as a by-product of photosynthesis Explain the Calvin cycle and how ATP and NADPH are used to make PGAL
CO2 + H2O + energy C6H12O6 +O2
C6H12O6 +O2 CO2 + H2O + energy
ATP
light
Respiration
Photosynthesis
Oxidation – loss of electrons
Reduction – gain of electrons
Becomes reduced
Becomes oxidized
6 CO2 + 6 H2O C6H12O6 + 6 O2
Photosynthesis occurs in Chloroplasts
two outer membranes of chloroplast
stroma
part of thylakoid membrane system:
thylakoid compartment, cutaway view
Photosynthesis uses Light
Visible light is one type of electromagnetic radiation
Shorter wavelength Longer wavelength Lower energy Higher energy
Electromagnetic Radiation
Wave and particle components
Particles of visible light are called photons
Photosynthesis uses Light
Atmosphere
Sunlight
Some heat energy escapes into space
Radiant heat trapped by CO2 and other gases
https://youtu.be/PMtC34pzKGc
Photosynthesis uses Light
Plant pigments absorb specific wavelengths of light
chlorophyll b β-carotene
phycoerythrobilin phycocyanobilin
400 nm 500 nm 600 nm 700 nm
chlorophyll a
Amou
nt o
f lig
ht a
bsor
bed
Photosynthesis uses Light
Plants have many pigments.
Photosynthesis involves two pathways Light reactions convert light energy into chemical
energy (in ATP and the reduced electron carrier NADPH).
Carbon-fixing reactions use ATP and NADPH
from the light reactions, along with CO2, to produce carbohydrates.
NADPH, ATP light-
dependent reactions
oxygen
light energy water carbon dioxide
light-independent
reactions
chloroplast
NADP+, ADP
What happens when a plant pigment absorbs a photon?
The photon energy is used to “excite” an electron in chlorophyll.
The excited electron is used by an e- transfer chain.
What happens when a plant pigment absorbs a photon?
ATP synthase
What happens when a plant pigment absorbs a photon?
Light Rxns Produce ATP and NADPH
NADP+ is the electron carrier in Photosynthesis
The Calvin Cycle Synthesizes PGAL
The energy from sunlight – captured in ATP and NADPH is use to build a new organic molecule
The Calvin Cycle takes place in the stroma of the chloroplast.
NADPH, ATP light-
dependent reactions
oxygen
light energy water carbon dioxide
light-independent
reactions
chloroplast
NADP+, ADP
Where is photosynthesis happening?
OR – What fraction of light energy hitting the earth is turned into chemical energy by photosynthesis?
How efficient is photosynthesis?
~5%
What happens to the rest? not the right wavelength don’t hit a pigment molecule in the plant lost in conversion of ATP and NADPH to glucose
Despite that 5% efficiency --
How efficient is photosynthesis?
Photosynthesis converts ~104.9 petagrams of carbon per year into biomass that is 104.9 x 1015 grams or 23.1 x 1015 lb or 23.1 quadrillion pounds
Scale – grams of carbon per square meter per year
Net Primary Production
