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Cellular Respiration & Photosynthesis - Coggle Diagram
Cellular Respiration & Photosynthesis
Cellular respiration
The release of chemical energy to fuel cellular activity
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy( ATP + heat)
Catabolic pathways
Aerobic respiration
- consumes organic molecules & O₂ which yields ATP
Redox reactions
- chem. reaction involving the transfer of 1 or more electrons from one reactant to another
Reduction agent
- electron donor
Oxidizing agent
- electron acceptor
Electron Transport chain
- sequence of electron carrier molecules that shuttle electrons down a series of redox reactions that releases energy used to make ATP
Fermentation
- partial degradation of sugars that occur without O₂
Glycolysis
- series of reactions that splits glucose into pyruvate, occurring in the cytoplasm
Citric acid cycle/Krebs cycle
- chem. cycle involving 8 steps that completes metabolic breakdown of glucose molecules by oxidizing acetyl Coca from pyruvate
Oxidative phosphorylation
- Production of ATP using energy from the
redox reactions
of an
ETC
Substrate-level phosphorylation
- enzyme-catalyzed formation of ATP by direct transfer of a phosphate group to ADP
Glycolysis → pyruvate oxidation → Krebs cycle → electron transport chain
After glycolysis
After the oxidation of pyruvate, it is converted into acetyl CoA
The Krebs cycle acts as metabolic furnace that further oxidizes organic fuel derived from pyruvate
Glucose → NADH → ETC → proton - motive force → ATP
NADH → NAD+/H+ FADH₂ → FAD+/H+/H- are high energy carrying molecules
Chemiosmosis couples electron transport to ATP synthesis
Cytochromes (C)
- iron-containing protein that is a component of ETCs
Ubiquinone(Q)
- compound that carries electrons in the ETC
ATP synthase
- an enzyme that makes ATP from ADP & inorganic phosphate
Chemiosmosis
– process that uses a H⁺ gradient across a membrane to drive cellular work like ATP synthesis
Proton-motive force
– energy stored as a proton gradient across a membrane, created by pumping H⁺ ions during chemiosmosis
ATP production without O₂
Fermentation
is an extension of
glycolysis
that oxidizes NADH by transferring electrons to pyruvate or its derivatives. There are 2 common types
Alcohol fermentation
- with 2 steps, pyruvate is converted to ethanol. 1. releases CO₂ from pyruvate. 2. produces NAD+ & ethanol
Lactic acid fermentation
- pyruvate is reduced directly by NADH to form lactate & NAD+ (occurs in animals)
Anerobic respiration
- uses an ETC with a final electron acceptor other than oxygen
Fermentation, anaerobic, & aerobic
Similarities
All use glycolysis (net ATP=2) to oxidize glucose
NAD+ is the oxidizing agent that accepts electrons during glycolysis
Obligate anaerobes
- required to undergo CR without O₂
Facultative anerobes
- can undergo CR with or without O₂
If O₂ is present then pyruvate happens
Fatty acids are broken down by beta oxidation & yield acetyl CoA, NADH, &FADH₂
Cellular respiration begins with
Glucose (C₆H₁₂O₆)
Glyco
Releases
2 Net ATP (burns 2 ATP, produces 4 ATP)
Breaks chemical bonds
Does not require O₂
Fermentation
starts if there is no O₂
Oxygen (6O₂)
lysis
Occurs in the cytoplasm
Produces
2 NADH molecules
Also goes into
2 Pyruvate molecules (3-C per pyruvate molecule)
Goes into
Pyruvate
produces
Acetyl CoA
2 CO₂
2 NADH
Also goes into
Goes through Krebs cycle twice (once for each pyruvate molecule)
oxidation
Krebs cycle
Breaks down pyruvate further
Produces
2 FADH₂ molecules total
6 NADH molecules
electrons
Goes in to
Electron transport chain/chemiosmosis
3 more items...
Releases
2 ATP
6O₂ Molecules
Photosynthesis
Autotrophs
- "self feeding" able to sustain without eating from other beings
Heterotrophs
- unable to make their own food, must
consume
others
"Reverse" of cellular respiration
6CO₂ + 6H₂O →(light)→ 6O₂ + C₆H₁₂O₆
Occurs only in plants, algae, and certain prokaryotes
Converts light energy to chemical energy
Occurs in chloroplasts
Stroma
- is the dense fluid surrounding
thylakoids
Chloroplasts
are double membrane organelles with a dense fluid called
stroma
Thylakoids
- connected sacs in the chloroplast that compose of a 3rd membrane system. Stacks of thylakoids are called
granum
Chlorophyll
- green pigment of leaves. Resides in the
thylakoid
. More than 1 type of chlorophyll
Mesophyll
- cells of a plant where chloroplast organelles are found
Stomata
- "mouth" of the leaf, where CO₂ enters and O₂ exits
Carbon fixation
- initial incorporation of CO₂ into an organic compound by an autotrophic organism
reaction is catalyzed by the enzyme Rubisco
1 molecule of CO₂ combines with RuBP (5 carbon acceptors). This then splits into 2 molecules of 3-PGA (made of 3-carbons)
2 stages of photosynthesis: light reactions & Calvin cycle
Light dependent reactions v. Calvin Cycle
Calvin Cycle
Occurs in the
stroma
Does NOT require light energy
ATP & NADPH are converted in
G3P
(precursor to glucose)
light dependent reactions
Continuous supply of light energy
Water is converted into O₂
Converts light energy in the form of ATP & NADP+
Occurs in the
thylakoid
membrane
Is a redox process & an endergonic process
Conversion of ATP & NADPH
Electromagnetic spectrum
- spectrum of electromagnetic radiation
Visible light
-Portion of the
EMS
that is detectible to human eyes (380 nm - 740 nm)
Wavelength
-distance between crests of waves
Photon
- a quantum of light energy that behaves like a particle
Spectrophotometer
- measures a pigments ability to absorb various
wavelengths
Absorption spectrum
- graph plotting a pigments light absorption vs.
wavelength
Types of chlorophyll
Chlorophyll a
- the key light-capturing pigment that participates directly in light reactions
Chlorophyll b
- an accessory pigment
Carotenoids
- separate group of accessory pigments
Action spectrum
- graph that profiles effectiveness of different wavelengths of radiation in driving a particular process
Photosystems
- consists of a reaction-center complex surrounded by light-harvesting complexes
named in order of discovery
Photosystem 2 is AKA P680 because it absorbs light at 680 nm
Photosystem 1 is known as P700 because it affectively absorbs light of
wavelength
at 700 nm
Light harvesting complex
Primary electron acceptor
- reaction center accepts excited electrons and is reduced as a result
Linear electron flow
- primary pathway involves both photosystems and produces ATP & NADPH using light energy
There are 8 steps
Photon hits PS2 and energy is passed among pigment molecules until it excites P680
Excited electron from P680 is transferred to the primary electron acceptor
An enzyme catalyzes the split of H₂O in 2 electrons
Increase of fluidity in membrane to allow electrons to move down the ETC is because of
Cyt
= Cytochrome
Pc
= Plastocyanin
Pq
= Piastoquinone
Fd
= Ferredoxin
Cyclic electron flow
- photoexcited electrons cycle back from Fd to the cytochrome complex instead of being transferred to NADP+
Calvin cycle uses and alternative mechanisms of carbon fixation
Photorespiration
- rubisco binds with O₂ instead of CO₂ producing a 2-carbon compound
Glyceraldehyde 3-phosphate
- 3-carbon carbohydrate, direct product of Calvin cycle
Ribulose bisphosphate (RuBP)
- carboxylase-oxygenase, the enzyme that normally catalyzes the first step of the calvin cycle
Reduction
- ATP & NADPH are used to convert 3-PGA into G3P
This intermidiate molecule then recieves 2 electrons from NADPH n& loses one of its phosphatr groups making G3P
Regeneration
- some G3P molecules go on to make glucose while others must be recycled to regenerate the RuBP acceptor
each molecule of 3GPA recieves a phosphate from ATP to make a 3 carbon intermediate molecule
3 turns of the Calvin cycle make 1 3GP
2 3GP= 1 glucose
6 turns of the Calvin cycle = 2 G3P
