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Chapter 9: Cellular Respiration, Chapter 10: Photosynthesis - Coggle…
Chapter 9: Cellular Respiration
Cellular Respiration
The catabolic pathways of aerobic and anaerobic respiration, which break down organic molecules and use an electron transport chain for the production of ATP
Both animals and plants experience cellular respiration
Structure of Mitochondria
Outer Membrane
A phospholipid bilayer that contains a unique collection of embedded proteins
Serves as a protective barrier, controlling the passage of ions and molecules in and out of the mitochondrion
In cellular respiration, it maintains the environment necessary for the inner membrane's functions, where ATP production occurs
Inner Membrane
Convoluted with folds
Cristae
The infoldings of the inner membrane of a mitochondrion
This structure is crucial because it provides a large surface area for the electron transport chain and ATP synthesis
Cristae house the proteins and enzymes necessary for the electron transport chain and ATP synthase, which are essential for producing ATP, the energy currency of the cell
Matrix
Located inside the inner membrane of the mitochondrion
Contains enzymes and substrates necessary for the citric acid cycle
Enzymes in the matrix catalyze various steps of cellular respiration, contributing to the production of ATP
Steps
To start, 1 glucose and 2 ATP are needed
(I accidentally clicked an extra branch and didn't know how to fix it :D)
Glycolysis
A fundamental metabolic pathway that breaks down glucose, a six-carbon sugar, into two molecules of pyruvate, each containing three carbons
Occurs in the cytoplasm and requires no oxygen
Energy Investment Phase
The cell uses 2 ATP molecules to phosphorylate glucose, preparing it for breakdown
Energy Payoff Phase
The pathway generates 4 ATP molecules through substrate-level phosphorylation, resulting in a net gain of 2 ATP.
2 NAD+ molecules are reduced to 2 NADH, capturing energy in the form of high-energy electrons
The final products from this step are 2 pyruvate molecules, 2 ATP, and 2NADH
Pyruvate Oxidation
Is an intermediate step, connects glycolysis to the citric acid cycle
No ATP needed
Occurs in the Matrix
Each pyruvate molecule (3-carbon) is converted into acetyl CoA (2-carbon)
NAD+ is reduced to NADH, capturing high-energy electrons
The final products from this step are 2 NADH and 2CO2
Kreb Cycle
Further oxidizes the organic fuel from pyruvate, which is derived from glycolysis.
Requires ATP
Occurs in the Matrix
Acetyl CoA, formed from pyruvate, enters the cycle
Coenzyme A is released
For each acetyl CoA, two molecules of CO2 are released
Three NAD+ molecules are reduced to NADH, and one FAD is reduced to FADH2
One ATP is generated per cycle turn through substrate-level phosphorylation
NADH and FADH2 carry high-energy electrons to the electron transport chain
The final products from this step are 3 NADH, 1 FADH2, 1 ATP, and 2 CO2
Oxidative Phosphorylation
Electron Transport Chain
Electrons from NADH and FADH2 are transferred through a series of protein complexes in the inner mitochondrial membrane
Complex 1
The start of the ETC
NADH ---> NADH+
Complex 2
FADH2 ---> FAD
Complex 3
Complex 4
H + e- + 1/2O ---> H2O
Mobile Electron Carrier
Q - Ubiquinone
C - Cytochrome
As electrons move through these complexes, protons are pumped into the intermembrane space, creating a proton gradient
Final stage of cellular respiration, occurring in the mitochondria. It involves two main processes: the electron transport chain (ETC) and chemiosmosis
Chemosmosis
The proton gradient generates a proton-motive force
Protons flow back into the mitochondrial matrix through ATP synthase, driving the conversion of ADP to ATP
ATP Synthase
A crucial enzyme that synthesizes ATP from ADP and inorganic phosphate using the energy from a proton gradient created by the electron transport chain
ADP ---> ATP
The final product of this step is ~32 to 36 ATP
C6H12O6 + 6O2 ---> 6H2O + 6CO2 + Energy
Fermentation/Pathways
Pathways
Aerobic Respiration
A catabolic pathway for organic molecules, using oxygen as the final electron acceptor in an electron transport chain and ultimately producing ATP
Consumes organic molecules and oxygen to yield ATP
The cells of most eukaryotic and many prokaryotic organisms can carry out aerobic respiration
Anaerobic Respiration
Allows cells to produce ATP without oxygen
Uses other molecules with a high affinity for electrons in place of oxygen
Redox Reactions
A chemical reaction involving the complete or partial transfer of one or more electrons from one reactant to another
Short of Reduction-Oxidation Reaction
O I L R I G
Oxidation
The complete or partial loss of electrons from a substance involved in a redox reaction
Reducing Agent
The electron donor in a redox reaction
Reduction
The complete or partial addition of electrons to a substance involved in a redox reaction
Oxidizing Agent
The electron acceptor in a redox reaction
Fermentation
A partial degradation of sugars that occurs without oxygen
A form of anaerobic respiration
An organic molecules (pyruvate or acetaldehyde) acts as a final electron acceptor
2 Types
Alcohol Fermentation
Pyruvate is converted to ethanol in two steps
Releases CO2 from pyruvate
Produces NAD+ and ethanol
Ex: Used in brewing, winemaking, and baking
Lactic Acid Fermentation
Pyruvate is recuded directly by NADH to form lactase and NAD+
Ex: Used in the dairy industry to make cheese and yogurt
Comparisons
Obilgate Anaerobes
An organism that carries out only fermentation or anaerobic respiration
These organisms don't have the ability to survive in an environment with O2
Facultative Anaerobes
An organism that makes ATP by aerobic respiration if oxygen is present but that switches to anaerobic respiration or fermentation if oxygen is not present
Pyruvate is a fork in the metabolic road leading to alternative catabolic routes
Under aerobic conditions, pyruvate can be converted to acetyl , and oxidation continues in the citric acid cycle via aerobic respiration
Under anaerobic conditions, lactic acid fermentation occurs
Not very efficient
NADH/NADH+ and FADH2/FAD
Converts Glucose into ATP
Electron Transport Chain
Chapter 10: Photosynthesis
Steps of Photosynthesis
Light-Dependent Reactions
The steps of Photosynthesis that convert light energy into chemical energy
Electron Transport Chain
Photosystem II
Structure
Light Harvesting Complex
Reaction Zone
Primary Electron Receptor
Pigment
Special Pair of Chlorophyll
Known as P680, best at absorbing light at a wavelength of 680
The first photosystem to function in light-dependent reactions
The light absorbed in the pigment molecules excites the electrons
The excited electrons travel through the electron transport chain
Pq - Plastoquinone
Cyt - Cytochrome Complex
Pc - Plastocyanin
Responsible for splitting water molecules
H2O ---> 1/2 O2 + 2H
Photosystem I
The second photosystem to function in light-dependent reactions
Structure
Has the same structure except the special pair of chlorophyll
Known as P700, best at absorbing light at a wavelength of 700
After electrons flow through the ETC they reach PS I
Light energy is used to reenergize the Photosystem
The electrons are then transferred to another primary electron acceptor
Fd - Ferredoxin
NADP+ Reductase
An enzyme that plays a crucial role in redox reactions
Involved in the transfer of electrons between molecules
Responsible for transferring the electrons from Fd to NADP+
NADP+ is then reduced to NADPH, one of the product of the light-dependent reactions
The electrons in NADPH are at a higher energy level, making them more available for subsequent reactions
Chemiosmosis
ATP Synthase
A vital enzyme responsible for synthesizing ATP from ADP and inorganic phosphate using the energy from a proton gradient
The process of electron moving through the ETC pumps H+ ions into the thylakoid space
This causes for the creation of a high concentration of protons
The protons then diffuse back into the stroma through ATP synthase
As protons flow through ATP synthase, the energy released drives the conversion of ADP and inorganic phosphate (Pi) into ATP
This creates the other product of the light-dependent reactions ATP
Photophosphorylation
The process of generating ATP from ADP and phosphate by means of chemiosmosis, using a proton-motive force generated across the thylakoid membrane of the chloroplast or the membrane of certain prokaryotes during the light reactions of photosynthesis
Calvin Cycle
The steps of Photosynthesis that use ATP and NADPH to convert CO2 into Glucose
Carbon Fixation
The initial incorporation of carbon from carbon dioxide into an organic compound by an autotrophic organism
1 CO2 molecule combines with RuBP (5-carbon acceptor)
This makes a 6-carbon compound that splits into two molecules of 3-PGA ( 3-carbon)
PGA - Phosphoglyceric Acid
6 3-PGA are created
RuBP - Rubisco
The enzyme responsible for this step
Reduction
A key step where energy and reducing power are used to convert carbon compounds into sugars
ATP and NADPH are used to convert 3-PGA into G3P
Oxidation
6 ATP --> 6ADP
6 NADPH ---> 6NAHP+
Each molecule of 3-PGA gains a phosphate from ATP, making a 3-carbon intermediate
Receiving 2 electrons from NADPH and losing 1 of its phosphate groups makes G3P
G3P - Glyceraldehyde
Regeneration
The final step where RuBP is regenerated for the cycle to repeat
Some G3P molecules go to make Glucose while other are recycled to regenerate RuBP acceptor
Recycled
5 G3P are rearranged into 3 molecules of RuBP
3 ATP ---> 3 ADP
Creation
1 G3P is used to make Glucose
2 G3P are need to create Glucose
Photosynthesis
The conversion of light energy to chemical energy that is stored in sugars or other organic compounds
Important Structures
Chloroplasts
Organelles that are responsible for photosynthesis
Stroma
The dense fluid found within chloroplasts, surrounded by the inner membrane
Serves as the site of the Calvin Cycle in Photosynthesis
Thylakoid
Membrane-bound structures in Chloroplasts
Serves as the site of Light-Reactions in Photosynthesis
Thylakoid Space
The interior of the Thylakoid Sacs
Serves as the site of the Proton Gradient in Photosynthesis
Grana
Stacks of membrane-bound Thylakoids within the Chloroplast
Chlorophyll
A green pigment located in membranes within the chloroplasts
Types
Chlorophyll A
The primary pigment that directly participates in the light reactions
Converting light energy into chemical energy
Chlorophyll B
Acts as an accessory pigment
Transfers energy it absorbs to Chlorophyll A
Responsible for absorbing light energy in Photosynthesis
Mesophyll and Stomata
Mesophyll
Leaf cells specialized for photosynthesis
The tissue in the interior of the leaf
Chloroplasts are mainly found in these cells
Stomata
A microscopic pore surrounded by guard cells in the epidermis of leaves and stems that allows gas exchange between the environment and the interior of the plant
In photosynthesis, CO2 enters the leaf and O2 will leave the leaf through the stomatas
Organisms
Autotrophs
An organism that obtains organic food molecules without eating other organisms or substances derived from other organisms
They can sustain themselves
They produce their organic molecules from CO2 and other inorganic raw materials obtained from the environment
Ultimate Sources of Organic Compounds
They are the primary producers in the ecosystem
They form the base of the food chain
They support all other trophic levels
Photoautotrophs
Organisms that use light energy to synthesize organic compounds
Ex: Plants and Algae
Heterotrophs
An organism that obtains organic food molecules by eating other organisms or substances derived from them
Unable to make their own food
Consumers
Primary Consumer
Herbivores that eat plants
Secondary Consumer
Carnivores that eat herbivores
Tertiary Consumer
Carnivores that eat other carnivores
Decomposers
Organisms that break down dead organic matter
6CO2 + 6H2O + Light Energy ---> C6H12O6 + 6O2
Plants
C3 Plants
Photorespiration
Generally occurs on hot, dry, bright days, when the stomata close and the oxygen to carbon dioxide ratio in the leaf increases, favoring the binding of oxygen rather than carbon dioxide by rubisco
A metabolic pathway that consumes oxygen and ATP, releases carbon dioxide, and decreases photosynthetic output
A plant that uses the Calvin cycle for the initial steps that incorporate carbon dioxide into organic material, forming a three-carbon compound as the first stable intermediate
C4 Plants
A plant in which the Calvin cycle is preceded by reactions that incorporate carbon dioxide into a four-carbon compound, the end product of which supplies carbon dioxide for the Calvin cycle
Specialized photosynthetic pathway that some plants use to improve Carbon Fixation
They preface the Calvin cycle with an alternate mode of carbon fixation that forms a four-carbon compound as its first product
This adaption is particularly beneficial in conditions where water loss is a concern and CO2 uptake needs to be max
This pathway ensures the Calvin Cycle occurs at night
CAM Plants
Plants that have adapted to survive in arid conditions by altering their photosynthetic process
CAM - Crassulacean Acid Metabolism
They open their stomata at night, and incorporate CO2 into organic acids
During the day, the stomata are closed to prevent water loss
Similar to C4 Plants, but CAM plants physically change their structure
NADPH/NADP+
Converts Light Energy into Glucose
Chemiosmosis