BIO 1140 - Cell Energy Generation Flashcards
What does Photosynthesis involve?
Photosynthesis involves light and gas exchange.
Where does Photosynthesis occur?
Photosynthesis occur in chloroplasts
- two membranes
What are Chlorophyll-Containing Thylakoid membranes?
Contains light-capturing + ATP generating systems
What is a Granum?
Single thylakoid stack
- Grana for plural
What are the Two Pathways of Photosynthesis?
- The light reaction
- The carbon-fixation reaction
What is the Light Reaction?
convert light energy into chemical energy in the form of ATP and the reduced electron carrier NADPH.
- Takes place in thylakoid membrane
What is the Carbon-Fixation Reaction?
The carbon-fixation reactions (light-independent reactions) use ATP, NADPH and CO2 to produce carbohydrates.
- takes place in stroma (“matrix” of chloroplast)
How is Light Energy absorbed?
Light energy is absorbed by pigments in photosynthesis
What are Pigments?
Molecules that absorb wavelength in the visible spectrum are called pigments.
What are the Three common Photosynthetic Pigments?
Chlorophyll a, chlorophyll b and beta-carotene are common photosynthetic pigments in plants.
What is Light?
A form of electromagnetic radiation
- has a dual nature
What is the Dual Nature of Light?
- It propagates in waves but has particle-like behaviors.
- Particles of light are described as packets of energy called photons.
What is the relation between amount of energy in Electromagnetic Radiation and the Wavelength?
The amount of energy in electromagnetic radiation is inversely proportional to its wavelength
- the shorter the wavelength, the greater the energy
What happens when Light energy is absorbed by molecules?
When a molecule acquires the energy of the photon, it is raised from a ground state (with lower energy) to an excited state with higher energy.
Is Green Light absorbed?
No, Chlorophyll A and B don’t absorb green light
- leaves are green because it is reflected
What happens when a Beam of White light falls on a pigment?
When a bean of white light falls on a pigment , certain wavelengths are absorbed.
What happens to the remaining Wavelength that are not absorbed?
The remaining wavelength are scattered or transmitted and make the pigment appear to us as colored.
What is the Structure of Chlorophyll?
Chlorophyll’s structure allows it to absorb energy from light
- consists of a complex ring structure and a hydrocarbon tail
- The hydrocarbon tail anchors the chlorophyll in the hydrophobic region of a membrane in the chloroplast thylakoid
What is a Photosystem?
A photosystem is a complex of proteins and pigments in the thylakoid membrane.
- Antenna system
- Reaction center
How do the Antenna System and Reaction Center work together?
Pigments in the antenna system absorb light energy and transfer it to chlorophyll a in the reaction center.
What is the Movement of Electrons in a Photosystem?
Electrons from chlorophylls in the reaction center are transferred to an electron acceptor
Electrons are transported through the thylakoid membrane
What role does Water have in the Reaction Centre?
Water molecules are split to provide electrons for chlorophylls in the reaction center
Where are Protons transferred to?
Transferred from stroma to the interior of thylakoids during electron transport
- Moves from [high] to [low]
What is the role of Movement of Electrons?
The movement of electrons in thylakoid membrane powers the production of both ATP and NADPH.
How is the Energy of Electrons boosted in Photosystem 1?
Electrons energy is boosted in photosystem I and transferred to NADP+
- adds energy to electrons from PSII
- energy of light increase energy of electrons
What are the Products of the Light Reaction?
The light reactions of photosynthesis lead to the production of:
- ATP
- NADPH
- O2
What is Chemiosmosis?
Both mitochondria and chloroplasts use chemiosmosis to generate ATP
- The movement of protons through special channels to produce a proton gradient
- Membrane-based mechanisms use the energy provided by food or sunlight to generate ATP
What are the Similarities of Chemiosmosis in Mitochondria and Chloroplasts?
- Before ATP produced, a chemical gradient of H+ is present
- Complex collection of proteins uses electrons to pump H+ from one side to another
- Same ATP synthase used to create ATP
- Membrane-based mechanisms
What are the differences of Chemiosmosis in Mitochondria and Chloroplasts?
Mitochondria:
1. Electron from NADH
2. H+ pump: matrix to intermembrane space
3. 1/2 O2 + 2 H+ 2e -> H2O
4. O2 is oxidizing reagent (becomes reduced)
Chloroplast:
1. Electron from H2O
2. H+ pump: Stroma -> Thylakoid space
3. H2O -> 2 H+ + 2e + 1/2 O2
4. Water is Oxidized
How is ATP synthesized?
ATP is synthesized using chemical gradient of protons
- Photosynthesis and oxidative phosphorylation = ETC + chemiosmosis
Chloroplast:
- Uses energy from sun to generate H+ gradient
Mitochondria:
- Uses energy from oxidation of food to generate H+ gradient
What is the First Stage of Photosynthesis?
a series of photosynthetic electron-transfer reactions produce ATP and NADPH
in the process, electrons are extracted from water and oxygen is released as a by-product.
What is the Second Stage of Photosynthesis?
carbon dioxide is assimilated (fixed) to produce sugars and a variety of other organic molecules.
What does Carbon Fixation use?
Carbon fixation uses ATP and NADPH to convert CO2 into sugar
What does Carbon Fixation involve?
Carbon fixation involves the formation of a covalent bond that attaches CO2 to ribulose 1,5-bisphosphate.
- The carbon-fixation cycle consumes ATP and NADPH to form glyceraldehyde 3-phosphate.
What does the production of 1 glyceraldehyde 3-phosphate require?
Production of 1 glyceraldehyde 3-phosphate requires 3 CO2, 9ATP and 6NADPH
What are the Three Stages of Carbon Fixation (Calvin) Cycle?
- Carbon fixation stage
- reduction + sugar production
- Regeneration and ribulose 1-5 bisphosphate
What are the Products of Calvin Cycle used for?
The products of Calvin cycle are used in other metabolic pathways
- Some glyceraldehyde 3-phosphate (G3P) enters glycolysis and is converted into pyruvate (in mito)
- Some glyceraldehyde 3-phosphate (G3P) enters gluconeogenesis to form glucose (in chloro)
How does Light stimulate the Calvin Cycle?
Light-induced pH changes in the stroma activate some Calvin cycle enzymes.
Light-induced electron transport reduces disulfide bridges in four of the Calvin cycle enzymes, thereby activating them.
What do Corn, Nuts, and Peas all contain?
Corn, nuts, and peas all contain rich stores of starch and fats
- Some plant seeds serve as important foods for humans.
- These stored starch and fats provide the plant embryo in the seed with energy and building blocks for biosynthesis.
What are Enzymes?
Enzymes are biological catalysts.
- Nearly all of them are proteins.
What is the Classification of Enzymes based on?
- classified based on the type of biochemical reaction they catalyze
- The name of the class describes the type of reaction they catalyze.
- The suffix –ase is commonly used to indicate that a molecule is an enzyme
