Study concept map
Metabolism-is an emergent property of life that arises from orderly interaction between molecules.
Metabolic pathway- an elaborate road map of thousands of chemical reactions that begins with a specific molecule which is then altered in a series of defined steps resulting in a certain product.
Metabolism as a whole manages the material and energy resources of the cell.
Catabolic pathways- pathways that release energy by breaking down complex molecules to simpler compounds
Major pathway of catabolism is cellular respiration in which sugar glucose and other organic fuels are broken down in the presence of oxygen to carbon dioxide and water.
Anabolic pathways- in contrast consume energy to build complicated molecules from simpler ones.
Energy stored in the organic molecules becomes available to do the work of the cell
Ex- synthesis of an amino acid synthesis of a protein from amino acids
Energy is the capacity to cause change.
Kinetic energy- the relative motion of objects
Thermal energy- random movement of atoms or molecules; thermal energy can transfer from one object to another causing it to heat up.
Potential energy- the energy that matter possesses because of its location or structure.
Chemical energy- refers to the potential energy available for release in a chemical reaction
Thermodynamics- study of the energy transformations that occur in a collection of matter
Entropy- a measure of molecular disorder or randomness
First law of thermodynamics- the energy of the universe is constant: Energy can be transferred and transformed but it cannot be created or destroyed
Respiration-gas exchange between organism and its environment
Breathing the alternation of inhalation and exhalation
cellular respiration: aerobic-with oxygen anaerobic-without oxygen
C6H12O6+6O2----6CO2+6H2O+energy or One glucose molecule------36or38 ATP
Steps in cell respiration: 1Glycolysis Transition Reaction 2 Krebs Cycle 3 Electron Transport System
Glycolysis: 1 location occurs in cytoplasm specifically the cytosol of cell near mitochondria 2 Oxygen requirement-does not require oxygen
Glycolysis Reactants and Products: Reactants-1 glucose 2 NAD from ETS 2ADP +2P. Products: 2 ATP 2 pyruvic acid 2 NADH go to ETS 2H
Transition Reaction: Location-cytoplasm->mitochondria. Oxygen requirement- no oxygen required
Transition Reaction Reactants and Products
Reactants: 2 pyruvic acid 2 NAD from ETS 2 Coenzyme. Products: 2NADH-go to ETS 2 Acetyl CoA
Krebs Cycle
Location-mitochondrial matrix. Oxygen requirement- no oxygen
Reactants 2 Acetyl CoA 6 NAD from ETS 2 ADP +2P 2 FAD from ETS. Products 4 CO2 6 NADH go to ETS 2 FADH2 go to ETS 2ATP
Electron Transport system
Location-inner mitochondrial membrane. Oxygen requirement-aerobic
Reactants 10 NADH 2FADH2 O2 H ADP,P Products H2O 32 or 34 ATP NAD FAD
Oxidative Phosphorylation
1 Occurs in cristae of mitochondria 2 responsible for greatest production of ATP 3 term oxidative comes from use of oxygen as terminal electron acceptor 4 term phosphorylation comes from a molecule of ATP being phosphorylated to ATP 5 Aerobic 6 Electron carriers bring the electrons to a group of coenzymes (the electron transport chain 7 as electrons are transported down the chain energy is released 8 The energy is used to make ATP from ADP and P 9 Final acceptor of the electrons is oxygen 10 Oxygen removes the hydrogen and electrons, making water
Summary: At the completion of glycolysis and the Krebs cycle glucose has broken down into carbon dioxide which is released from the mitochondria. Oxygen and hydrogen have ben converted to water. A maximum of 36 to 38 ATP's have been produced for the cell
Fermentation
- Anaerobic reaction 2. Breakdown of glucose into two 3-carbon molecules called pyruvic acid 4Two types 1. Alcoholic 2 Lactic acid
Chloroplasts are found mainly in cells of the mesophyll the interior tissue of the leaf. Each mesophyll cell contains 30-40 chloroplasts. CO2 enters and O2 exits the leaf through microscopic pores called stomata
6 CO2 + 12 H2O+light energy-C6H12O6+6O2+6H2O
A chloroplast has an envelope of two membranes surrounding a dense fluid called the stroma
Thylakoids are connected sacs in the chloroplast that compose a third membrane system may be staked in columns called grana
Chlorophyll the pigment that gives leaves their green color resides in the thylakoid membranes
The overall chemical change during photosynthesis is the reverse of the one that occurs during cellular respiration
Photosynthesis reverses the direction of electron flow compared to respiration. Photosynthesis is a redox process in which H2O is oxidized and CO2 is reduced. Photosynthesis is an endergonic process the energy boost is provided by light
Two stages of Photo synthesis - light reaction and calvin cycle
The light reaction splits H2O release O2 Reduce the electron acceptor NAHP to NADPH Generate ATP from ADP by photophosphorylation
The Calvin cycle in the stroma forms sugar from CO2 using ATP and NADPH. The Calvin cycle begins with carbon fixation incorporating CO2 into organic molecules
Thylakoids transform light energy into the chemical energy of ATP and NADPH
Two types of pigments in chloroplasts: Chlorophyll a, the key light capturing pigment. Chlorophyll b, an accessory pigment
Accessory pigments called carotenoids may broaden the spectrum of color that drive photosynthesis
When a pigment absorbs light it goes from a ground state to an excited state
A primary electron acceptor in the reaction center accepts excited electrons and is reduced as a result
Photosystem II function first of the two
Photosystem I is best at absorbing a wavelength of 700 nm
Two possible routes for electron flow cyclic and linear.
Linear electron flow- the primary pathway involes both photosystems and produces ATP and NADPH using light energy
Eight steps in linear electron flow: 1 A photon hits a pigment in a light harvesting complex of PS II and its energy is passed among pigment molecules until it excites P680. 2 An excited electron from P680 is transferred to the primary electron acceptor 3 H2O is split by enzymes and the electron are transferred from the hydrogen atoms to P680+ thus reducing it to P680(P680+ is the strongest known biological oxidizing agent. The H+ are released into the thylakoid space. O2 is released as a by product of this reaction)
4 Each electron falls down an electron transport chain from the primary electron acceptor of PS II to PSI. Energy released by the fall drives the creation of a proton gradient across the thylakoid membrane 5 Potential energy stored in the proton gradient drives production of ATP by chemiosmosis 6. In PSI transferred light energy excites P700 which loses an electron to the primary electron acceptor (P700+ accepts an electron passed down from PSII via the electron transport chain
7 Each electron "falls" down an electron transport chain from the primary electron acceptor of PS I to the protein ferredoxin 8 NADP+ reductase catalyzes the transfer of electrons to NADP+ reducing it to NADPH(the electrons of NADP are available for the reactions of the Calvin cycle. THis process also removes an H+ from the stroma
Cyclic Electron Flow- electrons cycle back from Fd to the PS I reaction center via a plastocyanin molecule (Pc) Cyclic electron flow uses only photosystem I and produces ATP but not NADPH no oxygen is released
in choloroplasts protons are pumped into the thylakoid space and drive ATP synthesis as they diffuse back into the stroma
The Calvin cycle like the citric acid cycle regenerates its starting material after molecules enter and leave the cycle
The Calvin cycle is anabolic it builds sugar from smaller molecules by using ATP and reducing power of electrons carried NADPH
The Calvin cycle has three phases: 1 Carbon Fixation 2 Reduction 3 Regeneration of the CO2 acceptor