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Bio Study Guide
Biology Exam #2 Based on the Study Guide
Question | Answer |
---|---|
Metabolism | The totality of a cell's chemical reactions |
What are the 2 reactions metabolism can be broken down into? | Catabolic and Anabolic reactions. |
Catabolic Reactions | Break down molecules from more ordered structures to more disordered structures, and thus increase entropy |
What does catabolic reactions release? | Chemical (potential energy), and result in molecules with increased stability. |
What are catabolic reactions spontaneous? | They require no input of free energy, and because they are spontaneous they have a (-))ΔG value. |
Anabolic reactions | Build up molecules from less ordered structures to more ordered structures |
Because anabolic reactions build up molecules, what do they need? | The require an input of energy, and so have a (+))ΔG value, and are therefore endergonic. |
What is the result of anabolic reactions being nonspontaneous? | Result in molecules that are less stable and contain more chemical (potential) energy |
In order to remain alive, the metabolic reactions of a cell must do what? | Must always be moving toward equilibrium, but must also always be taking in more reactants to maintain disequilibrium in order to remain alive. |
What do enzymes do? | They lower the activation energy barrier for specific chemical reactions. |
Redox Reaction | A reaction which contains 2 essential reactants and 2 essential products. 1 of the reactants loses its electrons to the other reactant. |
Oxidized | The product that lost its electrons in a redox reaction |
Reduced | The product that gains the electron in a redox reaction |
Reducing Agent | The reactant that lost its electron |
Oxidizing Agent | The reactant that gains the electrons |
In cellular respiration, __(1)___ is the reducing agent while __(2)____ is the oxidizing agent | 1. Glucose ; 2. Oxygen |
In cellular respiration, glucose becomes oxidized resulting in what? | The product CO2 |
In cellular respiration, oxygen becomes reduced resulting in what? | The product H2O |
The overall movement of electrons in cellular respiration | Glucose to NADH (and FADH2) to the electron transport chain to oxygen |
What are the main stages in cellular respiration? | Glycolysis ; Pyruvate conversion ; Citric Acid Cycle ; Oxidative Phosphorylation |
Where does Glycolysis occur? | In the cytoplasm |
What happens in Glycolysis? | The breaking down of glucose into 2 pyruvate molecules |
What are the 2 phases Glycolysis consists of? | Energy Investment Phase and Energy Payoff Phase |
What happens in the Energy Investment Phase of Glycolysis? | Uses 2 ATP and Breaks one glucose molecule into 2 pyruvate moelcules |
What happens in the energy payoff phase of Glycolysis? | Produces 4 ATP and 2 NADH (2 ATP and 1NADH per molecule) |
What is the net production of glycolysis? | 2 Pyruvate, 2 ATP, 2 NADH |
Where does pyruvate conversion happen? | In the mitochondrial matrix |
What happens in pyruvate conversion? | Pyruvate is oxidized to acetyl CoA; Each time one conversion happens, one CoA molecule is added. Each time one pyruvate is oxidized to acetyl CoA: 1 NADH is generated and 1 CO2 is released. Remember, 2 pyruvates are produced per 1 glucose molecule |
What is another way of saying the Citric Acid Cycle? | TCA cycle ; Krebs Cycle |
Where does the Citric Acid Cycle happen? | In the mitochondria |
What happens in the Citric Acid Cycle? | Acetyl CoA combines with the last metabolite of the citric acid cycle (oxaloacetate) to form citrate. Additional reactions occur to form the last citric acid cycle metabolite again, which then again combines with a new acetyl CoA and the cycle repeats |
What is produced in the Citric Acid Cycle? | - 3 NADH and 1 FADH2 are produced per turn of the cycle; - 1 ATP is produced per turn of the cycle ; - 2 CO2 are released per turn of the cycle (The cycle turns twice for every 1 glucose of molecule) |
What are the two sections of Oxidative Phosphorylation (OXPHOS)? | Electron transport chain and chemiosmosis/ATP synthase/ ATP generation |
Where does the Electron Transport Chain (ETC) happen? | Mitochondrial matrix, IMM, IMS |
How many electron acceptors are in the ETC? | 7 : Complex 1, Complex II, Q, Complex III, Cyt C, Complex IV, and O ; Complexes I-IV are embedded in the IMM. O2 is in the matrix |
Describe the transactions between the electron acceptors in the ETC. | NADH passes electrons to Complex I; FADH2 passes electrons to Complex II; electrons get passed down to Q; Q passes electrons to Complex III; Complex III passes electrons to Cyt C; Cyt C passes electrons to Complex IV |
Overall, what happens in the ETC? | As electrons are passed from one complex to the next, H+ ions are pumped from the matrix into the IMS |
What is the result of the ETC? | Electrochemical gradient: creating a high concentration in the IMS and a low concentration of H+ in the matrix |
How is water formed in the ETC? | Complex IV passes the electrons to O2 which combines with H+ ions to form H2O in the mitochondrial matrix |
What is the most electronegative molecule in cellular respiration (from glucose, to NADH/FADH2, to ETC complexes, to Oxygen)? | Oxygen |
Why is Oxygen the final electron acceptor in the ETC? | Because it is the most electronegative molecule in cellular respiration. |
What happens if you don't breathe in oxygen? | Cellular respiration stops, you don't produce enough energy to survive, and you die. |
What is the name of the process in which H+ ions flow down their concentration gradient from the IMS through ATP synthase into the matrix? | Chemiosmosis |
What does Chemiosmosis cause? | ATP synthase to add a phosphate to ADP, forming ATP in the matrix that will be transported to the rest of the cell |
Where is ATP synthase embedded? | In the IMM |
What happens in the absence of oxygen? | OXPHOS cannot occur, and OXPHOS-derived ATP cannot be generated |
Describe what happens in fermentation? | In order to stay alive, cells rely on ATP produced by glycolysis. But they must convert NADH back to NAD+ for this to work. So, they convert pyruvate to either lactate or ethanol, which regenerates NAD+, which can re-enter glycolysis to keep producing ATP |
Stromata | Structures in leaves through which CO2 enters and O2 exits. |
Mesophyll cells | In leaves that contain chloroplasts |
What is essentially a chloroplast? | An organelle with a double-lipid bilayer |
Stroma | Fluid inside chloroplasts |
The inner membrane of a chloroplast is further organized into stacks of flattened discs called _______. | Thylakoids |
Grana | Stacks of thylakoids |
Thylakoids contain what pigment? | Chlorophyll |
What happens in Light Reactions during Photosynthesis? | The splitting of H2O into hydrogen and oxygen (oxygen is released) |
Name the products and how to get the products during Light reactions of photosynthesis,, | Using the electrons to produce NADPH and using hydrogen to generate an electrochemical gradient which will then generate ATP |
What happens during the Calvin Cycle of photosynthesis? | Consuming CO2 to produce carbohydrates |
How is the Calvin cycle able to produce carbohydrates? | using electrons in NADPH and ATP generated during Light Reactions |
What absorbs a photon of light in the light harvesting complex of Photosystem II? | Chlorophyll |
Photosystem II - What happens when chlorophyll absorbs a photon of light? | It excites an electron in chlorophyll from the ground state to the excited state |
Photosystem II - Energy is passed along several chlorophyll molecules in the __(1)__ until it excites a chlorophyll molecules in the __(2)__ | 1. light harvesting complex 2. reaction-center complex |
Photosystem II - Excited electron in reaction center complex is given to a protein in a redox reaction. H2O is then split to donate an electron back to reaction center complex chlorophyll. What does this result in? | H + ions in lumen of thylakoid and in oxygen (which will diffuse out |
Photosystem II - Electron continues to pass through a series of redox reactions, generating more H+ in the lumen of the thylakoid (thylakoid space). This electron will eventually be used to ________ | neutralize the chlorophyll in the reaction center complex of light harvesting complex I |
Photosystem I - Just like in photosystem II, what happens? | A photon excites a chlorophyll electron in the light harvesting complex. This energy is passed through several chlorophyll molecules in the light harvesting complex until it excites an electron in a chlorophyll molecules in the reaction center complex |
Photosystem I - The electron is passed through a series of redox reactions, eventually generating what? | NADPH in the chloroplast stroma. |
Photosystem I - The electron in Photosystem II is used to do what? | Neutralize the chlorophyll in photosystem I reaction center complex |
Photosystem I - ATP Generation. The H+ ions which make up an electrochemical gradient in the thylakoid space flow through ATP synthase into the chloroplast stroma, generating what? | ATP in the chloroplast stroma |
Calvin Cycle | In a series of reactions, the ATP and NADPH from Light Reactions and CO2 from the atmosphere are used to produce the carbohydrate, glyceraldehydge-3-phosphate (G3P) |
How many times does the Calvin Cycle turn to produce 1 G3P? | 3 times |
What are the 3 phases of the Calvin Cycle? | 1. Carbon Fixation 2. Reduction 3. Regeneration of RuBP |
How many hydrogen bonds go through A and T in DNA? | 2 hydrogen bonds |
How many bonds does C bond with G in DNA? | 3 hydrogen bonds |
What kind of nature is between DNA strands? | Antiparallel nature |
Semiconservative model of DNA replication | 1 parental strand separates, and each separated parental strand serves as a template for daughter strands. When finished, replicated DNA is a combination of 1 parental strand and 1 newly-synthesized daughter strand. |
Where does DNA replication begin? | At sequences called the origin of replication (ORI) |
How many ORI per circular chromosomes are in prokaryotes? | 1 |
How many ORI s per linear chromosome in eukaryotes? | Multiple |
Helicase | Unwinds and 'unzips' the double helix |
Topoisomerase | Relieves torsional strain caused by unwinding and 'unzipping' |
Single-Stranded binding Proteins | Stabilize the single-stranded DNA |
Primase | adds an RNA primer. DNA polymerase cannot begin DNA synthesis on a bare single-stranded DNA. The RNA primer is 5-10 RNA nucleotides long |
When DNA polymerase recognizes the RNA primer. what does it do? | It begins to add nucleotides completmentary to the DNA template in a 5' to 3' direction. |
In what direction is the template strand read? | 3' to 5' direction |
In what direction is the NEW DNA strand synthesized in? | 5' to 3' direction. New nucleotides are added to the 3' end of the previously added nucleotide. |
DNA polymerase can only recognize the 3' end of nucleotides, and therefore what happens? | There is a leading strand (which is synthesized INTO the replication fork) and a lagging strand (comprised of Okazaki fragments, which is synthesized AWAY FROM the replication fork |
The free nucleotides are in the form of __(1)__, and therefore contain the __(2)__ necessary for the formation of new DNA strands. | 1. nucleotide triphosphates; 2. potential energy |