Bio 107 Test 2
About this set
Created by:
kyliehassel on February 27, 2012
Description:
Lectures 11-19
Log in to favorite or report as inappropriate.
Order by
113 terms
Terms | Definitions |
|---|---|
 Metabolism | The sum of all of an organisms chemical reactions, involves metabolic pathways |
| Metabolic pathways | Catabolic pathways-release energy by breaking down complex molecules Anabolic pathways- Consume energy to build complex molecules |
| Energy | The capacity to cause change. Kinetic- energy of motion, ex. thermal energy or heat. Potential- Stored energy-chemical energy of structure |
| First law of thermodynamics | Energy cannot be created or destroyed, only changed in form. |
| Second law of thermodynamics | Entropy: a measure of disorder or randomness. Energy conversions will always increase the energy in the universe |
| First and Second Laws | The quantity of energy doesn't change The quality of energy changes Heat is random energy of the lowest quality |
| How is order obtained? | Organisms are open systems- energy and materials are exchanged with surroundings. Order can be increased in an organism if entropy increases in surroundings. |
| Free Energy | Portion of a systems energy avaliable to do work. A process is spontaneous when deltaG < 0 deltaG = G final state - G starting state DeltaG = deltaH - TdeltaS |
| Exergonic and Endergonic reactions | Exergonic-energy out. -deltaG, releases energy Endergonic- energy in, +deltaG, requires energy |
| Metabolic disequilibruim | In a closed system, reactions would reach equilibrium deltaG = 0 = DEAD Organisms are open systems Exchange energy and materials with surroundings Equilibrium is never reached |
| ATP | Energy carrier molecule Can be created in exergonic reactions Can by hydrolyzed for endergonic reactions |
| Structure of ATP | Adenine, ribose, 3 phosphate groups. "High energy" bonds Hydrolysis of ATP: deltaG -7.3 kcal/mol |
| How does ATP work? | It can be used to phosphorylate molecules Transfer of a phosphate group Phosphorylated intermediate is more reactive |
| ATP cycle | ATP is constantly used and regenerated Energy from catabolism-->ATP +H20-->Energy for cellular work |
| Enzymes | Ex: Nutra-sweet Made of phenylalanine and aspartic acid Products have a warning to people with PKU |
| PKU | Rare genetic disease, most babies are now tested for PKU at birth Patients lack the enzyme phenylalanine hydroxylase Converts phenylalanine to tyrosine |
| PKU (cont.) | Build up of phenylalanine can be toxic, can result in mental retardation, patients must limit their intake of phenylalanine *This example highlights the importance of a single enzyme for an organism.* |
| Enzymes | Catalysts that speed up reactions. Are not consumed in a reaction, and are very specific for their substrates |
| Enzyme Specificity | Due to unique protein shape- Conformation The substrate binds the active site- Results in an "induced fit |
| Activation Energy | Energy needed to start a reaction Bring reactants to transition state Enzymes lower activation energy (Ea) |
| How do enzymes lower Ea? | Bring reactants together, stress bonds to be broken, provide the proper environment, participate directly in the reaction |
| Catalytic Cycle | 1. Substrates enter active site. 2. Substrates are held in active site by weak interactions 3. Active site can lower Ea and speed up reaction 4. Substrates are converted to products 5.Products are released 6. Active site is avaliable for 2 new substrate molecules |
| Factors that effect Enzymes | Temperature, pH, Each enzyme has optimal conditions for highest activity |
| Factos that effect Enzymes | Cofactors: Assist enzymes in reactions, called coenzymes if organic Examples of cofactors: Metal ions, vitamins |
| Enzyme Regulation | Competitive inhibitors- bind active site Example: penicillin Blocks the active site of an enzyme for cell wall synthesis Noncompetitive inhibitors- bind sites other than the active site Engage in "allosteric regulation" |
| Allostertic Regulation | When a substance affects an enzyme without binding the active site Alters protein conformation Can activate or inhibit an enzyme -Cooperativity: binding of substrate to one subunit facilitates substrate binding to other subunits |
| Control of Metabolism | Feedback inhibition Product shuts down the reaction that produced it |
| Energy harvest and Recycling | Cellular respiration- Catabolic Photosynthesis-Anabolic |
| Redox Reactions | Oxidation-Loss of electrons Reduction-Gain of electrons Reductions and Oxidations happen together |
| Oxidating Agent | Accepts electrons, example: oxygen |
| Reducing Agent | Donates electrons, example: glucose |
| NAD+ | Coenzyme- From niacin Oxidizing agent- Accepts electrons Reduced to NADH- Stores energy **NADP and FAD are other important coenzymes. |
| Photosynthesis | Converts light energy to chemical energy 6 CO2 + 6 H20 + light delta C6H12O6 + 6O2 Occurs in chloroplasts |
| Leaf Anatomy | Stomata- On the surface of a leaf, pores for gas exchange Mesophyll- Tissue inside a leaf, contains chloroplasts |
| Light Energy | Electromagnetic energy- Travels in waves Wavelength- Distance between crests Visible light is important to life- 380-750 nm |
| Why are Leaves Green? | Light can be: Absorbed,Transmitted, Reflected We see what is not absorbed -Chlorophyll reflects and transmits green light. |
| Chloroplast Pigments | Chlorophyll a- Directly participates in light reactions,Blue-green Chlorophyll b- Indirectly participates in light reactions Olive-green Carotenoids- For photoprotection, Yellow and orange |
| Why do Leave turn colors? | In green leaves chlorophyll levels are high Masks presence of carotenoids In the fall chlorophyll is broken down Reveals red and orange colors |
| Photosynthesis | Converts light energy to chemical energy Pigments absorb light to capture light energy |
| **Light Reaction | Occur on thylakoid membranes Convert light energy to chemical energy to form ATP and NADPH |
| Excitation of Chlorophyll | A photon of light is absorbed An electron is moved to an orbital with more potential energy Moves from ground state to excited stateThe excited state is unstable Electron rapidly returns to ground state |
| Possible Fates | Energy is lost as heat or fluorescence Energy is transferred to another molecule |
| Photosystems | Capture excited electrons Two major parts Light-harvesting complexes Reaction center complex |
| Light-harvesting Complexes | Includes: Cluster of protein and pigment molecules Transfer energy to reaction-center complex |
| Reaction Center Complex | Includes: Pair of chlorophyll a molecules Primary electron acceptor Can transfer an electron to an electron transport chain |
| Photosystems in chloroplasts | Photosystem II (PS II) Absorbs 680 nm wavelength best Photosystem I (PS I) Absorbs 700 nm wavelength best |
| Linear Electron Flow | ATP is synthesized by chemiosmosis- A hydrogen ion gradient is used to do work Example: ATP synthesis |
| Light Reaction Overview | Light energy and water generate ATP and NADPH for Calvin cycle |
| Calvin Cycle | Occurs in stroma Uses ATP & NADPH Forms glyceraldehyde-3-phosphate (G3P) |
| Calvin Cycle Phases | Carbon fixation Reduction of sugar Regeneration of CO2 acceptor |
| Carbon Fixation Phase | CO2 is attached to RuBP Catalyzed by the enzyme rubisco Resulting 6C sugar is very unstable Splits to two 3C sugars |
| Reduction Phase | 3C sugars are phosphorylated by ATP 3C sugars are reduced by NADPH One of the 3C sugars is the output G3P |
| Regeneration Phase | Five G3P molecules are rearranged using ATP Three RuBP are reformed *1 net G3P is made for 3 CO2 entering the cycle |
| Fate of G3P | Transported to cytosol- Antiport with Pi Converted to: Glucose, Sucrose |
| C3 and C4 plants | C3 plants (rice, wheat, soybeans) Rubisco initially fixes CO2 into a 3C compound 3PG C4 plants (sugarcane, corn, grasses) Rubisco initially fixes CO2 into a 4C compound Oxaloacetate |
| Photorespiration | Occurs on hot dry days Plants close stomata Less CO2 is available for Calvin cycle Rubisco adds O2 instead of CO2 to RuBP Product will be converted to CO2 No sugar is made but ATP is used |
| C4 Plants | Do not use photorespiration extensively Adapted for high heat and sunlight Utilize bundle sheath and mesophyll cells |
| C4 Photosynthesis | Mesophyll cells Help increase CO2 in bundle sheath cells Bundle sheath cells Can utilize CO2 for Calvin cycle |
| CAM Plants | (Crassulacean acid metabolism) Water storing desert plants Succulents, cacti, pineapples Open stomata at night Fix CO2 to an organic acid Close stomata in the day Use organic acid for CO2 |
| Cellular Respiration | 3 major parts: Glycolysis* Citric acid cycle Oxidative phosphorylation |
| Glycolysis | Glucose is oxidized to pyruvate NADH and ATP are formed |
| Citric Acid Cycle | Pyruvate derivative is oxidized to CO2 NADH, FADH2, and ATP are formed |
| Oxidative Phosphorylation | Electron transport chain creates a gradient Gradient is used to form ATP |
| Glycolysis | "Sugar splitting" Two phases: Energy investment,Energy payoff Yields: 2 pyruvate, 2 ATP, 2 NADH Ten enzyme mediated steps All intermediates are phosphorylated **Occurs in the cytosol Summary: Glucose is oxidized to pyruvate NADH and ATP are formed |
| Types of Enzymes | Kinase Isomerase Dehydrogenase |
| Energy Investment | This enzyme is allosterically regulated. |
| Energy Payoff | Two G3P enter this phase for each glucose. |
| Substrate Level Phosphorylation | Occurs in glycolysis and citric acid cycle Phosphate group from an organic molecule is used to make ATP |
| Before the Citric Acid Cycle | Pyruvate enters the mitochondria by active transport Pyruvate is converted to acetyl coenzyme A Acetyl CoA |
| Citric Acid Cycle | Discovered by Hans Kreb First step yields citric acid Begins and ends with oxaloacetate Occurs in the mitochondrial matrix 8 enzyme mediated steps |
| Pyruvate oxidation and citric acid cycle big picture | Results in:4 NADH 1 FADH2 1 ATP |
| Oxidative Phosphorylation | 2 parts Electron transport chain Chemiosmosis |
| Electron Transport Chain | Occurs on the inner mitochondrial membrane Electrons are passed through the chain Energy is slowly released H+ ions are pumped across the membrane Creates a "proton motive force" |
| ETC Components | Complexes I-IV contain: Multiple proteins Prosthetic groups Mobile electron carriers- Ubiquinone (Q), Cytochrome c (Cyt c) Final electron acceptor- Oxygen (WHY WE NEED TO BREATHE) |
| NADH electrons enter complex I | Electrons pass from NADH to FMN NAD+ is oxidized FMN is reduced Electrons pass from FMN to FeS FMN is oxidized FeS is reducedFeS transfers electrons to Q Q carries electrons to complex III Electrons move through ETC Until they reach O2 |
| FADH2 electrons enter at complex II | Electrons pass from FADH2 to FAD Electrons pass from FAD to FES Electrons are transferred to Q Moved on through ETC to O2 |
| Cyanide | Inhibits cytochrome oxidase Shuts down ETC Complex IV Prevents cells from making ATP Especially effects cells that require a lot of ATP such as cardiac cells. |
| ATP Synthasase | Multiprotein complex In inner mitochondrial membrane H+ ions move through the enzyme down their gradient Activates catalytic portion that forms ATP from ADP + Pi |
| ATP Production without O2 | Anaerobic respiration Involves an ETC but does not use O2 Example: SO42- is used by some marine bacteria Fermentation Does not involve an ETC nor O2 ATP is produced by substrate level phosphorylation |
| Fermentation | Includes: Glycolysis to form 2 ATP Reactions to regenerate NAD+ Major types: Lactic Acid-Converts pyruvate to lactate Regenerates NAD+ Used in muscle cells when O2 level is low Alcohol- Converts pyruvate into ethanol Regenerates NAD+ |
| Anaerobes | Obligate Only perform fermentation or anaerobic respiration Facultative Can perform fermentation or cellular respiration |
| Control of Cellular Respiration | Allosteric regulation of phosphofructokinase* Feedback inhibition by ATP Additional regulation: Inhibition by citrate Stimulation by AMP |
| Cell Cycle | Interphase G1 S G2 (G0) M phase Mitosis Cytokinesis |
| Mitosis | Occurs in somatic cells Non-reproductive cells Replicated DNA is equally divided One of each chromosome is distributed to two nuclei |
| Chromosome Number | Total number of chromosomes in a cell Human somatic cells have 46 Diploid organisms have two sets of chromosomes In mitosis: A diploid parent cell produces two diploid daughter cells |
| Chromosomes | Chromosomes are duplicated in S phase Results in two sister chromatids Important structures: Centromere Kinetochore |
| Stages of Mitosis | Prophase Prometaphase Metaphase Anaphase A* B* Telophase |
| Mitotic Spindle | Assembles at centrosomes "Microtubule organizing centers" Also includes: Microtubules (MT) Associated proteins |
| Types of MT's | Kinetochore Overlapping Asters |
| G2 of Interphase | Nuclear envelope is present Chromosomes are not distinct Two centrosomes have been formed |
| Prophase | Chromosomes condense Centrosomes move apart Mitotic spindle begins to form |
| Prometaphase | Nuclear envelope breaks down Microtubules attach to chromosomes Mitotic spindle formed |
| Metaphase | Centrosomes are at opposite ends Chromosomes line up at metaphase plate M phase checkpoint |
| Anaphase A | Proteins holding sister chromatids together are degraded Sister chromatids move to opposite poles Kinetochore microtubules |
| Anaphase B | Spindle poles move further apart Force exerted by non-kinetochore microtubules Asters Overlapping |
| Telophase | Chromosomes arrive at spindle pole Nuclear envelope reforms Chromatin fibers decondense |
| Cytokenesis-animal | Cleavage furrow forms in center of cell Actin and myosin contract Cell is pinched in two |
| Cell plate formation- plants | Vesicles move to center to form a cell plate Cell plate fuses with plasma membrane Cell plate helps form new cell wall |
| Cell cycle control | The cell cycle is tightly regulated Cell cycle checkpoints Have required events occurred? G1, G2, M |
| Cell Cycle Control Signals | Kinases Enzymes that phosphorylate proteins Cyclins Control kinase activity |
| Maturation Promoting Factor (MPF) | MPF Cyclin-Cdk complex Helps cells pass from G2 to M Phosphorylates proteins to activate or inhibit them Example: MPF phosphorylates nuclear lamina to facilitate its breakdown |
| MPF in the cell cycle | Cdk levels remain constant Cyclin levels rise and fall MPF is only active in G2/M |
| Cancer Cells | Have escaped cell cycle control Undergo excessive division Can invade other tissues |
| Terms | Diploid(2n) Haploid (n) Sister chromatids Homologous chromosomes |
| Meiosis | Two consecutive nuclear divisions In reproductive cells Reduces chromosome number by half In human cells, from 46 to 23 Results in four unique haploid cells These cells give rise to gametes |
| Fertilization in Humans | Haploid egg and sperm fuse Each is n=23 Results in a diploid zygote Now 2n=46 Chromosome number is restored |
| Meiosis | Chromosomes replicate once in S phase Two consecutive nuclear divisions occur Meiosis I and meiosis II Stages similar to mitosis |
| Prophase 1 | Synapsis Physical pairing of homologous chromosomes Crossing Over Exchange of portions of non-sister chromatids Formation of chiasmata |
| Importance of Crossing Over | Provides genetic variation Ensures proper chromosome segregation |
| Anaphase 1 and 2 | Anaphase I: Homologous chromosome pairs separate Anaphase II: Sister chromatids separate |
| The Big Picture | Mitosis produces identical copies of parent cell For asexual reproduction For growth, renewal and repair Meiosis produces unique gametes with genetic variability For sexual reproduction |
| Sources of Genetic Variation | Crossing over Prophase I Independent assortment Metaphase I Random fertilization After meiosis and gamete formation |
| Independent Assortment | Due to random alignment of homologues during metaphase I of meiosis There are two possible orientations for each pair The number of possible alignments for a cell can be calculated: 2n For humans 223 = 8.4 million |
First Time Here?
Welcome to Quizlet, a fun, free place to study. Try these flashcards, find others to study, or make your own.