AP Review Chapters 9-12

Fast Facts Metabolic pathways that release energy are called catabolic pathways - fermentation and cellular respiration Cellular respiration occurs in the mitochondria C6H12O6 + 6O2  6CO2 + 6H2O + Energy

Fast Facts Redox reactions release energy when electrons move closer to electronegative atoms the relocation of electrons releases the energy stored in food molecules, and this energy is used to synthesize ATP - the loss of e- from one substance is called oxidation - the addition of e- to another substance is called reduction

Fast Facts Respiration consists of three stages: - glycolysis, the Krebs cycle, electron transport chain (ETC) Glycolysis breaks down 1 glucose into 2 molecules of pyruvate - occurs in the cytosol Krebs cycle breaks down pyruvate into CO2 - occurs in the mitochondrial matrix

Fast Facts ETC accepts electrons from the breakdown products of the first 2 stages - the energy released at each step of the chain is used to make ATP (oxidative phosphorylation); through redox rxns. oxidative phosphorylation accounts for 90% of generated ATP

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Fast Facts Glycolysis means “splitting of sugar” - glucose (6C) 2 pyruvate (3C) Net energy yield: 2 ATP and 2 NADH If O2 is present, energy stored in NADH can be converted to ATP

Fast Facts Upon entering the mitochondrion, each pyruvate is first converted to a molecule of acetyl CoA (2C) - another NAD+ is reduced to NADH

Fast Facts Acetyl CoA will enter the Krebs cycle for further oxidation - Acetyl CoA (2C) enters, 2 CO2 (1C) leave, 3 NAD+  3 NADH, 1 FAD  1 FADH2, 1 ADP  1 ATP

Fast Facts Cristae: inner membrane folding of the mitochondria - increases surface area for more ETC’s Inside the inner membrane are enzymes called ATP synthase. - makes ATP from ADP and a phosphate ATP synthase uses energy from the ion gradient to ATP synthesis. - proton gradient

Fast Facts The ETC is an energy converter that uses the exergonic flow of e- to pump H+ ions across the membrane - from the matrix to the inner membrane space.

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Fast Facts Alcohol fermentation: pyruvate  ethanol - CO2 is released to recycle NAD+ - 2 step process to regenerate NAD+ Lactic acid fermentation: pyruvate  lactic acid - lactate is carried away by blood to the liver; lactate is converted back to pyruvate by liver cells

Sample Questions Membranes are important structural features of cells. (a) Describe how membrane structure is related to the transport of materials across a membrane. (b) Describe the role of membranes in the synthesis of ATP in cellular respiration.

Fast Facts Chloroplasts are the site of photosynthesis in plants All green parts of plants have chloroplasts - color is from chlorophyll, the green pigment in the chloroplasts - CO2 enters/O2 leaves the leaf through pores called stomata - water is absorbed through the roots 6CO2+6H2O+lightC6H12O6+6O2

Fast Facts Photosynthesis is made of two processes, each containing several steps 1) Light reaction (AKA light harvesting reaction, light dependent reaction) 2) Calvin cycle (AKA dark reaction, carbon fixation reaction)

Fast Facts The light rxn. converts solar energy to chemical energy; occurs in the thylokoid membrane - light absorbed drives a transfer of e- and hydrogen to an acceptor, NADP+ - NADP+ is reduced to NADPH - ATP is generated from ADP through photophosphorylation

Fast Facts The Calvin cycle stores the chemical energy in the form of sugar; occurs in the stroma - CO2 is incorporated w/ other molecules in the chloroplast through carbon fixation - fixed carbon is reduced to carbohydrates

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Fast Facts In the chloroplasts light is absorbed mainly by chlorophyll a. - blue and red light is primarily absorbed - green is the least absorbent color Chlorophyll b absorbs light at slightly different wavelengths

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Fast Facts Chloroplasts and mitochondria both generate ATP through chemiosmosis - both ETC’s pump protons across the membrane during the redox rxns. (transforms redox energy into proton motive force) - both use ATP synthase to couple diffusion to phosphorylation

Fast Facts Differences between oxidative phosphorylation and photophosphorylaton - in mitochondria, high energy e- are from food - in chlorplasts, photosystems capture light energy to drive e- transfer

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Fast Facts Calvin Cycle - uses ATP and NADPH to incorporate CO2 into sugar (does not make glucose but a 3 carbon sugar called G3)

Fast Facts Plants have adapted by developing C4 photosynthesis and CAM C4 plants preface the Calvin cycle w/ an alternate mode of carbon fixation - ex. Sugarcane, corn, grasses - form a 4-carbon compound as its first product

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Fast Facts CAM plants open their stomata at night, but keep them closed during the day - found in succulent plants - at night the CO2 is incorporated into other organic acids; this mode of carbon fixation is called crassulacean acid metabolism (CAM)

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Sample Questions Describe the biochemical pathways of the light dependent and carbon fixation reactions in photosynthesis

Sample Questions Compare and contrast C4 and CAM photosynthesis

Fast Facts Cell division functions in reproduction, growth, and repair Cell Division distributes identical sets of chromosomes to daughter cells A cell’s genetic material is called its genome - prokaryote = single long DNA strand - eukaryote = number of DNA molecules

Fast Facts Each duplicated chromosome has 2 sister chromatids. - each contains identical copies of the chromosome’s DNA molecule - they are connected together at the centromere

Fast Facts The mitotic phase alternates with interphase in the cell cycle The mitotic (M) phase (mitosis and cytokenesis) is the shortest part of the cell cycle. Interphase accounts for about 90% of the cell cycle.

Fast Facts - Interphase can be divided into subphases G1 (first gap), S (synthesis), and G2 (second gap)

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Fast Facts Cytokenesis divides the cytoplasm - in animals, cytokenesis occurs by the formation of a cleavage furrow - in plants there is a cleavage cannot occur because of the cell wall; vesicles will move to the center of the cell to form the cell plate.

Fast Facts The discovery of growth factors has led us to understand density-dependent inhibition of cell division Most animal cells also exhibit anchorage dependence - to divide, the cell must be attached to a substratum (ex. inside of a culture jar or extracellular matrix of a tissue)

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Sample Questions Discuss the process of cell division in animals. Include a description of mitosis and cytokinesis, and of the other phases of the cell cycle. Do not include meiosis.