Biology - Ch 6
What are the products of each turn of the citric acid cycle?
1 ATP, 3NADH, 1FADH2
6.11 Identify the total possible yield of ATP molecules per glucose. Explain why the number of ATP molecules cannot be stated exactly
32 Depends on: -if NADH passes its electrons to NAD or FAD, which adds electrons farther along the electron transport chain, therefore contributing less to the H+ gradient and generating less ATP -if enough O2 is present
Oxaloacetate
A four-carbon molecule that binds with the two-carbon acetyl unit of acetyl-CoA to form citric acid in the first step of the Krebs cycle.
6.13 Describe the evolutionary history of glycolysis.
Ancient prokaryotes are thought to have used glycolysis to make ATP long before oxygen was present in Earth's atmosphere The oldest-known fossils of bacteria date back more than 3.5 billion years, O2 wasn't present in Earth's atmosphere until 2.7 billion years ago
6.2 Explain how breathing and cellular respiration are related.
Breathing is an exchange of gasses, CO2 goes out, O2 comes in. The O2 is then used in cellular respiration to produce ADP to power cellular work. CO2 is a waste product of cellular respiration which is expelled from the body through breathing
6.0: Explain why brown fat is important to small mammals, including newborn humans.
Brown fat is useful for newborns (who lack the ability to shiver to stay warm) because the cellular respiration of brown fat cells are "short-circuited" to generate heat rather than ATP
6.3 Provide the overall chemical equation for cellular respiration. Compare the efficiency of this process in cells with the efficiency of a gasoline automobile engine.
C6H12O6 + 6O2 ---> 6CO2 + 6H20 + ATP + Heat Cellular respiration captures 34% of the available energy from Glucose, which is more efficient than a car, which captures 25% of gas energy into mechanical energy
6.14 Explain how carbohydrates, fats, and proteins are used as fuel for cellular respiration. Explain why a gram of fat yields more ATP than a gram of starch or protein.
Carbs -> sugars -> glycolysis -> atp Proteins -> amino acids -> glycolysis/acetyl coA/citric acid cycle/oxidative phosphorylation -> atp Fats -> glycerol to glycolysis OR fatty acids to acetyl coA -> atp fats yields more ATP than starch or protein because they contain many hydrogen atoms and thus many energy-rich electrons.
6.5 Describe the general roles of dehydrogenase, NAD+, the electron transport chain, and oxygen in cellular respiration.
Dehydrogenase: an enzyme that strips two hydrogen atoms from the organic fuel molecule and transfers two electrons and one proton to its coenzyme NAD+, reducing it to NADH. NAD+: nicotinamide adenine dinucleotide. a coenzyme that gains 2 elections and one proton, reduces to NADH. Electron Transport Chain: carrier molecules upon which elections are passed, releasing energy on each step through a series of redox reactions Oxygen: gains H, is reduced to H20
6.5 Explain how the energy in a glucose molecule is released during cellular respiration
Electrons are transferred from glucose or other organic fuels to oxygen, releasing energy
What happens in stage one of cellular respiration? Where does it happen?
Glycolysis - Glucose is broken down into 2 molecules of pyruvate. A small amount of ATP is created Substrate level phosphorylation occurs - an enzyme transfers a phosphate from a substrate group to ADP, creating ATP Occurs in the cytosol
6.7-6.11 List the cellular regions where glycolysis, the citric acid cycle, and oxidative phosphorylation occur. Note whether substrate-level phosphorylation or chemiosmosis occur.
Glycolysis: Cytosol, substrate-level phosphorylation happens Citric Acid Cycle: Mitochondria, substrate-level phosphorylation happens Oxidative Phosphorylation: Mitochondria, chemiosmosis happens
6.4 Define a kilocalorie (kcal) and relate it to a food calorie
Kcal: the quantity of heat required to raise the temperature of 1 kilogram (kg) of water by 1°C Food Calories are kilocalories
6.10 Explain how brown fat is specialized for heat production and when brown fat is most active. Describe the evidence that suggests that brown fat is present and functioning in many adult humans.
Mitochondria in brown fat can burn fuel and produce heat without making ATP. Ion channels spanning the inner mitochondrial membrane allow H+ to flow freely across the membrane and dissipate the H+ gradient that the electron transport chain produced, which does not allow ATP synthase to make ATP. · Until recently, brown fat in humans was thought to disappear after infancy. Recent research indicates that brown fat may be present in most people, and, when activated by cold, the brown fat of lean individuals is more active (burns more calories)
During electron transport, energy from _____ is used to pump hydrogen ions into the _____.
NADH and FADH2 ; Intermembrane Space
Describe the relationship between NAD+ and NADH
NADH delivers electrons to the electron transport chain in oxidative phosphorylation and becomes oxidized to NAD+.
6.15 Explain how nutrients are used in biosynthesis.
Organic molecules from food provide raw materials for biosynthesis. Cells use intermediates from cellular respiration and ATP for biosynthesis of other organic molecules. Metabolic pathways are often regulated by feedback inhibition.
What happens in stage three of cellular respiration? Where does it happen?
Oxidative phosphorylation - NADH and a related electron carrier FADH2 shuttle electrons to electron transport chains in the inner mitochondrial membrane. Most of cellular respirations ADP is created here via chemiosmosis, using potential energy from concentrated H ions on the electron chain. H20 is a byproduct
6.1 Compare the processes and locations of photosynthesis and cellular respiration. Explain why it is accurate to say that life on Earth is solar powered.
Photosynthesis happens in the chloroplasts of plant cells while cellular respiration occurs in the mitochondria of plants and animal cells. It is accurate to say that life on Earth is solar powered because sunlight powers photosynthesis, and the products of which are then used to create organic molecules, which fuel cellular respiration, which make chemical energy available to all living cells to do work
What happens in stage two of cellular respiration? Where does it happen?
Pyruvate oxidation and the citric acid cycle complete the breakdown of glucose to carbon dioxide. A small amount of ATP is created Occurs in the mitochondria
6.6-6.11 Compare the reactants, products, and energy yield of the three stages of cellular respiration.
Reactants 1 Glucose (1 6 carbon molecule) & 2NAD 2 Pyruvate 3 electrons from NADH & FADH2, O2, H Products 1 Pyruvate (2 3 carbon molecules) & 2NADH 2 acetyl CoA, CO2, and NADH 3 H Energy Yield 1 2 ATPs (small amount) 2 Small amount of ATP 3 Lots of ATP
6.5 Explain how redox reactions are used in cellular respiration
Redox = Oxidation Reduction Reaction OIL RIG: Oxidation is Loss, Reduction is Gain Glucose (C6H1206) loses hydrogen atoms as it is oxidized to CO2; simultaneously, O2 gains hydrogen atoms as it is reduced to H2O.
6.4 Explain how the human body uses its daily supply of ATP.
The brain uses about 20% of available energy. Brain + life sustaining activity = 75% of available energy : this is your basal metabolic rate Rest is used for voluntary activities
6.12 Compare the reactants, products, and energy yield of alcohol fermentation and lactic acid fermentation. Distinguish between obligate anaerobes and facultative anaerobes.
Under anaerobic conditions, muscle cells, yeasts, and certain bacteria produce ATP by glycolysis. NAO+ is recycled from NAOH as pyruvate is reduced to lactate (lactic acid fermentation) or alcohol and CO2 (alcohol fermentation). Both make 2 ATP Obligate anaerobes are prokaryotes that live in stagnant ponds and deep in the soil that require anaerobic conditions and are poisoned by oxygen (ex. wine/beer yeasts) Facultative anaerobes make ATP either by fermentation or by oxidative phosphorylation, depending on whether 02 is available (ex. muscle cells)
Describe what happens in each area of the mitochondria during cellular respiration: inner mitochondrial membrane, intermembrane space, mitochondrial matrix
inner mitochondrial membrane: Electrons are passed from carrier to carrier intermembrane space: High concentration of H+ ions here will drive chemiosmosis. mitochondrial matrix: Oxygen accepts two electrons and picks up two hydrogen ions (H+), forming water.
The proximate (immediate) source of energy for oxidative phosphorylation is _____.
kinetic energy that is released as hydrogen ions diffuse down their concentration gradient
Some human cells, such as nerve cells, are restricted to aerobic respiration to recycle NADH and FADH2. If these cells are deprived of oxygen, then __________.
oxidative phosphorylation would come to a halt because there wouldn't be any oxygen to serve as an electron acceptor at the transport chain