Exam 1 for ib 150

Explain why four of life's characteristics are endergonic processes.

(Grow, reproduce, homeostasis, and react to the environment) They all require energy to occur, specifically they need ATP

Open circulatory systems

(evolved in insects, mollusks and other invertebrates) Blood is pumped by a heart into the body cavities, where tissues are surrounded by the blood. The resulting blood flow is sluggish Compared to other species, mammalian respiration is highly efficient; there is a very large surface area within the lungs which is maximized by the bubble like structure of the alveoli. The lungs also benefit from very thin membranes between the moist layer within the alveoli and the blood. The blood supply to the lungs is very great.

Use oxygen concentration of blood to predict location on blood with respect to systemic or pulmonary capillary beds

-Blood leaving the lungs has a Po2 of about 100 mm HG, while at rest the muscles and other tissues have a Po2 of about 40 mm Hg. -This partial pressure difference creates diffusion gradient that unloads O2 from hemoglobin to the tissues. -If saturation of hemoglobin is 100 percent, it means that every possible binding site in hemoglobin contains an oxygen molecule

Compare and contrast the function of hemoglobin and myoglobin and explain how the 2 pigments facilitate efficient movement of oxygen from the blood into muscle tissue.

-Both hemoglobin and myoglobin can bind to oxygen. -Hemoglobin can bind to four and myoglobin to one oxygen molecule. -Myoglobin does not dissociate as easily from oxygen as hemoglobin. -Myoglobin is located in the muscle tissue and only releases its oxygen. in hypoxic situations.

Differentiate and relate the roles of glucose and ATP in cellular respiration

ATP has a very short shelf life & your body needs ~20lbs of ATP each day in order to carry out the necessary functions to stay alive glucose can be stored for longer

Explain how organisms can drive endergonic reactions via energetically coupled reactions

According to the second law of thermodynamics the universe is moving towards a state of greater disorder (aka exergonic reactions produce disorder as they release heat). The four main characteristics of life as well as most of life's processes are endergonic which means that they must be coupled/combined with strong exergonic reactions in order to satisfy the 2nd law. (Basically- Use the energy released from exergonic reactions to drive endergonic reactions) (ATP broken down and energy that was broken down is used for other endergonic substances)

Be able to draw a graph that illustrates activation energy in a graph of the time course of a chemical reaction

Activation energy results from unstable transition states; energy associated with the breaking of covalent bonds

Justify why most life on Earth uses aerobic cellular respiration, instead of anaerobic metabolic processes.

Aerobic respiration is significantly more efficient (~36 ATP) compared to (~2 ATP)

Justify why some organisms would use aerobic cellular respiration and others would use anaerobic metabolic processes (either anaerobic cellular respiration or fermentation)

Aerobic respiration is the most efficient process but if oxygen is not available an organism may need to switch to a less efficient process. Facultative anaerobes are organisms that can switch between fermentation and cellular respiration. Some organisms live in environments without oxygen (i.e. bacteria in geysers) and therefore, must use another process.

When provided with equations for the surface area and volume of a shape, use them to explain why the SA:V of a small shape is greater than that of the same shape at a larger size

As cell size or body size increases 1. SA increases and volume increases 2. Volume increases ever faster than surface area 3. Therefore, SA:V ratio decreases Given the same shape, the surface area increases slower than volume since cubic a number is much bigger than quadratic.

Write the overall equation for Cellular Respiration

C6H12O6 + 6 O2 = 6 CO2 + 6 H2O + Heat (685 kcal)

Be able to use these terms in context: Catalyst, enzyme, active site

Catalyst- A substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change Enzyme- A protein produced by a living organism that acts as a catalyst to bring about a specific biochemical reaction Active Site- A region on an enzyme that binds to a protein or other substance during a reaction

Describe the role of cellular respiration in the transfer of energy from glucose to work done in the cell.

Cellular respiration is the exergonic reaction which produces ATP from the breakdown of glucose. The ATP is then used to work. If ATP is the cash then glucose is the piggy bank. Cellular respiration reconstitutes all the ATP needed and glycogen the bank account. Glycogen is a polymer of glucose stored in liver and muscle cells. Cellular respiration is making the withdrawal.

Define diffusion vs. Osmosis

Diffusion- Is the net passive movement of particles (atoms, ions, or molecules) from a region in which they are in higher concentration to regions of lower concentration. It continues until the concentration of substances is uniform throughout. Osmosis- Is the movement of water molecules through a selectively permeable membrane from higher water concentration to a lower water concentration - or - down a concentration gradient.

Understand the net flow of molecules due to osmosis is a result of the rates of movement of particles in both directions, NOT as a result of an inherent preference or force moving these molecules in one direction or the other.

Equilibrium is trying to be reached (equal quantities of particles on either side of the membrane) which is achieved through the direction of flow of water.

Define exergonic and endergonic reactions

Exergonic- a reaction where energy is released. Because the reactants lose energy (G decreases), Gibbs free energy (ΔG) is negative under constant temperature and pressure. These reactions usually do not require energy to proceed, and therefore occur spontaneously. Endergonic- is a reaction that requires energy to be driven. ... The activation energy for the reaction is typically larger than the overall energy of the exergonic reaction, and do not occur spontaneously

Determine whether a change of a system increases or decreases in enthalpy (ΔH) and entropy (ΔS) over the course of the reaction.

Exothermic: Reactants> product's energy ‡ enthalpy = negative Endothermic: Reactants< product's energy ‡ enthalpy = positive Entropy: Disorder (ΔS) When products of a chemical reaction become less ordered than the reactant molecules entropy increases and (ΔS) is positive

Relate the shape of the sigmoidal oxygen dissociation curve to the process of facilitation as caused by changes in the shape (R vs. T state) of hemoglobin affect its oxygen affinity.

Facilitation: Reality--> Oxygen is bound to heme group making it easier for other oxygen molecules to bind (vice verse) R-State: (Relaxed state) High O2 binding affinity T-State: (Tense state) Low O2 binding affinity

Distinguish between facultative and obligate anaerobic organisms.

Facultative anaerobes- Are organisms that can switch between fermentation and cellular respiration Obligate anaerobes- Complete absence of oxygen

Explain why raising temperature helps overcome the activation energy of a chemical reaction.

Reactants will move faster and collide more frequently. Increasing the temperature gives the particles more kinetic energy which helps them reach the transition state.

Explain how adding catalysts helps overcome the activation energy of a chemical reactions

Reactions occur when reactants have enough kinetic energy to reach the transition state. Reaction rates depend on both the kinetic energy of the reactants and the activation energy of the particular reaction. Interactions with amino acid r- groups at the enzyme active site stabilize the transition state and thus lower the activation energy required for the reaction to proceed.

Trace the flow of energy from chemical potential energy in C-H bonds of glucose to ATP produced

Solar energy is used to create the C-H bonds in glucose. When glucose is broken down in cellular respiration the energy in the bonds is used to phosphorylate ADP to ATP through the final stages of the ETC in which a hydrogen ion gradient is formed and they pass through the protein ATP synthase. (Because it does)

Be able to identify the most common sources of chemical potential energy

This chemical potential energy is found in chemical bonds in the food that we consume. The food is then broken down and used to produce ATP.

Use surface area:volume ratio to explain the relationship between respiratory surface area and the body size and respiratory anatomy of animals

Volume--> is proportional to length3 and increases faster with body size to surface area. Surface area--> is proportional to length 2 and when low limits diffusion of molecules and ions across surface.

Mammals have a sealed thoracic cavity

Which is sealed by the diaphragm. Normally, the diaphragm's relaxed position recoils (decreasing the thoracic volume) whereas in the contracted position it is pulled downwards (increasing the thoracic volume). Contraction of the intercostal muscles lifts the rib cage, thus aiding in increasing the thoracic volume. Relaxation of the diaphragm compresses the lungs, effectively decreasing their volume while increasing the pressure inside them. The intercostal muscles simultaneously relax, further decreasing the volume of the lungs. This increased pressure forces air out of the lungs. Conversely, contraction of the diaphragm increases the volume of the (partially empty) lungs, decreasing the pressure inside, which creates a partial vacuum. Environmental air then follows its pressure gradient down to fill the lungs. The vertebrate cardiovascular system includes a heart, which is a muscular pump that contracts to propel blood out to the body through arteries, and a series of blood vessels.

Relate the role of respiratory pigments in blood to variables in Fick's Law

-Hemoglobin- Maintains high oxygen concentration gradient during uptake in lungs1. -Hemoglobin absorbs oxygen from plasma, reducing plasma oxygen concentration. -Hemoglobin releases Co2, which decreases oxygen concentration in blood. -Hemoglobin releases oxygen, increasing the potential for oxygen uptake by plasma. -P2(high)-P1(low) -Myoglobin (muscle pigment) has a hyperbolic oxygen dissociation curve- it shows no facilitation -Platelets are cell fragments that act to minimize blood loss from ruptures blood vessels. -They do so my releasing material that helps form the blockages know as clots(d)White blood cells(i)Are part of the immune system. They fight infections -White blood cells -Transport oxygen from the lungs to tissues throughout the body. They also play a role in transporting carbon dioxide from tissues to the lungs.In humans, red blood cells make up 99.9 percent of the forms elements

Explain how the affinity of hemoglobin changes with oxygen and CO2 concentration in its environment (Bohr effect)

-There is a low saturation of oxygen when partial pressure is low (corresponds to environment of the tissue, when oxygen is released) -There is a high saturation of oxygen when partial pressure is high (corresponds to environment of the alveoli, when oxygen is taken up) -Cells with increased metabolism (e.g. hypoxic tissue) release greater amounts of carbon dioxide into the blood. -Carbon dioxide lowers the pH of the blood (via its conversion into carbonic acid) which causes hemoglobin to release its oxygen. -This is known as the Bohr effect- a decrease in pH shifts the oxygen dissociation curve to the right in tissues. -Hence more oxygen is released at the same partial pressure of oxygen, ensuring respiring tissues have enough oxygen when their need is greatest.

List the five characteristics all organisms on Earth share

1. Grow 2. Reproduce 3. Homeostasis 4. React to environment 5. Evolve

Define the First and Second Law of Thermodynamics

1st: Energy cannot be destroyed but only transferred and transformed 2nd: In any cyclic process the entropy will either increase or remain the same.

Use the Second Law of Thermodynamics to predict whether a process is exergonic or endergonic and thus will proceed spontaneously or not by qualitatively applying the equation ΔG = ΔH - T*ΔS.

2nd Law of Thermodynamics: Total entropy always increases is an isolated system. To determine whether a chemical reaction is spontaneous, it's necessary to assess the combined contributions of changes in heat and disorder (Gibbs free energy change ΔG) Free energy change in a reaction is equal to the change in enthalpy minus the change in entropy multiplied by the temperature. Chemical reactions are spontaneous when ΔG is less than zero (exergonic= heat is released which creates disorder). When ΔG is equal to zero reactions are at equilibrium. Spontaneous chemical reactions run in the direction that lowers the free energy of the system. Exergonic reactions are spontaneous and release energy. Endergonic reactions are non-spontaneous and require an input of energy to proceed.

Predict (in a general sense) changes in the rate of diffusion given changes in the various parameters of Fick's Law of Diffusion

Fick's Law of Diffusion states: "The rate of transfer of a gas through a sheet of tissue is proportional to the tissue area and the difference in gas partial pressure between the two sides and inversely proportional to the tissue thickness." Doubling the length of membrane will increase diffusion the most. So the area increases diffusion the most. You want a thinner membrane and the smaller concentration difference the quicker the diffusion. k- Diffusion coefficient (depends on solubility of gas and temperature) = Permeability P2-P1- Difference in concentration on both sides A- Area for exchange D- Thickness of barrier to cross Q- KA(P2-P1)/D As area for exchange increases, overall rate of diffusion gets higher; when thickness of barrier to cross gets thicker, the overall rate of diffusion is lower. If D gets bigger then diffusion rate decreases; if the variables increase then rate increases

Identify in which steps of cellular respiration ATP is produced, and which step is responsible for the vast bulk of ATP production during cellular respiration.

Glycolysis: 2 ATP Citric Acid Cycle: 2 AtP ETC & Oxidative Phosphorylation: 34-36 ATP

Identify the locations within a eukaryotic cell where each of the major reaction pathways of cellular respiration takes place

Glycolysis: Cytoplasm/cytosol Pyruvate Processing: Outer membrane of mitochondria Citric Acid Cycle: Mitochondria matrix ETC & Oxidative Phosphorylation: Inner Mitochondria matrix

List the four major reactions of Cellular Respiration and (separately) the inputs and outputs of each.

Glycolysis: Glucose + 2 ATP (ADP) + NAD+ = Pyruvate + 4 ATP + NADH Link Reaction/Pyruvate processing: Pyruvate + CoEnzyme A + NAD+ = Acetyl CoA + NADH + CO2 Citric Acid Cycle/Krebs Cycle: Acetyl CoA + NAD+ + FAD = CO2 + NADH + FADH2 Electron Transport Chain & Oxidative Phosphorylation: NADH + FADH2 + O2 + ADP = H2O + ATP + NAD+

Use the concepts of energetically-coupled reactions to explain how ATP does work in the cell via substrate-level phosphorylation, and classify the sub-reactions during phosphorylation as either endergonic or exergonic

In the first reaction, a phosphate group is transferred from ATP to glucose, forming a phosphorylated glucose intermediate (glucose-P). This is an energetically favorable (energy-releasing) reaction because ATP is so unstable, i.e., really "wants" to lose its phosphate group. In the second reaction, the glucose-P intermediate reacts with fructose to form sucrose. Because glucose-P is relatively unstable (thanks to its attached phosphate group), this reaction also releases energy and is spontaneous.

Identify and contrast the features of the respiratory and circulatory systems of insects and mammals that allow mammals, but not insects, to attain large body sizes.

Instead insects have a hard exoskeleton which contains valve like openings called spiracles. Air flow is regulated by small muscles that operate flap-like valves within each spiracle which contract to close the spiracle, or relax to open it. Oxygen travels along the spiracles which branch off into a network of tracheal tubes, further branching until they terminate as sacs. These sacs provide the thin, moist interface necessary for gaseous exchange. Oxygen transported this way is delivered directly to the tissues that require it, meaning it is not transported via the circulatory system. Because of this the circulatory system of insects is greatly reduced (as compared to a mammal for example). Oxygen diffuses into cell cytoplasm along a concentration gradient (having first dissolved in the moist tracheal surface); in a similar manner CO2 diffuses out of the cytoplasm to leave the insect via the spiracles. Because of the inefficiency of this method of respiration, insects must retain small body sizes. As body size or activity of an insect increases, it may be able to increase oxygen intake by manipulating the spiracle and abdominal muscles to increase ventilation. If activity decreases, due to the toxic nature of elevated oxygen levels, the insect can close spiracles to prevent increases oxygen intake.

Justify alternative hypothesis for why not all organisms possess seemingly "optimal" solutions

Mammalian lungs are not conducive (helpful) to counter-current exchange of respiratory gases. The mammalian lung ends in dead-ended sacs While this increases the surface area, it results in the need for tidal flow (the need to breath in and out.) The result: not all used air can be exhaled, and mixes with fresh inhaled air. Air sacs act as bellows that allow the lungs to have unidirectional airflow through the parabronchi where the gas exchange takes place. Highly oxygenated air (passes through the parabronchi BOTH on inhaling and exhaling)

Understand why the majority of chemical reactions an organism relies on are catalyzed with enzymes

Many reactions have too high of an activation energy for them to spontaneously occur (i.e. example to have reactions occur without raising their body temperature to dangerous levels

Predict the direction of net flow of water across a cell membrane due to osmosis given information about solute concentrations on either side of the membrane. Explain what happens to rates of movement of water molecules in both directions across the membrane at equilibrium.

Osmosis: Molecules of a solvent tend to pass through a semipermeable membrane from a more concentrated solution into a less concentrated one, thus equalizing the concentrations on each side of the membrane. If body fluids have a greater salinity than the surrounding fresh water then the net flow of water will be into the body tissue in order to reach a state of equilibrium. At equilibrium, the rate of flow is equal across the membrane. Water will move towards less solute concentration in order to create equilibrium.

Justify why the net movement of a group of molecules along a concentration gradient due to diffusion can be caused by the random movement of individual molecules

Overall pattern of net movement of molecules from high to low concentrations Due to random movement of individual molecules- NOT because of the gradient Random movement, hit membrane, random chance (no pushing) will happen until reaches equilibrium. The amount that goes in is equivalent to the amount that goes out.

Understand the role of oxygen in Cellular Respiration

Oxygen acts as the final electron acceptor. It has a high electronegativity making it an excellent final electron acceptor. As the electrons move down the electron transport chain and a proton generating ATP, the protons and electrons will combine with oxygen to form water. H+ + e- + O- = H2O

Differentiate between aerobic cellular respiration, anaerobic cellular respiration, and fermentation

Oxygen is involved and is the most efficient form of respiration with the largest ATP produced (~ATP) Anaerobic Respiration- When oxygen is not available organisms will go through anaerobic respiration. Other electron receptors are used such as (SO4)2- or (NO3)-. In some organisms glucose is replaced with H2, H2S, or CH4. Anaerobic respiration is less efficient than cellular respiration and leads to less ATP being produced. Using a different electron receptor than oxygen will lead to the production of a stronger concentration gradient. Therefore, more H+ will be pumped across the membrane at a faster rate. The stronger the concentration gradient the faster and more H+ pump leads to more ATP produced. Fermentation- C6H12O6 + 2 ADP + 2 Pi = Ethanol + CO2 + 2 ATP Glucose will be broken down into pyruvate and then NAD+ will continue to be regenerated by oxidizing NADH with CO2 being released. Electrons removed from NADH are transferred to pyruvate or a molecule derived from pyruvate instead of ETC. Lactic acid fermentation regenerates NAD+ by forming lactate. Alcohol fermentation converts pyruvate to acetaldehyde which gives off CO2. Acetaldehyde accepts electrons from NADH forming NAD+ to keep glycolysis going. 2 ATP are produced per 1 glucose.

Understand how molecules store chemical potential energy

Potential energy is stored in chemical bonds (e.g. in glucose the energy is in the C-H bonds)

Explain how counter-current flow increases the ability to absorb oxygen from the environment

The design of fish gills allows a unidirectional flow of water across the gills. The outgrowths of the gills increases surface area Counter-current flow continually maintains a favorable concentration gradient of oxygen between external water and blood, leading to near 100% blood oxygenation. Blood flows in a direction that is opposite the direction of water movement. This arrangement is called countercurrent flow, and it acts to maximize the oxygenation of the blood by increasing the concentration gradient of oxygen. Thus, countercurrent flow ensures that a concentration gradient remains between blood and water throughout the flow. The steep concentration gradient across the alveoli wall is maintained in two ways: by blood flow on one side and by air flow on the other side. This means that oxygen can diffuse down its concentration gradient from the air to the blood, while at the same time carbon dioxide can diffuse down its concentration gradient from the blood to the air. Mammalian lungs are not conductive to counter-current exchange of respiratory gases. The mammalian lung ends in dead-ended sacs. While this increases the surface area, it results in the need for tidal airflow- the need to breath in and out. The result: not all used air can be exhaled, and mixes with fresh inhaled air.

Explain why the first four are required for life

The first four involve the ability to do work (Grow, homeostasis, reproduce, and react to environment)

Understand the relationship between metabolic rate, anatomy, physiology, and cellular respiration

The flow of energy through an animal- Its bioenergetics- ultimately limits the animal's behavior, growth, and reproduction and determines how much food it needs. The amount of energy an animal uses in a unit of time is called its metabolic rate-the sum of all energy-requiring biochemical reactions occurring over a given time interval. In general, endotherms (warm blooded animal) have higher metabolic rates than ectotherms (cold blooded animal) Body size influences metabolic rate. The amount of energy it takes to maintain each gram of body weight is inversely related to body size. Minimal rates power the basic functions that support life, such as cell maintenance, breathing, and heartbeat. Thermoregulation is the process by which animals maintain an internal temperature within a tolerable range.

Predict what the consequences are for an organism following disruption of any of the major reaction pathways cellular respiration

The organism will be less efficient at carrying out the process of life. If it is a major disruption the organism will not be able to continue living.

Know the overall ΔG of energetically-coupled reactions. Understand what happens to the energy represented by ΔG of the overall coupled reactions

The overall ΔG of energetically coupled reactions is negative. The hydrolysis of ATP is a highly exergonic reaction with an inherently low activation energy

Understand how the ability to perform work is related to being alive

The second law of thermodynamics states that the universe is moving towards maximum disorder. The natural tendency is for matter to move towards equilibrium (because equilibrium=death). To do work is to maintain homeostasis and prevent moving towards equilibrium with its environment.

Understand that energy to sustain life is derived from chemical potential energy

The vast majority of energy is derived from chemical potential energy