AP Biology All living systems require constant input of free energy. Metabolism and Energy

AP Biology Flow of energy through life  Life is built on chemical reactions  transforming energy from one form to another organic molecules  ATP & organic molecules sun solar energy  ATP & organic molecules

AP Biology The First Law of Thermodynamics Energy cannot be created or destroyed, only transformed. Living systems need to continually acquire and transform energy in order to remain alive. “Free energy”: The energy available in a system to do work.

AP Biology The 2 nd Law of Thermodynamics Every time energy is transformed, the entropy (“disorder”) of the universe increases. *Loss of order or free energy flow results in death.

AP Biology How do organisms maintain order?  By “Coupling Cellular Processes”  Using reactions that increase entropy (disorder) to power those that decrease entropy (make orderly) ++ energy + +

AP Biology Metabolic Reactions  Can form bonds between molecules  dehydration synthesis  synthesis  anabolic reactions  ENDERGONIC  Can break bonds between molecules  hydrolysis  digestion  catabolic reactions  EXERGONIC breaking down molecules= less organization= lower energy state building molecules= more organization= higher energy state

AP Biology Endergonic vs. exergonic reactions exergonicendergonic - energy released - digestion - energy input - synthesis -G-G  G = change in free energy = ability to do work +G+G

AP Biology Getting the reaction started…  Breaking down large molecules requires an initial input of energy  activation energy  large biomolecules are stable  must absorb energy to break bonds energy cellulose CO 2 + H 2 O + heat Can cells use heat to break the bonds?

AP Biology How Much Energy to Get Over Hump?  The amount of energy needed to destabilize the bonds of a molecule  Is our temperature adequate? Not a match! That’s too much energy to expose living cells to!

AP Biology Spontaneous?  If some reactions are “downhill”, why don’t they just happen spontaneously?  because covalent bonds are stable bonds Stable polymers don’t spontaneously digest into their monomers

AP Biology Catalysts  So what’s a cell got to do to reduce activation energy?  get help! … chemical help… ENZYMES GG Call in the ENZYMES!

AP Biology Energy needs of life  Organisms are endergonic systems  What do we need energy for?   synthesis (biomolecules)  reproduction  active transport  movement  temperature regulation

AP Biology Insufficient Free Energy Production  Individual = disease or death  Population = decline of a population  Ecosystem = decrease in complexity  Less productivity  Less energy moving through system

AP Biology 2. M ATH S KILLS : G IBBS F REE E NERGY 3.1: All living systems require constant input of free energy.

Be able to use and interpret the Gibbs Free Energy Equation to determine if a particular process will occur spontaneously or non-spontaneously. ΔG= change in free energy (- = exergonic, + = endergonic) ΔH= change in enthalpy for the reaction (- = exothermic, + = endothermic) T = kelvin temperature ΔS = change in entropy (+ = entropy increase, - = entropy decrease) What You Have To Do

Spontaneity Spontaneous reactions continue once they are initiated. Non-spontaneous reactions require continual input of energy to continue.

Using the Equation To use the equation, you’ll need to be given values. Exothermic reactions that increase entropy are always spontaneous/exergonic Endothermic reactions that decrease entropy are always non-spontaneous/endergonic. Other reactions will be spontaneous or not depending on the temperature at which they occur.

Sample Problem Determine which of the following reactions will occur spontaneously at a temperature of 298K, justify your answer mathematically: Reaction 1: A + B → AB Δ H: +245 KJ/mol Δ S: -.02 KJ / K Reaction 2: BC → B + C Δ H: -334 KJ/mol Δ S: +.12 KJ/K

AP Biology ATP Living economy  Fueling the body’s economy  eat high energy organic molecules  food = carbohydrates, lipids, proteins, nucleic acids  break them down  catabolism = digest  capture released energy in a form the cell can use  Uses an energy currency  a way to pass energy around  need a short term energy storage molecule Whoa! Hot stuff!

AP Biology ATP  Adenosine Triphosphate  modified nucleotide  nucleotide = adenine + ribose + P i  AMP  AMP + P i  ADP  ADP + P i  ATP  adding phosphates is endergonic high energy bonds How efficient! Build once, use many ways

AP Biology How does ATP store energy?  Each negative PO 4 more difficult to add  a lot of stored energy in each bond  most energy stored in 3rd P i  3rd P i is hardest group to keep bonded to molecule  Bonding of negative P i groups is unstable  P i groups “pop” off easily & release energy  Spring Loaded! P O–O– O–O– O –O–O P O–O– O–O– O –O–O P O–O– O–O– O –O–O P O–O– O–O– O –O–O P O–O– O–O– O –O–O P O–O– O–O– O –O–O P O–O– O–O– O –O–O P O–O– O–O– O –O–O Instability of its P bonds makes ATP an excellent energy donor I think he’s a bit unstable… don’t you? AMP ADPATP

AP Biology How does ATP transfer energy?  ATP  ADP  releases energy (exergonic)  Phosphorylation (adding phosphates!)  released P i can transfer to other molecules  destabilizing the other molecules  enzyme that phosphorylates = kinase P O–O– O–O– O –O–O P O–O– O–O– O –O–O P O–O– O–O– O –O–O 7.3 energy + P O–O– O–O– O –O–O ADPATP

AP Biology It’s never that simple! An example of Phosphorylation…  Building polymers from monomers  need to destabilize the monomers  phosphorylate! C H OH H HOHO C C H O H C + H2OH2O kcal/mol C H OH C H P + ATP + ADP H HOHO C + C H O H CC H P + PiPi “kinase” enzyme -7.3 kcal/mol -3.1 kcal/mol enzyme H OH C H HOHO C

AP Biology ATP / ADP cycle A working muscle recycles over 10 million ATPs per second Can’t store ATP  too reactive  transfers P i too easily  only short term energy storage  carbs & fats are long term energy storage

AP Biology What’s the point?  Cells spend a lot of time making ATP! “WHY?” For chemical, mechanical, and transport work Make ATP! That’s all I do all day. And no one even notices!

AP Biology Energy Requirements  Life requires energy to run reactions  The speed at which reactions occur is one’s metabolic rate.  Energy needs correlate to metabolism  Factors affecting energy needs: 1. Animal size 2. Activity 3. Environment Minimum metabolic rate for endotherms = BMR Minimum metabolic rate for ectotherms = SMR

AP Biology Bioenergetics of an animal

AP Biology Measuring Metabolic Rate  Find amount of heat loss or O 2 consumed or CO 2 produced

AP Biology Size Matters!  Energy needs for body mass is inversely related to body size. WHY?  More O2, respiratory rate and heart rate

AP Biology Activities to Regulate Metabolism  Torpor – state of decreased activity and metabolism to save energy when in difficult conditions  Hibernation  Estivation

AP Biology Thermoregulation  Heat regulation in mammals often involves the integumentary system: skin, hair, and nails  Adaptations that help animals thermoregulate: 1. Insulation 2. Circulatory adaptations 3. Cooling by evaporative heat loss 4. Behavioral responses 5. Adjusting metabolic heat production

AP Biology Ectotherms vs. Endotherms  Body temperature must be regulated for metabolic reactions

AP Biology Circulatory Adaptations for Thermoregulation  Vasoconstriction or Vasodilation  Counter-current heat exchange

AP Biology Other adaptations:

4. M ATH S KILLS : C OEFFICIENT Q : All living systems require constant input of free energy.

Be able to use and interpret the Coefficient Q 10 equation: t 2 = higher temperature t 1 = lower temperature k 2 = metabolic rate at higher temperature k 1 = metabolic rate at lower temperature Q 10 = the factor by which the reaction rate increases when the temperature is raised by ten degrees. What You Have To Do

Q 10 tells us how a particular process will be affected by a 10 degree change in temperature. Most biological processes have a Q 10 value between 2 and 3 What It Means

Sample Problem Data taken to determine the effect of temperature on the rate of respiration in a goldfish is given in the table below. Calculate the Q 10 value for this data. Temperature (°C)Heartbeats per minute