metabolism

• thermodynamics?

  study of energy transformations
• first law of thermodynamics?

  total amount of energy in the universe is constant, thus, energy cannot be created nor destroyed -- only transferred and transformed, converting from one form to another
• the suffix '-gonic' means energy
• provide examples of energy transformations in real life?

  • climbing a slide and sliding down: kinetic to potential energy back to kinetic energy
  • sunlight giving plants daily source of free energy for photosynthetic organisms
  • plants transform light to chemical energy -- don't 'produce energy'
  • non-photosynthetic organisms depend on free energy transfer from photosynthetic organisms in form of organic molecules
• relate the first law of thermodynamics to steps in cellular respiration and photosynthesis?

  we can't just create energy, so cellular respiration unleashes the chemical potential energy in consumed food that is stored in its bonds
• system?


  matter under study
• surroundings?

  everything outside system
• closed system?

  isolated from surroundings
• open system?

  energy (and often matter) can be transferred between system and surroundings
• exergonic?

  energy for breaking and forming bonds is RELEASED
• endergonic?

  energy for breaking and forming bonds is ABSORBED
• ATP is in most cases the immediate source of energy that powers cellular work
• oxidation?

  substance loses electrons, is oxidized
• reduction?


  substance gains electrons, is reduced
• the reverse reaction of a redox can happen because reducing and oxidizing agents are pairs
• Given NADH and NAD+ (also applies to FADH2 and FAD+), identify the electron carrier, oxidizing or reducing agent, and determine which molecule has more chemical potential energy?

  NAD+: electron acceptor, oxidizing agent, has less chemical potential energy

  NADH: electron carrier, can donate electrons and reform NAD+, reducing agent, more chemical potential energy

  FADH2: electron acceptor, reducing agent, more chemical potential energy

  FAD+: electron donor, oxidizing agent, has less chemical potential energy
• NADH?

  can donate electrons (becomes oxidized) and reforms NAD+

  • reducing agent
  • electrons in NADH represent stored energy that can make ATP
• NAD+ and NADH redox

  A) oxidizing

  B) reduced

  C) oxidized

  D) reducing

  
• four major stages of cellular respiration?

  1. Glycolysis -- break down glucose into two molecules of pyruvate (doesn’t need oxygen, occurs in cytoplasm)
  2. oxidative decarboxylation -- pyruvate oxidation (requires oxygen, occurs in mitochondria)
  3. krebs/citric acid cycle -- completes breakdown of glucose (requires oxygen, occurs in mitochondria)
  4. ETC and oxidative phosphorylation -- generates ATP (requires oxygen, occurs in mitochondria)
• List different sources of stored energy in the human body and their properties?

  Sources in order:

  1. carbs -- e.g. glycogen, plants storing as starch

  • Glucose is the most usable source of energy -> cells turn to other fuels ONLY if glucose supplies depleted

  1. Lipids (fat)

  • When glucose depleted, this becomes source of energy

  1. Protein -- e.g. muscle tissue

  • Final resort when no energy forms are available -> cell breaks down OWN structures to obtain energy (NOT GOOD)
• goal of cellular respiration?

  convert stored energy to organic fuel to ATP

  • break 6-carbon glucose down and release 6 CO2 molecules
  • move glucose electrons to oxygen and combine with hydrogen ions to form 6 H2O molecules
  • collect energy as ATP
• Describe the functions of the different metabolic enzymes and name their class

  A) redox

  B) phosphorylation

  C) cleavage

  D) decarboxylation

  E) hydration

  F) isomerization

  G) synthesis

  H) oxoreductase

  I) transferase

  J) lyase

  K) lyase

  L) lyase

  M) isomerase

  N) ligase

  
• Glycolysis = ‘splitting of sugar’ from 6C glucose to 3C pyruvate (which has to make its way into the mitochondria), occurring in the cytoplasm of the cell

  • Atoms on the two 3C molecules add up to the 6C molecule that it was split from 
  • only one of two 3C compounds will continue in the latter half of the glycolytic reactions
• which steps are energy investment in glycolysis?

  steps 1 - 5
• which steps are energy payoff in glycolysis?

  steps 6 - 10
• Explain why the first half of glycolysis is called energy investment and the second half energy payoff?

  • Energy investment phase: ATP (energy) converted back to ADP -> oxidized -> energy invested
  • Energy payoff phase: ADP converted to ATP (energy) -> reduced -> energy paid off
• Explain why all the reactions in the energy payoff is doubled?

  This happens twice for each molecule of glucose since glucose is split into two three-carbon molecules, both of which will go through the final steps of the pathway (energy-releasing phase)
• List the numbers of each energy molecule produced and be able to identify the steps in which they were generated or used?

  aerobic respiration glycolysis

  A) 2

  B) 2

  C) 0

  D) 0

  E) cytosol

  
• anaerobic respiration?

  respiration in absence of oxygen

  • glycolysis
  • alcoholic fermentation (yeast)
  • lactic acid fermentation (humans)
• pyruvate continues to the kreb cycle and the ETC to synthesize ATP only in the presence of oxygen
• If no new atp is made during fermentation, then why doesnt metabolic process end at pyruvate when in anaerobic conditions?

  NAD+ converts back to NADH to keep the cycle going
• Describe the process of lactic acid fermentation and alcohol fermentation?

  Lactic acid fermentation -- pyruvate reduced directly with NADH to form lactate as a waste

  1. Lactate dehydrogenase converts pyruvate -> lactic acid
  2. Final product: lactic acid/lactate (3C)
• Explain why burning after lactic acid buildup?

  burning sensation = buildup of acid in the muscles during intense exercise

  • Stops muscle cells from contracting and relaxes (through buildup)
• pyruvate oxidation

  A) 0

  B) 2

  C) 0

  D) 2

  E) matrix

  
• coenzyme A (Coa-sh)?

  large organic molecule, active functional group is thiol
• krebs cycle?

  aka citric acid cycle, tribcarboxylic acid cycle

  • generates more high energy molecules (NADH, FADH2, ATP)
  • produces additional byproducts like CO2
  • for each turn:
  • two carbons exit completely as CO2 (byproduct)
  • 3 NADH and one FADH2 formed
  • 1 ATP made by substrate-level phosphorylation
• FAD?

  flavin adenine dinucleotide (oxidized form)
• kreb cycle count

  A) 2

  B) 6

  C) 2

  D) 4

  E) matrix

  
• glycolysis happens in the?

  cytoplasm
• summary of glycerol phosphate shuttle?

  Electrons from NADH shuttled into mitochondria onto FAD -> FADH2 in matrix

  • Mostly in brain tissue and skeletal muscle tissue