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Bio 225 > Energy & Cellular Metabolism > Flashcards

Energy & Cellular Metabolism Flashcards

1
Q

chemical composition of animals

A

carbon = predominant molecule
organic molecules
-carbon bonds saturated with oxygen or hydrogen
-nitrogen participates in structure and function of molecules

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2
Q

major molecules of animals

A
  • carbohydrates: 1% of body weight: C,H,O
  • lipids: 15% of body weight: C,H,O
  • proteins: 17% of body weight: C,H,O,N
  • nucleic acids: 2% of body weight: C,H,O,N
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3
Q

what makes up the other 55-65% of body mass?

A

water

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4
Q

metabolism

A

sum total of an organism’s biochemical reactions

  • catabolism
  • anabolism
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5
Q

catabolism

A

breakdown of organic molecules into simpler compounds to release the energy stored in chemical bonds
-complex -> simple

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6
Q

anabolism

A

synthesis of organic molecules required for

  • cell structure
  • function and
  • storage of energy
  • simple -> complex
  • building, resynthesizing, making larger and more complex molecules
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7
Q

released energy is utilized to perform cellular work and physiological processes

A
  • biochemical work: anabolic and catabolic reactions
  • transport work: transport of material across plasma membrane or epithelial lining
  • mechanical work: generate force and movement - beating of cilia, contraction of muscles and movement of chromosomes , any movement in the body ex.cell division will consume energy
  • repair and maintenance: renewal of cells
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8
Q

flow of chemical energy

A
  • ADP +Pi + energy from food -> ATP glycolysis and Krebs cycle
  • ATP -> ADP + Pi + energy available for cellular functioning
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9
Q

how do plants store glucose?

A

starch

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10
Q

how do humans store glucose?

A

glycogen

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11
Q

energy hierarchy

A
  • glucose
  • breakdown of glycogen
  • lipids
  • protein resources
  • nucleic acids
  • note: under normal conditions, never going to kill cells to get nucleic acids energy
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12
Q

metabolizing

A
  • when metabolizing these molecules, end up with CO2 and H2O
  • when metabolizing proteins, generate ammonia/nitrogen products
  • ammonia is toxic (nitrogenous waste)
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13
Q

energy requiring cell functions

A
  • force and movement
  • active transport across membranes
  • molecular synthesis
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14
Q

where is energy stored and released?

A

energy is stored in chemical bonds and energy is released when bonds are broken

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15
Q

energy storage molecules

A

stable molecules such as sugars, starch, glycogen, fats and proteins

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16
Q

energy carriers

A 
NADH (reduced form captures energy)
NAD+ (oxidized form releases energy)
FADH2/FAD
-most versatile is ATP
-capture energy for short time
-hydrolyze so that energy can come out
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17
Q

Why is ATP a suitable molecule for this purpose (good energy carrier molecule not storage)?

A
  1. because of its structure
    - covalent bonds provide stability
    - negative charges (oxygen) provide instability: neg charges close -> pull away from each other, easy to fall apart
    - stability/instability of ATP structure makes it an ideal molecule for quick release of energy
    - ATP/ADP + Pi -> recyclable in any physiological scenario
    - bonds break: energy released
    - ATP moves backwards for ATP synthesis
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18
Q

order of preference as fuel

A
  • glucose: 1st choice for substrate
  • glycogen
  • fats-fatty acids and triglycerides: don’t convert to pyruvate
  • proteins: some amino acids convert to pyruvate- gluconeogenic pathway
  • nucleic acids
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19
Q

glycerol

A

glycerol is an alcohol which can convert to pyruvate which can covert to glucose
-gluconeogenic pathway

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20
Q

energy metabolism

A
  • oxidative metabolism: glycolysis and oxidative phosphorylation
  • when proteins are phosphorylated, they are typically activated
  • intermediary metabolism: big web of metabolism - glucose, protein metabolism
  • mix of catabolic and anabolic activity
  • not exclusive of each other
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21
Q

review: energy metabolism

A
  1. glycolysis
  2. krebs cycle
  3. electron transport system
  4. oxidative phosphorylation
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22
Q

glycolysis

A
  • first step in energy metabolism
  • no oxygen needed
  • occurs in cell cytoplasm
  • substrate: 1 glucose
  • end product: 2 ATP + 2 pyruvate
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23
Q

glycolysis: pros and cons

A
  • low energy yield: yields only 2 ATP compared to TCA cycle where 2 pyruvates (of glycolysis) yield total 36 ATP
  • ATP production rate is fast: glycolysis (oxidative metabolism) preferred when immediate energy is needed
  • does not need oxygen: body depends on ATP in early phases of INC demand for energy, oxygen comes towards end of process, even before we INC rate of respiration - glycolysis can of on and help us with 2 ATP
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24
Q

more 02 needed for cellular respiration

A

at times, we reach level of activity where we can’t breathe as hard as we need too -> greater demand for O2 in tissues, rate of respiration does not match demand - low O2 environment -> depend on glycolysis

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25
Q

low oxygen conditions (over-exercise)

A

muscle cells depend on glycolysis

  • lactic acid build up may cause muscle fatigue/pain
  • ultimately lactic acid is converted back to pyruvate in the liver - gluconeogenesis
  • in presence of 02 (aerobic condition), pyruvate moves to the Krebs cycle
  • yeast and bacterial fermentation results in ethanol production
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26
Q

oxidative metabolism is always there, always breathing

-shifts: depending more on glycolysis and less on oxidative respiration when?

A

when rate of respiration does not match cellular demand for 02 -> more pyruvate is building up -> muscles ache the next day -> pyruvate converts to lactic acid -> accumulates in muscle cells -> destruction, slowing of activity -> pain in muscles bc day before cells not getting enough o2 -> muscle cells depend more on glycolysis than Oxidative metabolism -> end product is lactic acid buildup in muscle

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27
Q

Should you exercise the day after a workout when you are sore?

A

yes, the lactic acid in muscle buildup needs to go to liver and convert to pyruvate -> want to get rid of lactic acid from muscle -> more blood flow -> use muscles (similar activity at lower level intensity) -> inc blood flow -> lactic acid gets out of muscle to liver -> converts to pyruvate (gluconeogenesis)

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28
Q

formation of acetyl coA

A

see diagram

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29
Q

Krebs cycle

A
  • occurs in mitochondrial matrix
  • amphibolic pathway: any chunk of processes can occur at any time, accumulation of catabolic and anabolic
  • energy carrier molecules (NADH and FADH2) are produced that pass electrons to the electron transport system are produced
30
Q

do we use glycolysis to meet our physiological needs?

A

yes

31
Q

does pyruvate always enter TCA/Krebs cycle?

A

no, because can convert to lactic acid

32
Q

election transport system/chain (ETS/ETC)

A
  • occurs on inner mitochondrial membrane
  • four protein complexes (1,2,3,4) and two electron carriers (ubiquinone and cytochrome c) make ETS
  • electron are transferred from electron donors to electron acceptors through REDOX REACTIONS (both oxidation and reduction occurring simultaneously)
  • electron transfer is coupled with the transfer of protons (H+ ions) across mitochondrial membrane, creating an electrochemical proton gradient
  • at the “bottom”, oxygen captures the electrons and H+ to form water
  • the gradient drives the synthesis of ATP
33
Q

as electrons move from protein to another, protons are produced

A

-protons accumulate in inter membrane space

34
Q

in the last protein of ETC chain

A
  • protons produced and o2 present in cells (coming from the air we breathe)
  • o2 gets absorbed in blood and goes to tissues
  • o2 enters tissue
  • this o2 is required in last reaction (when o2 and protons interact) -> water and co2 produced
35
Q

chemiosmosis

A

the coupling of the electron transport chain to ATP synthesis

36
Q

ATP Synthase

A
  • the protein complex ATP synthase in the crustal is the only place where H+ diffuses back to the mitochondrial matrix
  • as hydrogen ions flow down their gradient, they cause the cylinder portion and attached rod of ATP synthase to rotate
  • the spinning rod causes a conformational change in the knob region, activating catalytic sites where ADP and inorganic phosphate combine to make ATP
37
Q

ATP Synthase CONT

A
  • facilitate synthesis of ATP
  • provides channel, opening for protons to pass through
  • channels work according to concentration gradient
  • protons move into mitochondrial matrix -> conformational change in intracellular domain (cytosol) -> ATP synthase activation
38
Q

inner membrane of mitochondria

A
  • ETC located

- ATP synthase protein embedded

39
Q

if o2 need not met, depend on glycolysis

A

oxygen at the end of the process is an important regulator of metabolism picture

  • makes us breathe at faster rate
  • more exercise = more water produced
  • metabolic water produced -> cellular water
40
Q

role of enzymes and hormones in metabolism

A

hormones and enzymes regulate metabolism by determining:

  1. when the rate of reaction will change
  2. where it will take place, tissue specific
  3. which substrates are we going to use, how long the switch will take place
    - hormones act at the broader level of regulation (global)
    - hormones regulate enzyme activity
    - enzymes regulate specific biochemical steps in the pathway of energy generation
41
Q

enzyme action

A
  • enzymes are catalysts only: do not initiate rxn or pathway, they simply make the environment more conducive for activity to take place
  • enzymes are substrate specific
  • enzymes lower the activation energy requirement by:
  • > substrate orientation/presentation (bring molecules closer)
  • > weakening the bonds in substrate molecule
  • > providing a conducive micro environment
42
Q

activation energy

A

the Ea needs to metabolize these substrates is higher than the energy that is available in our environment
-once Ea req is lowered then activity takes place

43
Q

glucose- 2 scenarios

A

glucose enters the cell -> plasma membrane

  1. if no excess energy: converts gluco 6 phosphate to glucose
  2. if energy demand is high -> converts to pyruvate
44
Q

hexokinase

A

gets activated and promotes conversion of glucose to glucose 6 phosphate

45
Q

phosphofructokinase

A

moves the reaction forward and no stopping until last reaction

46
Q

pyruvate kinase

A
  • last regulator
  • activity depends on how much pyruvate accumulated
  • too much pyruvate: backwards reaction will slow down
47
Q

3 enzymes play key role in regulating rate of glycolysis and fate of gluco-6-phosphate

A
  • move forward in glycolysis or stored as glycogen in cells

- because of influence of hexokinase bc that molecule cannot leave the cell once it is converted to glucose 6 phosphate

48
Q

glucose 6 phosphate

A

no transporters for this

49
Q

phosphorylation

A

may lead to activation or inactivation of enzymes

-regulated by enzymes

50
Q

glycogen phosphorylation

A

-when phosphorylated, it is activated

glycogen breakdown enhanced and promoted

51
Q

glycogen synthase

A
  • when phosphorylated, it is not active
  • inactive form leads to deactivation
  • inhibits glycogen synthesis
52
Q

glycogen synthase (active)

A

glucose converts to glycogen

53
Q

glycogen phosphorylase (active)

A

glycogen converts to glucose

54
Q

glucagon

A
  • promotes glycogenolysis

- inhibits glycogenesis

55
Q

enzyme location is tissue specific

A

ex. only liver contains glucose 6-phosphatase

56
Q

skeletal muscle ex.

A

trapped in skeletal muscle cells

  • glucose enter cell and hexokinase activated and converts to glucose 6 phosphate
  • only that cell is capable of utilizing its own glucose or glycogen bc no transport for glucose 6 phosphate
  • 2 options: store as glycogen and use later on or if we need energy, glucose 6 phosphate will enter glycolysis -> production of energy
57
Q

liver cells are unique

A

liver cells are the only cells that provide energy to other cells

58
Q

flow of chemical energy

A
  • heat energy 60% leaves

- 40% of energy goes towards synthesis

59
Q

UCP1

A

uncouples oxidative phosphorylation from electron transport chain

  • norepinephrine and thyroid hormones are invoved
  • H+ diffusing into mitochondria through UCP1 are used for fatty acid metabolism leading to thermogenesis
  • uncoupling activity tied together: activity of ETC chain (proton generator), tied to ATP activity synthesis
60
Q

UCP1 provides channel for proton transfer

A
  • protons moving back into mitochondrial matrix
  • less protons moving towards ATP synthesis -> ATP synthesis rate dec-> goes towards fat metabolism -> heat production -> maintains body temp as heat leaves the body
61
Q

if an animal is feeling cold

A

cold is a stressor

  • stress stimulates production of norepinephrine/epi
  • cold temp activates T3/T4 production by acting through TRH/TSH mech
  • epi/norepi and T3/T4 stimulate insertion of protein called UCP1 in inner mitochondrial membrane
62
Q

role of hormones in intermediary metabolism

A

glycogen synthesis and glycogen breakdown

63
Q

Glycogen Synthesis and Breakdown

A
  • actively inhibits glycogen breakdown: glycogenolysis
  • insulin promotes uptake of glucose and glycogenesis (synthesis of glycogen)
  • glucagon and epi: promotes glycogenolysis
64
Q

glucagon and epinephrine

A
  • promotes glycogenolysis
  • inhibits glycogenesis
  • these 2 types of hormones act antagonistically: one promoting glycogen synthesis
  • together promoting glycogen breakdown
65
Q

gluconeogenic pathway

A

pyruvate -> glucose
glucose -> pyruvate
stimulated by hormones like glucagon, cortisol

66
Q

cortisol and GH

A

synergistically promote gluconeogenesis: breakdown of protein to promote energy so that glucose can be spared for utilization in brain -> big picture regulated by hormones

67
Q

reaction regulators determine

A
  1. stimulation/facilitation or inhibiting
  2. rate
  3. termination (by switching substrates)
68
Q

reaction regulators

A
  1. hormones (global picture)
  2. enzymes (specific target points)
  3. reaction substrate (strong reaction regulators)
  4. reaction product (end products react as regulators)
69
Q

substrate/pathway preference during varying energy demands

A

currency: ATP
substrates: creatine phosphate (phosphocreatine), glucose/glycogen/fat/proteins
pathways: creatine phosphate cycle, oxidative pathway, anaerobic pathway

70
Q

which of the following hormones simultaneous stimulate glycogenolysis (breakdown) and inhibit glycogenesis (synthesis) by phosphorylating enzymes in the same cell?

A

glucagon

71
Q

ATP is generated by

A
  1. phosphorylation of ADP in cytosol. Pi comes from creatine phosphate
  2. oxidative phosphorylation (includes glycolysis)
  3. anaerobic respiration -glycolysis. pyruvate converts to lactic acid
72
Q

oxygen debt

A

ATP production to restore homeostatic levels of resources such as creatine phosphate and glycogen

Bio 225 (1 decks)

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