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FINAL Unit 3 Flashcards

1
Q

What is meant by growth and division of individual cells?

A

growth in cells = cell division = binary fission

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2
Q

What is meant by growth and division of a population?

A

growth in population = growth phases

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3
Q

What are 4 things bacteria can do?

A
  • self-replicate
  • store/transmit genetic info
  • harness energy from environment
  • maintain a separation between internal and external environment
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4
Q

How do bacteria grow and divide?

A

through binary fission

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5
Q

What is binary fission?

A

form of asexual reproduction with the result of two identical cells from one bacterial cell

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6
Q

Describe the process of binary fission.

A
  1. circular bacterial DNA molecule is attached by proteins to inner membrane
  2. DNA replication begins at a specific location and proceeds bidirectionally around the circle
  3. newly synthesized DNA molecule is also attached to inner membrane, near the attachment site of the initial molecule
  4. as replication proceeds, cell elongates symmetrically around the midpoint, separating DNA attachment sites
  5. cell division begins with synthesis of new membrane and wall material at midpoint
  6. continued synthesis completes the constriction and separates daughter cells
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7
Q

What is one round of cell division equivalent to?

A

one generation = one doubling of bacterial population

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8
Q

What are the 4 phases of population growth in a batch culture?

A
  • lag —
  • exponential /
  • stationary —
  • death \
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9
Q

Describe the lag phase in population growth.

A
  • individual bacterial cells are growing but not readily dividing
  • cells are making tools needed to thrive in new environment such as expressing protein-coding genes (for structural/integral membrane proteins, macromolecules)
  • length of phase depends on difference in environment conditions (previous conditions –> present conditions)
  • overall population does not display a net increase in growth
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10
Q

Describe the exponential phase in population growth.

A
  • bacteria have fully adapted to their surrounding environment and maximized all benefits the can from nutrient media
  • bacterial are at optimal conditions and want to replicate
  • overall population of cells undergo binary fission at constant rate
  • replication is at its maximum and cell number increases exponentially (2^n)
  • cells are readily dividing and growth of population occurs exponentially
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11
Q

Describe the stationary phase in population growth.

A
  • key nutrients are beginning to deplete, therefore bacteria begin to compete with other cells in order to obtain nutrients
  • metabolic waste products released from bacterial cells begin to build up in environment and is toxic to cells
  • net zero growth rate in overall population, which results from equal amount of individual cells actively dividing as there are cells dying
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12
Q

Describe the death phase in population growth.

A
  • loss of nutrients, build-up of waste products, and lack of optimal conditions results in death of many cells
  • in overall population, more cells are dying than actively dividing, therefore the growth of the overall population dramatically decreases
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13
Q

What is an anabolic reaction?

A

reaction that builds molecules from smaller units and require an input of energy (ATP)

ie. synthesis fo macromolecules

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14
Q

What is a catabolic reaction?

A

reaction that breaks down molecules into smaller units and produces ATP

ie. carbohydrates to sugars, fats to fatty acids and glycerol, proteins to amino acids

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15
Q

Why do cells need nutrients?

A
  • are the building blocks of macromolecules

- used to make ATP

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16
Q

What type of nutrients are required for metabolic function of the cell?

A
  • major bioelements: C, S, N, P, O, H
  • minor bioelements: Fe, Ca, Mg
  • vitamins
  • electrons that are used to carry energy from food to electron transport system to make ATP
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17
Q

How do cells make ATP?

A

capture energy in bonds of food

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18
Q

What is ATP?

A

carries of energy, used for cells to do work

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19
Q

What is Gibbs free energy?

A

amount of energy available to do work

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20
Q

What is an exergonic reaction?

A
  • ΔG
    releases energy and proceeds spontaneously
    catabolic
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21
Q

What is an endergonic reaction?

A

+ ΔG
requires input of energy and is not spontaneous
anabolic

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22
Q

What are reactants in terms of carbon?

A

reduced forms of carbon that are weakly bonded

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23
Q

What are products in terms of carbon?

A

oxidized forms of carbon that are strongly bonded

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24
Q

Describe an anabolic reaction in terms of the Gibbs free energy equation.

A

less disorder (-ΔS) and more chemical energy in bonds (+ΔH)

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25
Q

Describe an catabolic reaction in terms of the Gibbs free energy equation.

A

more disorder (+ΔS) and less chemical energy in bonds (-ΔH)

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26
Q

What is enthalpy?

A

strength of bonds

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27
Q

What is entropy?

A

motional freedom

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28
Q

Describe a system with low stability.

A

enthalpy: weakly bonded
entropy: motionally constrained

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29
Q

Describe a system with high stability.

A

enthalpy: strongly bonded
entropy: motionally free

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30
Q

Explain the role of high energy phosphate bonds.

A
  • accessible chemical energy of ATP is held in bonds connecting phosphate groups
  • at physiological pH, these phosphate groups are negatively charged and have a tendency to repel each other
  • chemical bonds connecting phosphate groups therefore, it contains lots of chemical energy to keep phosphate groups connected
  • this energy is released when new, more stable bonds are formed that contain less chemical energy, and energy can be harnessed to power the work of the cell
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31
Q

Explain the role of high energy phosphate bonds in anabolic polymerization reactions (ie. synthesis of nucleic acid strands).

A

nucleic acid strand polymerization:

  1. 3’ OH of growing strand attacks high energy phosphate bond of incoming nucleotide, providing energy to drive the reaction
  2. two phosphates of incoming ribonucleotides are released as pyrophosphate
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32
Q

How do the chemical properties of ATP make it a good carrier?

A
  • chemical energy in bonds of ATP are used to drive cellular processes
  • ATP serves as a go-between, acting as an intermediary between fuel molecules that store large amount of potential energy in their bonds and activities of the cell that require an input of energy
  • core of ATP is adenosine (adenine base + ribose sugar) and ribose is attached to triphosphate
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33
Q

What is hydrolysis?

A

break down of polymers into subunits, and one product gains H+, one gains OH-

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34
Q

Describe the hydrolysis of ATP.

A

exergonic reaction

ATP + H2O —> ADP + Pi (inorganic phosphate)

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35
Q

Is ATP or ADP more stable?

A

ADP is more stable because there is less chemical energy in bonds

ADP: 2 phosphate groups
ATP: 3 phosphate groups

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36
Q

Where does the release of free energy during ATP hydrolysis come from and what is it used for?

A

breaking weaker bonds (with more chemical energy) in reactants, and forming more stable bonds (with less energy) in products

energy drives chemical reactions/other processes that require energy input

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37
Q

What is energetic coupling?

A

process in which spontaneous reaction drives a non-spontaneous reaction

  • net ΔG must be negative
  • two reactions must occur together
  • in some cases, coupling can be achieved if two reactions share an intermediate
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38
Q

Describe energetic coupling in ATP hydrolysis.

A

hydrolysis of ATP drives the formation of glucose 6-phosphate from glucose

  • phosphate group transferred to glucose is released during hydrolysis
  • ATP hydrolysis provides thermodynamic driving force for non-spontaneous reaction and shared phosphate group couples the two reactions together
  • after hydrolysis, cells need to replenish ATP: synthesis of ATP from ADP and Pi is endergonic, and in some cases exergonic reactions can drive synthesis of ATP by coupling
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39
Q

Describe the favourable energy balance in energetic coupling in ATP hydrolysis.

A
  • high energy phosphate groups from ATP transferred to intermediates, increasing the free energy of the intermediate (lower stability)
  • removal of high energy phosphate groups from activated intermediates in coupled reactions result in decrease in free energy (higher stability)
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40
Q

What is the ATP-ADP system?

A

core of energetic coupling between catabolic and anabolic reactions

  • ADP: energy acceptor
  • ATP: energy donor
  • reactions with ΔG more negative than that of ATP hydrolysis transfer a phosphate group to ADP by energetic coupling
  • reactions with ΔG less negative receive phosphate group from ATP by energetic coupling
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41
Q

What is metabolism?

A

reduced carbon compounds are oxidized to CO2 and difference in potential energy is captured as ATP and used to do cellular work

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42
Q

How do cells capture energy?

A

in a series of redox reactions, and the energy is transformed into high energy intermediates that are useable forms of energy for the cell (ie. ATP, NADH, FADH2)

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43
Q

What is an oxidation reaction?

A
  • loss of electrons by an atom (ie. NAD+ and FAD)
  • usually gains an oxygen atom
  • loses hydrogen
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44
Q

What is a reduction reaction?

A
  • gain of electrons by an atom (ie. NADH, FADH2)
  • usually gains an hydrogen atom
  • loses oxygen
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45
Q

How is high potential energy stored and what is it used for?

A

stored in reduced forms of carbon, used to harness energy that’s released in redox reactions

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46
Q

What happens to reduced carbon?

A

oxidized to CO2 to form products that:

  • are more strongly bonded
  • have less potential energy
  • are more oxidized forms of carbon
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47
Q

Give an example of mechanical work.

A

muscle cells

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48
Q

Give an example of chemical work.

A

coupled reactions

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49
Q

Give an example of electrical work.

A

neurons for transporters

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50
Q

What do phototrophs do?

A

capture energy from sunlight

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51
Q

What do chemotrophs do?

A

derive energy directly from chemical compounds

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52
Q

What do autotrophs do?

A

convert CO2 into glucose, are self-feeders

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53
Q

What do heterotrophs do?

A

obtain carbon from organic molecules synthesized by other organisms, they eat other organisms or molecules synthesized/derived from other organisms

54
Q

What are the 4 steps of cellular respiration?

A

glycolysis
acetyl-CoA biosynthesis
citric acid cycle
oxidative phosphorylation

55
Q

What is glycolysis?

A

glucose is partially broken down to produce pyruvate, and energy is transferred to ATP and reduced electron carriers

56
Q

What is acetyl-CoA biosynthesis?

A

pyruvate is oxidized to acetyl-CoA, producing reduced electron carriers and releasing CO2

57
Q

What is the citric acid cycle?

A

acetyl group completely oxidized to CO2, energy is transferred to ATP and reduced electron carriers (amount of energy is double glycolysis and acetyl-CoA biosynthesis combined)

58
Q

What is oxidative phosphorylation?

A

reduced electron carriers from stages 1-3 of cellular respiration donate electrons to electron transport chain and a large amount of ATP is produced

59
Q

Describe the general concepts of cellular respiration.

A
  1. glucose is oxidized to CO2
  2. electrons are transferred from glucose to electron carriers, which get reduced (NAD+ —> NADH)
  3. at ETC, electron carriers get oxidized from NADH —> NAD+
  4. electrons move along ETC to terminal electron acceptor O2
60
Q

How can you recognize reduced and oxidized molecules?

A

reduced: increase in C-H bonds
oxidized: decrease in C-H bonds

61
Q

Describe the redox reactions in cellular respiration.

A

oxidation:
C6H12O6 —> CO2
- carbon atom is oxidized because oxygen atom is more electronegative than carbon

reduction:
O2 —> H2O
- oxygen atoms is reduced because oxygen atom is more electronegative than hydrogen

62
Q

Where does cellular respiration occur in bacterial cells?

A

glycolysis: cytoplasm
acetyl-CoA biosynthesis: cytoplasm
citric acid cycle: cytoplasm
oxidative phosphorylation: cell membrane

63
Q

Where does cellular respiration occur in eukaryotic cells?

A

glycolysis: cytoplasm
acetyl-CoA biosynthesis: mitochondrial matrix
citric acid cycle: mitochondrial matrix
oxidative phosphorylation: inner mitochondrial membrane

64
Q

What is ATP generated by in cellular respiration?

A

substrate-level phosphorylation and oxidative phosphorylation

65
Q

Describe the process of substrate-level phosphorylation.

A

way of generating ATP when phosphate group is transferred to ADP from enzyme substrate (in this case, an organic molecule) during glycolysis and citric acid cycle

  • organic molecule transfers phosphate group directly to ADP
  • single enzyme carriers out two coupled reactions: hydrolysis of organic molecule to yield a phosphate group and addition of that phosphate group to ADP
  • hydrolysis reaction releases enough free energy to drive synthesis of ATP
66
Q

How much ATP does substrate-level phosphorylation generate?

A

12% of total ATP generated in cellular respiration

remaining 88% is generated by oxidative phosphorylation

67
Q

What is the electron transport chain?

A

transfers electrons along series of membrane-associated proteins to a final electron acceptor and harness energy released to produce ATP

  • electron carriers transport electrons released during catabolism of organic molecules to ETC
  • central to energy economy of most cells
68
Q

What is the endosymbiont theory?

A

mitochondria originated from ancient bacteria engulfed by eukaryotes

69
Q

Describe the characteristics of mitochondria that support theory of endosymbiosis for their origin.

A
  • have cell membrane and outer membrane
  • have their own DNA in circular genome
  • mitochondrial genome is small
  • grow and multiply by binary fission
  • have own ribosomes, synthesizes proteins
70
Q

Describe characteristics of the mitochondria.

A
  • same size and shape as bacteria
  • intermembrane space: between outer and inner membranes
  • matrix: inner chamber
71
Q

Describe the process of glycolysis.

A

begins with molecule of glucose and produces two 3-carbon molecules of pyruvate and net total of two molecules of ATP and two molecules of NADH (electron carrier)

NADH is later used to contribute to synthesis of ATP during oxidative phosphorylation

72
Q

Describe the energy in glycolysis.

A
  • ATP produced directly by substrate-level phosphorylation
  • change in free energy is initially positive because glycolysis is coupled to ATP hydrolysis at first
  • SLP occurs when phosphorylated substrate is even more unstable than ATP
73
Q

What are the high energy intermediates in cellular respiration?

A
  • NADH, FADH2, ATP electrons acceptors are reduced in steps 1-3
  • in step 4, NADH, FADH2 are electron donors
74
Q

What are the inputs and outputs in glycolysis?

A

inputs:

  • glucose (substrate)
  • NAD+ (electron carrier)
  • ADP (electron carrier)

outputs:
- pyruvate (substrate)
- NADH (electron carrier)
- ATP (electron carrier)

75
Q

Describe the process of pyruvate oxidation/acetyl-CoA synthesis.

A
  • pyruvate is transported into mitochondrial matrix where it’s converted to acetyl CoA
  • part of pyruvate molecule is oxidized and splits off to form CO2 (which is the most oxidized, least energetic form of carbon)
  • electrons lost are donated to NAD+ which results in NADH (2 electrons are donated)
  • remaining part of pyruvate molecule (acetyl group COCH3) still contains large amount of potential energy and is transferred to coenzyme A (molecule that carries acetyl group to next set of reactions)
  • forms one molecule of CO2 and one molecule NADH for each pyruvate molecule (two pyruvate from glycolysis, therefore 2 CO2 and 2 NADH is produced from one glucose molecule)
  • one carbon is oxidized as CO2
76
Q

What are the inputs and outputs of pyruvate oxidation/acetyl-CoA synthesis?

A

inputs:
- pyruvate
- coenzyme A
- NAD+

outputs:
- acetyl-CoA
- CO2
- NADH

77
Q

Describe the process of the citric acid cycle.

A
  • acetyl group of acetyl-CoA is completely oxidized to CO2 (6 carbons are oxidized, final breakdown of C-C bonds) and chemical energy is transferred to ATP by substrate-level phosphorylation and to the reduced electron carriers NADH and FADH2
  • NADH and FADH2 donate electrons to ETC, leading to production of much more energy in form of ATP than obtained by glycolysis alone
  • FADH2 is synthesized by FAD picking up two electrons
  • NAD+ electrons are transferred to NADH
  • ATP synthesized by SLP
  • 2 acetyl CoA forms 2 ATP, 6 NADH, 2 FADH2
78
Q

What are the inputs and outputs of the citric acid cycle?

A

inputs:

  • acetyl-CoA
  • ADP
  • NAD+
  • FAD

outputs:

  • coenzyme A
  • CO2
  • ATP
  • NADH
  • FADH2
79
Q

Where does our source of CO2 for breathing come from?

A

release of CO2 during pyruvate oxidation and citric acid cycle

80
Q

How are the big energy drops in citric acid cycle captured?

A
  • NAD+ reduction to NADH
  • reduction of FAD to FADH2
  • ATP synthesis
81
Q

Describe the process of oxidative phosphorylation.

A
  1. electrons are delivered by high energy carriers NADH and FADH2
  2. electrons step down from ETC, protons are pumped into intermembrane space (energy is captured by electrons passed along ETC, energy needed to pump protons)
    - energy from transfer of electrons is released in a series of redox reactions, the energy is used to pump H+ from mitochondria matrix into intermembrane space
  3. ATP synthase uses proton gradient to make ATP
    - movement of electrons through membrane-embedded protein complexes is coupled to pumping of protons from mitochondrial matrix into intermembrane space resulting in an electrochemical gradient
82
Q

What occurs in anaerobic respiration?

A

oxygen accepts electrons at end of ETC (it is a terminal electron acceptor) and is reduced to water: LIVING THINGS NEED OXYGEN

83
Q

What is OxPhos?

A

synthesis of ATP, because oxygen accepts the electrons and ADP is phosphorylated to ATP

84
Q

Why is OxPhos chemiosmotic?

A

H+ is moving through ATP synthase down their concentration gradient

85
Q

Describe the electron transport chain in cellular respiration.

A
  • series of proteins complexes and compounds (4)
  • within each complex, electrons are passed from electron donors to electron acceptors (redox)
  • when oxygen accepts electrons at end of ETC, it’s reduced to form water
86
Q

Describe the proton/electrochemical gradient.

A
  • created by oxidation of NADH and FADH2
  • source of potential energy, if a path is opened through a membrane the resulting movement of protons through membrane is used to do work
  • high concentration in intermembrane space
  • low concentration in mitochondrial matrix
  • tendency for protons to diffuse back to matrix, driven by difference in concentration and charge on two sides of the membrane, but the movement is blocked by membrane
87
Q

What are the inputs and outputs in OxPhos?

A

inputs:

  • ADP
  • O2
  • NADH

outputs:

  • ATP
  • H2O
  • NAD+
88
Q

What are the inputs and outputs in ETC?

A

inputs:

  • NADH
  • FADH2
  • H+

outputs:

  • NAD+
  • FAD
  • H2O
  • ATP
89
Q

Explain the chemiosmotic theory and how ETC drives ATP synthesis using a proton gradient.

A

gradient of protons provides source of energy that is converted into chemical energy stored in ATP

  1. for potential energy of proton gradient to be released, there must be an opening in membrane for protons to flow through: protons in intermembrane space diffuse down their concentration gradient through transmembrane protein channel into mitochondrial matrix
  2. movement of protons through channel must be coupled with synthesis of ATP
    - coupling possible by ATP synthase
90
Q

What are the 2 subunits of ATP synthase?

A

F0: forms channel in inner mitochondrial membrane through which protons flow
F1: catalytic unit that synthesizes ATP

91
Q

How is ATP synthesized by ATP synthase?

A
  • proton flow through F0 makes it possible for enzyme to synthesize ATP
  • flow through F0 causes it to rotate, converting energy of proton gradient into mechanical rotational energy (kinetic energy)
  • rotation of F0 leads to rotation of F1 in mitochondrial matrix
  • rotation of F1 causes conformational changes that allow it to catalyze synthesis of ATP from ADP + Pi
  • mechanical rotational energy converted into chemical energy of ATP
92
Q

Describe how metabolic inhibitors such as dinitrophenol (DNP) can alter the function of ETP.

A
  • DNA inserts into mitochondrial membrane and shuttles protons between intermembrane space and the matrix
  • when DNP is added to mitochondria, inner mitochondrial membrane becomes permeable to protons
  • proton gradient collapses, no ATP synthase activity
  • ETC continues at full capacity: O2 is consumed, heat is generated
93
Q

What is fermentation?

A

process for extracting energy from fuel molecules that does not rely on oxygen or ETC, but instead uses an organic molecule as an electron acceptor

metabolic reaction that converts sugar to acid/gas/alcohol

94
Q

When does pyruvate continue through cellular respiration?

A

in the PRESENCE of oxygen (it has O2 as a TEA”)

95
Q

When is pyruvate broken down by fermentation?

A

in the ABSENCE of oxygen (uses an organic molecule as an electron acceptor instead of O2 TEA)

96
Q

How is fermentation accomplished?

A

through wide variety of metabolic pathways that are important for anaerobic organisms that live without oxygen
- these organisms sometimes use fermentation when oxygen can’t be delivered fast enough to meet the cell’s metabolic needs

97
Q

Where does pyruvate undergo fermentation?

A

cytosol

98
Q

Describe NADH in the absence of oxygen (fermentation) vs. in the presence of oxygen (cellular respiration).

A

fermentation:

  • NADH is oxidized to NAD+ and electrons are donated to substrate in the reaction (when pyruvate is reduced)
  • NAD+ can return to glycolysis to pick up more electrons (phase 2 of glycolysis)

cellular respiration:
- NAD+ is regenerated when NADH donates electrons to ETC

99
Q

What are the two major pathways of fermentation?

A

lactic acid fermentation

ethanol fermentation

100
Q

What is lactic acid fermentation?

A
  • occurs in animals and bacteria

- electrons from NADH transfer to pyruvate to produce lactic acid and NAD+

101
Q

What is ethanol fermentation?

A
  • occurs in plants and fungi
  • pyruvate releases CO2 to form acetaldehyde and electrons from NADH transfer to acetaldehyde to produce ethanol and NAD+
102
Q

How much ATP is formed during fermentation?

Why is it relatively small compared to the amount produced in cellular respiration

A

2 molecules of ATP

  • energetic gain is relatively small compared with yield of cellular respiration because end products (lactic acid and ethanol) are not fully oxidized and still contain large amount of chemical energy in their bonds
  • organisms that produce ATP by fermentation must consume a large quantity of fuel molecules to power the cell
103
Q

Compare the key points of cellular respiration and fermentation.

A

cellular respiration:

  • glucose: carbons are completely oxidized to CO2 because electrons are transferred to O2 or another TEA
  • oxidized carbon atoms are discarded as CO2 waste

fermentation:

  • no next oxidation of carbon
  • electrons are removed from the same carbon atoms and returned to others
104
Q

Contrast ATP synthesis by SLP and OxPhos.

A

SLP:

  • substrate has phosphate
  • enzyme removes phosphate from substrate to phosphorylate ADP
  • ATP is synthesized and substrate loses phosphate

OxPhos:
- membrane-bound enzymes and H+ gradient drives ATP phosphorylation

105
Q

Describe the characteristics of chloroplasts that support the theory of endosymbiosis for their origin.

A

evidence chloroplasts evolved from ancient prokaryote:

  • are surrounded by two lipid bilayers (inner and outer membranes)
  • have their own circular DNA (genomes)
  • grow and multiply by binary fission (independently of eukaryotic cell)
  • have their own ribosomes, synthesize proteins
106
Q

What is the thylakoid membrane?

A

part of chloroplast

  • home of photosystems
  • have chlorophyll
  • capture light energy
107
Q

What is the thylakoid lumen?

A

part of chloroplast

  • where protons accumulate
108
Q

What is the stroma?

A

part of chloroplast

  • equivalent to cyanobacterial cytoplasm
109
Q

What are the two parts that make up the overall process of photosynthesis?

A

light-dependent reactions

light-independent reactions

110
Q

LIGHT DEPENDENT REACTION

Where does it occur?

A

thylakoid membranes of chloroplasts

111
Q

LIGHT DEPENDENT REACTION

What is photophosphorylation?

A

cells use chloroplasts to convert light energy into ATP and NADPH similar to in mitochondria, except the reduced electron carrier is made, not consumed

112
Q

LIGHT DEPENDENT REACTION

Describe the process.

A

oxidation of water to form O2 at photosystem II

  • electrons are supplied by H2O splitting that generates O2
  • light energy is required for PSII to strip electrons from water (H2O splitting)

electrons move along ETC to provide energy to pump protons into lumen

electrochemical gradient is created in thylakoid lumen

more light energy input at PSI energizes the electron to drive the reduction of NADP+

NADPH is synthesized in the stroma and will be used in the Calvin cycle

ATP is synthesized in stroma via chemiosmois and H+ moves through ATP synthase

113
Q

LIGHT DEPENDENT REACTION

Where is chlorophyll?

A

bound to photosystems that form the basis of ETC

114
Q

LIGHT DEPENDENT REACTION

What are photosystems?

A

multiprotein complexes embedded in chloroplast membranes

115
Q

LIGHT DEPENDENT REACTION

Why is PSII referred to as oxygenic phosphorylation?

A

electrons from H2O reduce PSII and release O2

116
Q

LIGHT DEPENDENT REACTION

What is NADPH?

A

nicotinamide adenine dinucleotide phosphate

  • high energy intermediate synthesized in photophosphorylation in stroma and used in Calvin cycle
  • similar to NADH but with extra phosphate group
117
Q

LIGHT DEPENDENT REACTION

What does having both NADPH AND NADH in cells allow?

A

allows cells to differentiate between the 2 electron carriers and their roles

NADH: catabolic reactions
NADPH: anabolic reactions

118
Q

LIGHT DEPENDENT REACTION

Why doesn’t photophosphorylation have TEA?

A

electrons end up on molecule that’s already in chloroplast (ie. NADP+)

NADP+ accepts electrons and becomes NADPH (electron acceptor)

119
Q

LIGHT DEPENDENT REACTION

What is the difference between TEA and electron acceptor?

A

TEA: refers to a molecule taken up by cell from environment (ie. O2 in OxPhos)

electron acceptor: refers to a molecule already present

120
Q

LIGHT INDEPENDENT REACTION

What occurs?

A

Calvin cycle = carbon fixation that takes place in stroma

carbon is fixed: converted from gas state to solid or liquid
carbon is assimilated: converted from inorganic to organic form, involving the reduction of carbon

  • 15 enzyme-catalyzed reactions required
    requires ATP and NADP (strong reducing agent)
121
Q

LIGHT INDEPENDENT REACTION

What is the most important anabolic task of autotrophs?

A

fixing/reducing carbon atoms

122
Q

LIGHT INDEPENDENT REACTION

What uses the Calvin cycle?

A

green plants, algae, cyanobacteria

123
Q

LIGHT INDEPENDENT REACTION

Describe the process.

A
  1. CARBON FIXATION: attachment of CO2 to an organic compound
    - one CO2 reacts with RuBP, producing two 3-carbon molecules
    - enzyme rubsico catalyzes the reaction
  2. REDUCTION: two 3-carbon molecules (aka 3-phosphoglycerate molecules) are phosphorylated by ATP and reduced by NADPH to produce glyceraldehyde 3-phosphate (GAP, a triose phosphate)
  3. REGENERATION: remaining GAP is used in ATP-dependent reactions that generate RuBP

each cycle adds input molecule to substrate that’s regenerated at the end of the cycle

124
Q

LIGHT INDEPENDENT REACTION

What are the inputs and outputs in the Calvin cycle?

A

inputs:
- CO2

outputs:
- GAP: one 3-carbon sugar (triose phosphate) per three CO2

125
Q

LIGHT INDEPENDENT REACTION

What is GAP?

A

glyceraldehyde 3-phosphate

an intermediate in glycolysis that can be made into sugars and fatty acids by feeding into other pathways

126
Q

Describe the fixing, reduction, and assimilation of carbon.

A

before: CO2 O=C=O
- completely oxidized carbon
- only C-O bonds

after: carbohydrates (ie. glucose, protein, polysaccharides, lipids, nucleic acids)
- reduced carbons
- C-H bonds

127
Q

Describe the 3 different mechanisms of ATP synthesis.

A

SLP:

  • light independent synthesis
  • non-chemiosmotic (dependent on phosphorylated high-energy organic molecules

OxPhos:

  • light independent synthesis
  • chemiosmotic (dependent on H+ gradient across membrane)

PhotoPhos:

  • light dependent synthesis
  • chemiosmotic
128
Q

Summary of photosynthesis.

A
  1. light-dependent reactions capture solar energy and power ETC to pump H+ into thylakoid lumen
  2. O2 is produced when H2O splits to feed electrons to ETC
  3. NADPH is produced at the end of ETC
  4. chemiosmosis is used to produce ATP in photophosphorylation
  5. CO2 is fixed by rubisco in Calvin cycle
  6. NADPH and ATP are used in Calvin cycle to produce triose phosphates
  7. triose phosphates are converted into sugars, starch, polysaccharides, metabolites
  8. results in reduced carbon compounds such as glucose for glycolysis
129
Q

LIGHT DEPENDENT REACTION

What are the inputs and outputs?

A

inputs:

  • light
  • ADP+Pi
  • NADP
  • H2O

outputs:

  • O2
  • ATP
  • NADPH
130
Q

What are the inputs and outputs of fermentation?

A

input:

  • glucose
  • ATP

output:

  • lactic acid or ethanol
  • CO2
  • ATP
131
Q

What are the inputs and outputs of photosynthesis?

A

input:

  • H2O
  • CO2
  • energy

output:
- C6H12O
- O2

+ BIOL 112 (30 decks)

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