OSU MB 302 Final Exam Fall 2018

What are the 3 Glycolytic Pathways

1. Embden-Meyerhof pathway

2. Entner-Doudoroff pathway

3. Pentose Phosphate pathway

Embden-Meyerhof pathway is _____.

Amphibolic (involves both catabolism and anabolism)

Entner-Doudoroff pathway is not in ____

Not in eukaryotes

Pentose Phosphate pathway is in _____ and simultaneous with ____ and ____.

-Is in all organisms

-Is simultaneous with Embden-Meyerhof and Entner-Doudoroff pathways

How many phases are in the Embden-Meyerhoff pathway? What are they and what do they require?

2 Phases:

1. 6C Phase (pay in) requiring 2 ATP where an isomerization occurs between G6P and F6P.

2. 3C Phase (payoff)

Where does the isomerization occur in the Embden-Meyerhoff pathway occur?

What is the route of the Embden-Meyerhoff pathway? Explain the 6C phase and the 3C phase

1. Glucose to G6P via ATP

2. G6P to F6P via isomerization

3. F6P to F-1,6-DP via ATP

4. F-1,6-DP split into 2-3 carbon molecules DHAP and GAP

4. DHAP isomerizes into a GAP, resulting in two GAP's

After 6C phase in Embden-Meyerhoff, how many GAP will there be to carry on 3C phase?

2 GAP after DHAP isomerizes

Payoff Phase?

3C Phase with 2 DHAP

GAP is oxidized to ______ which is an _______ molecule.

What else is produced in this process?

GAP is oxidized to 1,3-BPG which is an unstable molecule. NADH is also produced in this process. NADH goes to ETC to make ATP.

This unstable 13-BPG has an extra phosphate, which did not cost much energy to place there.

How many ATP are produced from substrate level phosphorylation of 1,3-BPG?

2 ATP from 2 ADP due to high energy in phosphate.

Produced from substrate level phosphorylation from phosphate.

During the 3C phase of EM pathway, the two phosphates are repulsive on 1,3 BPG which allows ______ to be phosphorylated to _______ when 1,3 BPG is converted to 3-PG.

This allows ADP to be phosphorylated to ATP, when 1,3-BPG is converted to 3-PG.

PEP donates phosphate to make 2 ATP from ADP to make ______.

Pyruvic acid.

What is all involved in the Embden-Meyerhoff pathway and what is the net yield?

Summary:

-1 glucose used

-2 ATP used

-4 ATP formed

-2 NADH formed

-2 pyruvate formed

Net Yield:

-2 ATP

-2 NADH

2 pyruvate

How are all ATP made in EM pathway?

Substrate level phsophorylation

The NADH that is formed in Glycolysis (EMP) will carry electrons to the_________.

NADH will carry electrons to the ETC and a terminal electron acceptor.

Exogenous electron acceptor (RESPIRATION)

Electron acceptor obtained from environment (O2, nitrate, sulfate, Fe, etc).

If no ETC, ______ will occur.

Fermentation will occur-- transfers NADH via an endogenous electron acceptor

Endogenous Electron Acceptor

Obtained from inside own cell (internal electron acceptor from cell's own metabolism).

Entner-Dourdoroff pathway can be an alternative or in addition to ___________ pathway.

Embden-Meyerhoff pathway

Entner-Doudoroff pathway produces....

Produces NADPH and ATP.

Does not involve glycolysis

Pseudomonas, Rhizobium, Agrobacterium

What all is involved in the Entner-Doudoroff pathway?

1. Glucose to G6P via ATP to ADP.

2. G6P oxidized to 6PG-Lactone forming NADPH from NADH.

3. 6PG-lactone to 6PG

4. 6PG to KDPG

5. KDPG to Pyruvate and GAP.

-GAP then breaks down like EM pathway.

6C Phase of Entner-Dourdoroff pathway

6C phase

-Consumes 1 ATP

-Yields 1 NADPH

-Key intermediate is KDPG

-Yields GAP and Pyruvate

Can use 2nd phase of EM pathway

-Yielding 1 NADH, 2 ATP

Key intermediate in Entner-Dourdoroff pathway which is broken into_____.

KDPG, a 6C, which is broken into pyruvate and GAP.

GAP is then broken into pyruvate.

Net yield of Entner-Doudoroff

Net Yield:

-1 NADPH

-1 NADH

-1 ATP

-2 Pyruvic acid

Entner Doudoroff pathway vs Embden Meyerhof pathway yields

EM Pathway:

-2 ATP

-2 NADH

2 pyruvate

ED Pathway:

-1 NADPH

-1 NADH

-1 ATP

-2 Pyruvic acid

ATP is formed in what process by the EM and ED pathways?

Substrate level phosphorylation

In the EM pathway, the 6C compound is split into _________, whereas in the ED pathway it is split into ______.

EM: DHAP and GAP

ED: GAP and pyruvate

NADPH is formed in which pathway?

Entner-Dourdoroff pathway.

The formation of NADH in EM and ED pathways is a result of _________ of _________ and _________ of __________.

The formation of NADH in EM and ED pathways is a result of oxidation of G3P and reduction of NADH.

Pentose Phosphate Pathway (PPP)

-Used by all organisms

-Provides REDUCING POWER for biosynthesis

-Provides important biosynthetic precursor metabolites

Branches of PPP:

Oxidative Branch: Reducing Power

Reductive Pathway: Everything else.

Pentose Phosphate Pathway

A metabolic process that produces NADPH and ribose 5-phosphate for nucleotide synthesis.

PPP oxidative phase

1. Glucose to G6P via ATP to ADP

2. 2 Oxidations:

-G6P to 6PG via NADP to NADPH (EM pathway)

-6PG to Ribulose-5P via NADP to NADPH

Autotrophs need

Ribulose-5-Phosphate for CO2:

NAD(P)H (reducing power) as well as ATP to reduce CO2 and other molecules.

PPP: Ribose-5-Phosphate Intermediate

Intermediate for nucleic acid biosynthesis (when cells are growing quickly)

PPP: Fructose-6-P Intermediate

Used to cycle back to oxidative branch to make more NADPH for biosynthesis and to make more Ribose-5-P

PPP: Xyulose Intermediate

Cell envelope

PPP: G3P (GAP)

EM pathway or ED pathway for ATP, NAD, NADH

EM, ED, and PPP comparative summaries

SEE IMAGE

Aerobic Respiration Flow

Glycolysis makes pyruvate, utilized in TCA/CAC/Krebs Cycle, which creates NADH or FADH that are reduced to electron carriers and moved to ETC. Electrons to O2 making water.

To get pyruvate into TAC from glycolysis---

Oxidate pyruvate to form NADH and decarboxylation yields CO2--> 3C to 2C.

Acetyl group which is transferred to Coenzyme A that provides energy.

CoA

Provides energy!

When linked to acetate, has high energy sulfur bond that provides energy for next reaction.

Pyruvate Oxidation:

Reduce NAD to make NADH, going from 3C to 2C due to decarboxylation.

2C is acetyl group called acetyl CoA.

Acetyl CoA has how many carbons?

2 carbon from pyruvate--has high energy bond.

Acetyl CoA is merged with ____ in the CAC to make a 6 carbon compound.

Oxaloaccetate, a 4carbon molecule, and makes a 6 carbon molecule.

TCA Cycle: For each pyruvate, what is formed?

-1 CO2 formed

-1 NADH formed to go to fermentation or respiration

TCA Cycle: For each turn of the cycle:

-2 CO2 formed

-1 GTP formed (make ATP or used directly)

-3 NADH formed

-1 FADH2 formed

Electron carriers feed the ______

ETC

TCA Intermediates to know:

-Alpha-ketoglutarate

-Succincyl CoA

-Oxaloaccetate

TCA: Alpha-ketoglutarate and Oxaloaccetate

Important for amino acid biosynthesis

TCA: Succinyl CoA

Important for heme biosynthesis

TCA: Anapleurotic Reaction

Anapleurotic reactions: To replenish the cycle with more OAA to continue cycle.

Pyruvate is carboxylized to form oxaloacetate and replenish the cycle, catalyzed by pyruvate carboxylase.

Requires ATP! Carbon fixation.

1. For aerobic and anaerobic respiration, the terminal electron acceptor is derived from...

2. For fermentation, the terminal electron acceptor is derived from....

1. Somewhere in environment (exogenous EA)

2. Fermentation: From somewhere in cell that they make (endogenous EA).

-No ETC

Fermentation (anaerobic respiration)

-Starts with glycolysis

-Lack or repress ETC making anaerobic respiration impossible

-Partial oxidation of substrate

---Final electron acceptor: organic molecule

---Endogenous electron acceptor

---2 Net ATP/glucose

Final electron acceptor for fermentation

Organic molecule

Net yield of ATP for fermentation

2 net ATP from 1 glucose by substrate level phosphorylation

Fermentation uses ______ as its terminal electron acceptor.

Where does NADH come from?

pyruvate--places electron from NADH on to pyruvate.

NADH comes from glycolysis.

Lactate fermentation

-NADH from glycolysis

-Reduce pyruvate, oxidize NADH

-Yield lactate and NAD+

Alcohol fermentation

-NADH from glycolysis

-Pyruvate decarboxylated to acetaldehyde and reduce, oxidize NADH

-Yield NAD+ and ethanol

Pyruvate oxidation

-Pyruvate reduced and NAD oxidized to add CoA, yielding Acetyl CoA, CO2, and NADH.

PMF uses

ATP synthase, transport, motility, etc.

What do cells do if they do not have an ETC but need a PMF? aka...fermentative cells

Reverse ATP synthase called ATPase.

ATPase: ATP hydrolysis--use ATP, breaks phosphate, and moves protons to periplasmic space.

ATP--> ADP and Pi

Phototrophy and photosynthesis

Phototrophy refers to the use of light energy to fuel a variety of cellular activities.

Photosynthesis

-Capturing & converting light energy into chemical energy.

-"Light reactions": use of light energy to generate ATP and NADPH

--Phototrophy

Photoautotrophy (specific form of phototrophy)

-Photoautotrophy: Reduction & incorporation of CO2

-Carbon fixation via Calvin-Benson cycle: ATP and NADPH used to fix CO2

---all single cell plants and bacteria

Five groups of phototrophic bacteria and archaea

Oxygenic and ETC:

1. Cyanobacteria

Anoxygenic and ETC:

2. Purple sulfur and purple nonsulfur bacteria

3. Green sulfur and green nonsulfur bacteria

4. Heliobacteria

Rhodopsin-Based:

5. Halobacteria (archaea) and protobacteria

Oxygenic vs Anoxygenic

Oxygen: H2O electron donor

Anoxygenic: Other electron donors from environment

Banded iron formations (magnetite)

Cyanobacteria producing oxygen oxidizing reduced iron.

Rhodopsin-Based

Only make ATP with no possibility to make reduced electron carriers.

Oxygenic Photosynthesis

SEE IMAGE

Anoxygenic Photosynthesis

SEE IMAGE

Rhodopsin-Based Image summary

SEE IMAGE

Cyanobacteria

Most abundant photosynthetic, oxygen-producing bacteria (formerly known as blue-green algae).

Caused oxygenation of planet.

Oldest known fossils (3.5ba)

Cyanobacteria can also fix...

Nitrogen and N2 into NH4

Photosynthetic membranes

Layered and stacked; convert energy in sunlight to chemical energy, develop from folds of the plasma membrane; have ETC on membranes.

Prochlorococcus marinus (cyanobacteria)

Most abundant photosynthetic organism on earth.

Chlorophyll a and b

Chlorophyll a and b: absorb in blue (430) and red (665); reflect green and so look green

Chlorophyl have ____ tail.

Long hydrophobic tail aids in attachment to the internal membranes (site of photosynthesis)

Accessory pigments: Carotenoids and Phycobilins

Accessory pigments absorb light in the range not absorbed by chlorophylls. The energy absorbed by accessory pigments is transferred to chlorophyll, thus accessory pigments make photosynthesis more efficient over a broader range of wavelengths.

Capture broader wavelengths.

Pigment Purposes

Energy from light is funneled from pigments to reaction center (water splitting)

Oxygenic Photosynthesis Overview

Z-Scheme!

1. Energy from sunlight excites electrons

Uses light absorbing compound (chlorophyll)

Water is the electron donor

2. Electrons are eventuallytransferred to NADP+ via anelectron transport chainforming NADPH

3. Photophosphorylation

Extracting electrons from water when water is a bad electron donor?

The electrons are moving from a redox potential of about +0.82 volt in water to −0.32 volt in NADPH. Thus enough energy must be available to move them against a total potential of 1.14 volts. The energy to drive that reaction comes from LIGHT

Oxygenic Photosynthesis: NADPH is generated for?

Reducing power!

Photophosphorylation....

The process of generating ATP from ADP and phosphate by means of a proton-motive force generated by the thylakoid membrane of the chloroplast during the light reactions of photosynthesis.

Phototrophy Overview: Linear photosynthetic electron transport and cyclic photsynthetic electron transport

SEE IMAGE

Oxygenic Photosynthesis: Z-Scheme of photochemistry

'Z-scheme' of photochemistry

--2 membrane bound photosystems (PSII and PSI)

--ATP, NADPH are formed in membrane bound ETC

--Electron donor: H2O - Electron acceptor NADP+

Oxygenic Photosynthesis: Part I (PS II)

1. Light reaches PSII reaction center (P680)

--Electrons from Chl are excited to a high energy state

2. Water hydrolyzed 2H2O O2 + 4H+ + 4e-

...thus, replacing chlorophyll electrons

3. Electrons (from step 1) are passed through an ETC

--Proton motive force is generated (protons from water, movement of protons by Q-cycle, and NADPH production (in part II))

--ATP produced by ATP synthase

Oxygenic Photosynthesis: Part 2 (PS I)

Quantum of light hits PSI reaction center

--raised to an excited state

--travels through ETC

--final acceptor is NADP+

Which has more negative electronegativity? PS I OR PS II

PS 1 (slightly)

PMF generated through..

Proton motive force generated through water splitting, Q-cycle and NADPH production large delta pH and potential energy.

Ox. Photo: Electrons move through...

Water is split and moving electrons through.

How many ATP is required per N2 fixed into 2HN3

16 ATP

Linear PET

Linear photosynthetic electron transport:

-Using 8 quanta of light and 4 electrons from water used

-Forms 2 NADPH

-Forms 2 ATP

Cyclic PET

Cyclic photosynthetic electron transport:

-Using 2-4 quanta of light

-1 ATP is generated

-No oxygen formed

-Only PS I used

-No reducing power generated-- NADPH NOT formed

PSI is utilized in only...

Cyclic PET.

Carbon fixation requires...

-2 NADPH

-3 ATP

Anoxygenic Photosynthesis

1. Only 1 PS used (cyclic)

2. H2O IS NOT the electron source

3. No O2 formed

4. Uses bacteriochlorophylls

5. Different mechanisms for generating NADPH

Bacteriochlorophyll: what bacteria and absorbed wavelengths than Chl

Green bacteria, purple bacteria: bacteriochlorophyll

absorbs light of shorter and longer wavelengths than Chl a

Anoxygenic Photosynthesis: Photosynthetic Purple Bacteria

-Photosystem similar to PSII: cyclic physophorylation

---Generates PMF

-As photoheterotroph:

---Use organic source of carbon

---PS used for ATP only

-As photoautotroph need reducing power

---Use reverse electron flow AND external electron donor

---H2S or succinate as external electron donor

---Electrons are drawn off the ETC and pushed UPHILL to NAD(P)+ using PMF.