Unit 3.2 AP Biology

fermentation and cellular respiration

use energy from biological macromolecules to produce ATP; characteristic of all forms of life.

Cellular respiration in eukaryotes

involves a series of coordinated enzyme-catalyzed reactions that capture energy from biological macromolecules.

multiple reactions for...

the controlled release of energy for synthesis of ATP

oxidation

loses electrons, gaining a more positive charge

reduction

gains electrons, gaining a more negative charge

C₆H₁₂O₆ + O₂ --> H₂O + Energy (ATP)

cellular respiration chemical formula

glycolysis, Krebs Cycle, and electron transport

parts of cell respiration

glycolysis

sugar split; biochemical pathway that releases energy in glucose to form ATP from ADP and inorganic phosphate, NADH from NAD+, and pyruvate

glycolysis basic equation

glucose C-C-C-C-C-C + NAD+ ---> pyruvate 2 C-C-C + NADH + ATP

NAD+

electron carrier; accepts e- and H+ to be reduced to NADH

Pyruvate

transported from the cytosol to the mitochondrion, where further oxidation occurs (2 C-C-C)

C-C-C => NAD+ --> NADH, CO₂, acetyl CoA (2C)

pyruvate's path/fate

fermentation

when there is no oxygen, this occurs in the cytoplasmw

aerobic cellular respiration

when there is oxygen, this occurs in the mitochondrial matrix

Krebs Cycle

carbon dioxide is released from organic intermediates, ATP is synthesized from ADP and inorganic phosphate, and electrons are transferred to the coenzymes NADH and FADH₂

how glucose is used in cell respiration

glucose --> 2CO₂ + 4CO₂
6C link Rxn Krebs

acetyl CoA

delivers acetyl group to citric acid cycle (Krebs); goes through the cycle and is oxidized

4 CO₂, 6NADH, 2FADH₂, and 2ATP

two turns of the Krebs Cycle produces

acetyl CoA in Krebs Cycle

oxidized, releasing CO₂, e- and H+ taken in by carriers (NADH and FADH₂

two turns

each glucose molecule powers __________ of the Krebs Cycle

glucose

oxidized to 6 carbon dioxide molecules

(6) oxygen

reduced to 6 water molecules

electron transport chain

Electrons extracted in glycolysis and Krebs cycle reactions are transferred by NADH and FADH2 to this (in the inner mitochondrial membrane); proteins, like a staircase, releasing ATP each "step"

ETC

When electrons are transferred between molecules in a sequence of reactions as they pass through the _____ , an electrochemical gradient of protons (hydrogen ions) across the inner mitochondrial membrane is established.

NADH and FADH₂

oxidized and release e- and H+ (sent to ETC & recycled in glycolysis)

high to low

hydrogen ions move from _________________ concentrations through the ATP synthase, fueled by energy released from ETC to intermembrane space from inner mitochondrial membrane

end of the ETC

2 H+ + 1/2 O₂ --> H₂O

an electrochemical gradient across membranes

The electron transport chain transfers energy from electrons in a series of coupled reactions that establish this

chloroplasts, mitochondria, and prokaryotic plasma membranes.

Electron transport chain reactions occur in these three places

oxygen

In cellular respiration, electrons delivered by NADH and FADH₂ are passed to a series of electron acceptors as they move toward the terminal electron acceptor, _______.

NADP+

In photosynthesis, the terminal electron acceptor is _____ .

oxygen; other molecules

Aerobic prokaryotes use ______ as a terminal electron acceptor, while anaerobic prokaryotes use ______________.

proton gradient

The transfer of electrons is accompanied by the formation of a __________ across the inner mitochondrial membrane or the internal membrane of chloroplasts, with the membrane(s) separating a region of high proton concentration from a region of low proton concentration. In prokaryotes, the passage of electrons is accompanied by the movement of protons across the plasma membrane.

oxidative phosphorylation (CR), and photophosphorylation (PS)

The flow of protons back through membrane-bound ATP synthase by chemiosmosis drives the formation of ATP from ADP and inorganic phosphate.

heat

In cellular respiration, decoupling oxidative phosphorylation from electron transport generates _____. This can be used by endothermic organisms to regulate body temperature.

chemiosmosis

chemical (ion) diffusion

phosphorylate

add a phosphate group (free floating)

overview of cellular respiration

glycolysis: cytosol-- produces ATP via substrate-level phosphorylation
Krebs: mitochondrion -- produces ATP via substrate-level phosphorylation
ETC + oxidative phosphorylation: mitochondrial membrane -- produces ATP via oxidative phosphorylation

substrate-level phosphorylation

phosphate comes from substrate

Fermentation

allows glycolysis to proceed in the absence of oxygen and produces organic molecules, including alcohol and lactic acid, as waste products; purpose is to recycle NADH --> NAD+ so glycolysis occurs

releases

The conversion of ATP to ADP __________ energy, which is used to power many metabolic processes.

overview of glycolysis

produces ATP that is releases; produces pyruvate and O₂ that goes to the Krebs Cycle in the mitochondria

cellular respiration:
require O₂
produce CO₂
produce H₂O
Produce ATP

cellular respiration:
oxidative phosphorylation
Krebs Cycle, link rxn
oxidative phosphorylation
glycolysis, Krebs Cycle, oxidative phosphorylation

reduction reactions

gain of electrons. examples:
2e- + NAD+ H+ --> NADH
2e- + FAD + 2H+ --> FADH₂
2e- + 1/2O₂ + 2H+ --> H₂O

NADH

reduced form of nicotinamide adenine dinucleotide (accepts e-s)

oxidized

glucose is _______ during respiration because it gives e- to NAD+ or FAD

glucose and ATP

reactants of glycolysis

2 pyruvate, 2 ATP, and 2NADH

products of glycolysis

2 ATP

net production of ATP by glycolysis

NAD+

acts electron acceptor in glycolysis

link reaction

takes place in the inner matrix of mitochondria; no ATP used/produced; produces 2 acetyl CoA, 2 CO₂, and 2 NADH molecules

Krebs Cycle

takes place in the mitochondrial matrix; acetyl-CoA introduced from link rxn; one turn produces 1 CO₂, 1 ATP, 3 NADH, and 1 FADH₂ molecules (one glucose molecule doubles aka 2 turns)

the other phases of cell respiration

NADH and FADH₂ for the ETC come from where?

energy released from e- going down ETC

used to move hydrogen ion from areas of low concentration to high concentration through active transport

O₂

final electron acceptor after e- has moved through ETC, producing water. it helps recycle NAD+ and FAD+ through the ETC

water

final product of ETC

back to glycolysis and other rxns

NAD+ and FAD+ go back here after oxidizing (lose e- and H+)

ATP synthase

creates ATP when H+ move from [high] to [low]

production of ATP

from ADP and P, this requires the energy from the flow of H+ through the protein chanell

ADP molecules

are phosphorylated during oxidative phosphorylation

energy

Organisms capture and store _______ for use in biological processes—

photosynthesis

captures energy from the sun and produces sugars; first evolved in prokaryotic organisms.

an oxygenated atmosphere.

Scientific evidence supports the claim that prokaryotic (cyanobacterial) photosynthesis was responsible for the production of this

Prokaryotic photosynthetic pathways

were the foundation of eukaryotic photosynthesis.

Light (ATP) + 6CO₂ + 6H₂O--> C₆H₁₂O₆ + 6H₂O + 6O₂

photosynthesis chemical formula

The light-dependent reactions

of photosynthesis in eukaryotes, they involve a series of coordinated reaction pathways that capture energy present in light to yield ATP and NADPH, which power the production of organic molecules.

chlorophylls

During photosynthesis, ________________ absorb energy from light, boosting electrons to a higher energy level in photosystems I and II.

chlorophyll a

absorbs blue and red light the bestc

chlorophyll b

absorbs blue and green light the best

better

certain colors of light are _______ for certain pigment molecules-- pigments absorb red/blue and reflect green

Photosystems I and II

are embedded in the internal membranes of chloroplasts and are connected by the transfer of higher energy electrons through an electron transport chain (ETC).

Energized electrons

(by light) from PSII go down an ETC. These “lost” are replaced by the hydrolysis of water

hydrolysis of water

water splitting into electrons, hydrogen ions (for ATP Synthase) and oxygen (released)

an electrochemical gradient of protons (hydrogen ions)

When electrons are transferred between molecules in a sequence of reactions as they pass through the ETC, this is established across the internal membrane.

the synthesis of ATP

The formation of the proton gradient is linked to what from ADP and inorganic phosphate via ATP synthase.

NADP+; NADPH

Energized electrons (by light) from PSI go down another ETC and are collected by what? , reducing it to what?.

photosystem II first

pigments take in light energy, and electrons shoot up to higher energy levels

NADPH

NADP+ e- + H+

overview of light reactions

Light E + H₂O split into H+, e-, and O₂ --> PSII --> ETC --> PSI--> ETC--> ATP and NADPH --> Calvin cycle

simplified steps of the light dependent reactions

1. Light hits pigments in PSII, exciting an e- to higher energy plane

2. H₂O splits into O₂ (which leaves), H+ (goes to ATP synthase), and e- (goes to PSII)

3. e- go down an ETC (chemiosmosis, just like in CR)

4. ATP synthase produces ATP

5. e- get to end of ETC at PSI energized by light, go down another ETC

6. e- then taken to NADP+, reducing it to NADPH

7. NADPH + ATP go to Calvin Cycle

basic function of light rxns

capture light energy and store it in ATP + NADPH; split H₂O --> O₂

the Calvin cycle

The energy captured in the light reactions and transferred to ATP and NADPH powers the production of carbohydrates from carbon dioxide here; occurs in the stroma of the chloroplast -- does not directly require light: light independent reaction

rubisco

enzyme that "fixes" (combines) CO₂ with organic molecules in the cycle (intermediates)

reduced in glycolysis

glucose is ...

produced in glycolysis

ATP and pyruvate are ...

reduced in the Krebs Cycle

acetyl CoA is ...

produced in the Krebs Cycle

carbon dioxide, ATP, and NADH are...

reduced in ETC

oxygen is...

produced in ETC

water and ATP are..

reduced in light reactions

water is ...

produced in light reactions

oxygen, ATP, and NADPH are...

reduced in the Calvin Cycle

carbon dioxide is...

produced in the Calvin Cycle

glucose (ADP and NADP+) is...

chlorophyll

contained in the thylakoids; necessary for photosynthesis to absorb light

endergonic

photosynthesis is this kind of reaction because it absorbs (light) energy

the Sun

energy source for photosynthesis

glucose contains 6 carbons

why is it necessary for 6 carbon dioxide molecules to enter the chloroplast

ETC in Calvin Cycle

accepts electrons from transport NADP+ and it goes down the chain. This releases ATP that fuels the hydrogen ions to go across the membrane; then they go through the ATP synthase. All the electrons help turn NADP+ to NADPH and ADP + Pi to ATP

photosystem I

embedded protein complex found in the thylakoid membrane that uses excited electrons to reduced NADP+ into NADPH

photosystem II

the embedded protein complex found in the thylakoid membrane that provides excited electrons to the ETC; source of replacement for electrons released by PSI