BIOL 1201 Chapter : Biol 1201 Outline9

11 views10 pages
15 Mar 2019
School
Course
Professor
1
`Chapter 9
CELLULAR RESPIRATION: HARVESTING ENERGY
Energy flows through ecosystems while the chemicals within an ecosystem are recycled
Energy flow: Light => organic molecules => ATP + heat
Respiration: An Overview
>>>>>Cellular respiration and fermentation are catabolic pathways
---Fermentation
-is the pathway in which both electron donors and acceptors are organic
compounds.
-no ATP production
-organic electron donors and acceptors
---Cellular respiration
-is an ATP-producing pathway in which the ultimate electron acceptor is an
inorganic molecule, usually oxygen.
-catabolism of organic molecules
-ATP production
-inorganic electron acceptor
C6H12O6 + 6 O2 => 6 CO2 + 6 H2O + Energy (ATP + heat)
How much energy??
ΔG= -686 kcal/mol of sugar.
>>>>>The ATP generated is used for work and then regenerated
Redox reactions
>>>>>Redox reactions release energy when electrons move closer to electronegative
atoms.
---Redox reactions (a.k.a. Oxidation-reduction reactions)
-are chemical reactions which involve a partial or complete transfer of electrons
from one reactant to another.
---Oxidation
---Reduction
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 10 pages and 3 million more documents.

Already have an account? Log in
2
Generalized redox reaction
Xe- + Y => X + Ye-
Xe- is oxidized to X and Y is reduced to Ye-
X is the reducing agent, and Y is the oxidizing agent
The transfer of electrons doesn’t have to be a complete transfer (shown above) it may
only be a partial transfer (e.g., combustion of methane)
>Cellular respiration as a redox reaction
C6H12O6 + 6 O2 => 6 CO2 + 6 H2O
Carbon and hydrogen of C6H12O6 is oxidized to 6 CO2 and 6 H2O, oxygen of 6 O2 is
reduced to 6 H2O
The valence electrons of carbon and hydrogen lose potential energy as they shift
toward the more electronegative oxygen atoms; the released energy is used to make
ATP
Cellular fuels (e.g., carbohydrates and fats) are rich in C-H bonds
Coenzymes: The Role of NAD+
>>>>>The redox “fall” of electrons in cellular respiration is stepwise and uses (NAD+)
Nicotinamide adenine dinucleotide
Electrons removed from glucose during cellular respiration are not transferred directly to
oxygen, but are first passed to a special electron receptor NAD+
---NAD+
---coenzyme
R R
| dehydrogenase |
H-C-OH + NAD+ =======> C=O + NADH + H+
| |
R’ R’
NAD+ is reduced to NADH, and CHRR’OH is oxidized to CRR’O
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 10 pages and 3 million more documents.

Already have an account? Log in
3
NAD+ has only slightly greater affinity for electrons than other organic molecules.
>>>>>Cellular respiration is a cumulative function of glycolysis, the Krebs cycle, and
electron transport.
Three metabolic stages of cellular respiration
1. Glycolysis
2. Krebs cycle-takes place in mitochondria
3. Electron transport chain and oxidative phosphorylation
>>>>>Glycolysis harvests chemical energy by oxidizing glucose to pyruvate
---Glycolysis
-A multi-step pathway that takes place in the cytoplasm.
-Partially oxidizes glucose (C6) in two pyruvate (C3) molecules.
-Occurs with or without O2
The reactions of glycolysis occur in two phases
Glycolysis: The Initial Steps: Energy Input
1. Energy-investment phase
-uses cellular ATP to phosphorylate glycolysis intermediates
-costs two ATP molecules per glucose
Glycolysis: The Energy Payoff
2. Energy-yielding phase
-produces ATP by substrate-level phosphorylation
-yields 4 ATP molecules per glucose
-reduces 2 molecules of NAD+ to NADH per glucose
---substrate-level phosphorylation+9
-Substrate-level phosphorylation is ATP production by direct enzymatic transfer
of phosphate from an intermediate substrate in catabolism of ATP.
The summary equation for glycolysis
C6H12O6 + 2 NAD+ + 2 ADP + 2 Pi =>
2 C3H4O3 + 2 NADH + 2 H+ + 2 ATP + 2 H2O
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 10 pages and 3 million more documents.

Already have an account? Log in

Document Summary

Is the pathway in which both electron donors and acceptors are organic. Is an atp-producing pathway in which the ultimate electron acceptor is an. Energy flows through ecosystems while the chemicals within an ecosystem are recycled. Energy flow: light => organic molecules => atp + heat. C6h12o6 + 6 o2 => 6 co2 + 6 h2o + energy (atp + heat) >>>>>the atp generated is used for work and then regenerated. >>>>>redox reactions release energy when electrons move closer to electronegative atoms. Are chemical reactions which involve a partial or complete transfer of electrons. Xe- is oxidized to x and y is reduced to ye- The transfer of electrons doesn"t have to be a complete transfer (shown above) it may only be a partial transfer (e. g. , combustion of methane) X is the reducing agent, and y is the oxidizing agent.

Get access

Grade+20% off
$8 USD/m$10 USD/m
Billed $96 USD annually
Grade+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
40 Verified Answers
Class+
$8 USD/m
Billed $96 USD annually
Class+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
30 Verified Answers

Related Documents

Related Questions