Download Document

How Cells Release
Stored Energy
Chapter 7
“Killer” Bees- Aggressive descendents of African
honeybees that were imported to Brazil in the 1950s
– Africanized bee’s muscle cells have
enlarged __________________
ATP Is ____________ Energy Source
•Photosynthesizers get energy from the ___
•Animals get energy second- or third-hand
from ____ or other ____________
•Regardless, the energy is converted to the
chemical bond energy of ____
Making ATP
• All organisms- breakdown of
carbohydrates, fats, and protein
– Plants only - during photosynthesis
Two pathways
Aerobic
Anaerobic
O2 required?
___
___
Process
__________ _________
_________
Location
_________, ____________
__________
Aerobic Respiration
C6H1206 + 6O2
6CO2 + 6H20
________
______
______
______
________
Glucose (C6H12O6)
a simple sugar
2 Pyruvate (three carbons)
6CO2
Aerobic Respiration
2 ADP
2 ____
2 ADP
Glucose 1. ________ 2 Pyruvate
2 NAD+
3. _______
________
6 ADP
2 ______
_______
2 _____
2. _______
8 NAD+
2 FAD+
28 ADP
6 CO2
8 NADH
2 FADH2
_______
Add up total ATP generated : 2+2+6+28=____
Overview of Aerobic Respiration
CYTOPLASM
_________
glucose
energy input to
start reactions
1.GLYCOLYSIS
________
(In cytoplasm)
e- + H
MITOCHONDRION
2 NADH
8 NADH
2 pyruvate
e- + H+
2
CO2
e- + H+
4
2.
____________
KREBS
CO
e- + H
CYCLE
(in mitochondrial
matrix)2
+
2 FADH2
e-
(2 ATP net)
+
2 NADH
___________
ATP
2
ELECTRON
3.
______________
TRANSPORT
PHOSPHORYLATION
(In inner
mitochondrial
H
water
membrane)
32
ATP
ATP
+
e- + oxygen
TYPICAL ENERGY YIELD: 36 ATP
End result:
ATP is generated
1. Glycolysis
Each of _____ steps in glycolysis is catalyzed
by a specific _______.
Divided into two phases:
1. an _____________
phase
• 2 ATP used
2. an _____________
phase.
• 4 ATP + 2 NADH
produced
Net yield in glycolysis
= __ATP + __NADH
The Role of Coenzymes
• ____ and ______ accept electrons and
hydrogen
…then deliver them to the ______
_________ system
2. Krebs cycle
2 ADP
Glucose
2 ATP
________
2 NAD+
2 ADP
2 Pyruvate
2 NADH
2 ATP
______
8 NAD+
2 FAD+
6 CO2
8 NADH
2 FADH2
• If __________ is present, pyruvate enters
the _____________ where enzymes of the
Krebs cycle complete the _________ of the
organic fuel to carbon dioxide.
These are generated by ____________________________
2 ADP
Glucose
2 ATP
2 ADP
2 ATP
2 Pyruvate
What is substrate level phosphorylation?
•An ______ transfers a
phosphate group from an
organic molecule (the
substrate) to ____, forming
____-.
6 CO2
Enzyme
• The Krebs
cycle
consists of
____ steps.
2. Krebs cycle
Named after Hans
Kreb – 1930s
• Each cycle
produces
• one ATP by
_______________
_ ______________
• three _________
• and one _______
Fig. 9.11
• The conversion
of pyruvate and
the Krebs cycle
produces large
quantities of
_____________.
Note the Krebs
cycle is never
depleted of ______:
2 in, 2 out
Fig. 9.12
2 carbon
atoms enter
2 carbon atoms
released as
CO2
3. Electron transport
Coenzymes deliver electrons to electron
transport systems
___________
2 NAD+
Electron
transport
6 ADP
____________
___________ 8 NAD+
2 FAD+
__________
28 ADP
8 NADH
2 FADH2
__________
Add up total ATP generated : 2+2+6+28=_____
Electron transport
glucose
GLYCOLYSIS
pyruvate
KREBS
CYCLE
ELECTRON TRANSPORT
PHOSPHORYLATION
Mitochondria
in-text, p. 116
4 important facts:
• Coenzymes deliver _________ to ET chain
• H+ ions are delivered to ______ compartment
• H+ _________ is created
• ___ is final _____________
ET chain
OUTER COMPARTMENT
NADH
Inner compartment
H20
O2
Making ATP:
__________________ Model
• H+ ions going back to _______
compartment generates _______
ATP
INNER
COMPARTMENT
ADP
+
Pi
Overview of respiration
1 Pyruvate from
cytoplasm enters
inner mitochondrial
compartment.
OUTER COMPARTMENT
NADH
acetyl-CoA
Krebs
Cycle
NADH
NADH
3 NADH and
FADH2 give up
electrons and
H+ to membranebound electron
transport systems.
ATP
2 Krebs cycle and
preparatory steps:
NAD+ and FADH2
accept electrons and
hydrogen stripped
ADP
from the pyruvate.
+ Pi
ATP forms. Carbon
dioxide forms.
INNER COMPARTMENT
4 As electrons
move through the
transport system,
H+ is pumped to
outer compartment.
ATP
ATP
ATP
5 Oxygen
accepts
electrons,
joins with H+
to form water.
6 Following its gradients, H+ flows back
into inner compartment, through ATP
synthases. The flow drives ATP formation.
free oxygen
Fig. 7.5b, p. 114
• How efficient is respiration in generating
ATP?
– Complete oxidation of glucose = ____
kcal/mole.
– Formation of each ATP requires = _____
kcal/mole.
– Efficiency of respiration is
– __ kcal/mole x -_ ATP/glucose
686 kcal/mole glucose
= __%.
• The other approximately 60% is lost as ______.
• Cellular respiration is remarkably ________
in energy conversion.
____________ enables some cells to produce ATP
without the use of _________
• Glycolysis generates
______ whether oxygen
is present (aerobic) or
not (anaerobic).
Problem- Fermentation
(anaerobic catabolism) still
requires NAD+ to accept
electrons.
Fig. 9.17a
Ethanol
Solution-In __________________, NAD+ comes from the
conversion of pyruvate to ______________
• A second solution to the NAD+ problem:
– ___________________________
• ( pyruvate is reduced directly by NADH to form
___________)
– Muscle cells switch from ______ respiration
to lactic acid f____________ to generate
ATP when -____ is scarce.
• The waste product,
lactate causes
muscle fatigue but
ultimately it is
converted back to
pyruvate in the liver.
Lactate
A third solution to the NAD+ problem
• Certain anaerobic bacteria solve NAD+
problem by using compounds from
environment (such as nitrate), NOT
oxygen
• ATP yield is low
Compare respiration and fermentation
Similarities
•Both use glycolysis to generate __________
•Both use NAD+ as an _________________.
Type
NAD+
regeneration
Energy
yield
Respiration
Fermentation
Aerobic
Anaerobic
___
Organic molecules
___ATP
___ ATP
• At a cellular level, human ______ cells can
behave as facultative anaerobes, but
__________ cells cannot.
•For facultative
________________,
pyruvate is a fork in the
metabolic road that
leads to two alternative
Ethanol or
routes.
lactate
Fig. 9.18
7. How do other ________________ fit into
glycolysis and the Kreb cycle??
Answer_________,___________
___________________
can all enter the pathway.
•_____ are degraded to
amino acids, then
deaminated (nitrogen
secreted as urea, ammonia)
•________ are broken
down to glucose.
•______ must be digested to
glycerol and fatty acids.
If glucose is the key to ATP production,
then how do we store glucose??
Animals
Answer- ___________ (in animals)
_______ and _______ (in plants)
• Glucose absorbed by blood
• Pancreas releases insulin
• Insulin stimulates glucose uptake by cells
• Cells convert glucose to __________________
• This traps glucose in cytoplasm where it can be
used for glycolysis
• If ATP _____, glucose stored as _________ in
muscle and liver
Using Glycogen
• When blood glucose low, pancreas
releases _____________
• Glucagon stimulates liver cells to convert
glycogen back to glucose and to release it
to the blood
• (Muscle cells do not _____________ their
stored glycogen)
Energy Reserves
• Glycogen- ___%
• Proteins- ___ %
• Fat – ____%
Linking photosynthesis and respiration
sunlight energy
PHOTOSYNTHESIS
water
+
carbon
dioxide
sugar
molecules
oxygen
AEROBIC
RESPIRATION
in-text, p. 122