LESSON 3b: Cellular Respiration Flashcards
- Step-by-step breakdown
of high-energy glucose
molecules to release
energy - Takes place day and
night in all living cells - Occurs in stages,
controlled by enzymes
Cellular Respiration
An ATP molecule contains potential energy, much like a
compressed spring. When a ________________________________
during a chemical reaction, energy is released
phosphate group is pulled away
This cycle is the fundamental
mode of energy exchange in
biological systems.
ATP-ADP Cycle
ATP—> ADP
-Motion
-Active Transport
-Biosynthesis
-Signal Amplification
ATP is constantly
__________ in your cells
recycled
ADP—> ATP
Oxidation of fuel molecules or Photosynthesis
A ____________
recycles all of its ATP
molecules about once
each minute
working muscle cell
How many ATP molecules is spent and regenerated per second?
10 million
Types of Respiration
-Aerobic Respiration
-Anaerobic Respiration
– Occurs in the presence of
oxygen
– When chemically breaking
down glucose completely,
this process releases large
amounts energy
- Releasing carbon dioxide and
water as waste products
Aerobic respiration
-Occurs if there is a lack of
oxygen available for aerobic
respiration
-Only Glycolysis occurs
-Glucose is incompletely
broken down
-In this type of respiration a
lot less energy is -produced
and most of it is lost as heat.
Anaerobic respiration
Breakdown of
Cellular Respiration
- Glycolysis (splitting of sugar)
- Grooming Phase
- Krebs Cycle (Citric Acid Cycle)
- Electron Transport Chain (ETC)
and Oxidative Phosphorylation
cytosol, just outside of
mitochondria.
Glycolysis (splitting of sugar)
migration
from cytosol to matrix
Grooming Phase
done in mitochondrial matrix
Krebs Cycle (Citric Acid Cycle)
a. Also called Chemiosmosis
b. inner mitochondrial
membrane
Electron Transport Chain (ETC)
and Oxidative Phosphorylation
Electron Transport Chain (ETC)
and Oxidative Phosphorylation is also called?
Chemiosmosis
4 metabolic stages
– Anaerobic respiration
1. Glycolysis
– Aerobic respiration
2. Pyruvate oxidation
3. Krebs cycle
4. Electron transport chain
– respiration without O2
– in cytosol
Glycolysis
– respiration using O2
– in mitochondria
Aerobic respiration
- Breaking down glucose
– “glyco – lysis” (splitting sugar)
– ancient pathway which harvests energy - where energy transfer first evolved
- transfer energy from organic molecules to ATP
- still is starting point for all cellular respiration
– but it’s inefficient - generate only 2 ATP for every 1 glucose
– occurs in cytosol
Glycolysis
Glycolysis: Glucose (6C)——–>__________
2 Pyruvate (3C)
Glycolysis: How many ATP is produced for every 1 glucose?
2 ATP
first cells had no organelles
Prokaryotes
– life on Earth first evolved without free oxygen (O2) in
atmosphere
– energy had to be captured from organic molecules in
absence of O2
Anaerobic atmosphere
Prokaryotes that evolved _________ are ancestors of all modern life.
glycolysis
How many reactions does glycolysis have?
10 reactions
In the last steps of glycolysis, where did the P
come from to make ATP?
P is transferred
from PEP to ADP
How is ATP formed?
ATP is formed when an enzyme transfers a
phosphate group from a substrate to ADP
Glycolysis: Net Gain?
2 ATP
only harvest ____ of energy stored in glucose
3.5%
no O2= ______________
slow growth, slow reproduction
______________ = more energy to harvest
more carbons to strip off
Glycolysis Splits a glucose
molecule into 2 - 3 Carbon
molecules called _________
Pyruvate
Product of Glycolysis
2 ATP, NADH and pyruvate
General formula of Glycolysis
glucose + 2ADP + 2Pi + 2 NAD+ —-> 2 pyruvate + 2ATP + 2NADH
without regenerating _____
energy production would stop
NAD+
How is NADH recycled to NAD+?
Another molecule
must accept H from
NADH
Fermentation (anaerobic): Bacteria, yeast
pyruvate (3C) —-> ethanol (2C) + CO2 (1C)
Fermentation (anaerobic): Animals, some fungi
pyruvate (3C) —> lactic acid (3C)
Example of recycling NADH to form NAD+
Fermentation (Anaerobic Reaction)
Alcohol Fermentation
Dead end process
Lactic Acid Fermentation
Reversible Process
Why is alcohol fermentation a dead end process
-at ~12% ethanol,
kills yeast
-can’t reverse the
reaction
Why lactic acid fermentation a reversible process?
once O2 is available,
lactate is converted
back to pyruvate by
the liver
Pyruvate is a ___________
branching point
3 fates of pyruvate produced by glycolysis
-Anaerobic (Lactic Acid fermentation)
-Aerobic Oxidation
-Anaerobic (Alcoholic fermentation)
Process of ATP Synthase
– set up a H+ gradient
– allow H+ to flow
through ATP synthase
– powers bonding
of Pi to ADP
ADP + Pi–>_____
ATP
Oxidation of Pyruvate happens where?
mitochondria
3 Step oxidation (of pyruvate) process
– releases 1 CO2 (count the carbons!)
– reduces 2 NAD —>2 NADH (moves e-)
– produces acetyl CoA
Acetyl CoA enters __________
Krebs Cycle
Pyruvate oxidized to ___________
Acetyl CoA
- aka Citric Acid Cycle
– in mitochondrial matrix
– 8 step pathway - each catalyzed by specific enzyme
- step-wise catabolism of 6C citrate molecule
- Evolved later than glycolysis
– does that make evolutionary sense? - bacteria –>3.5 billion years ago (glycolysis)
- free O2 –>2.7 billion years ago (photosynthesis)
- eukaryotes –>1.5 billion years ago (aerobic
respiration = organelles ® mitochondria)
Krebs cycle
Krebs Cycle: Net Gain (Product)
= 2 ATP
= 6 NADH + 2 FADH2
If the yield is only 2 ATP then how was
the Krebs cycle an adaptation?
– value of NADH & FADH2
* electron carriers & H carriers
– reduced molecules move electrons
– reduced molecules move H+ ions
* to be used in the Electron Transport Chain
– series of molecules built into inner
mitochondrial membrane
* along cristae
* transport proteins & enzymes
– transport of electrons down ETC linked to
pumping of H+ to create H+ gradient
– yields ~34 ATP from 1 glucose!
– only in presence of O2 (aerobic respiration
Electron Transport Chain
Electron Carriers produced in Glycolysis and Krebs Cycle?
Glycolysis: 4 NADH
Krebs Cycle: 6 NADH and 2 FADH2
- The diffusion of ions across a membrane
– build up of proton gradient just so H+ could flow
through ATP synthase enzyme to build ATP
-links the Electron Transport Chain to ATP synthesis
Chemiosmosis
- Proposed chemiosmotic hypothesis
– revolutionary idea at the time
Peter Mitchell
What is the final
electron acceptor in
Electron Transport
Chain?
O2
So what happens if O2 unavailable?
- ETC backs up
>nothing to pull electrons down chain
>NADH & FADH2 can’t unload H
-ATP production ceases
-cells run out of energy
-and you die
– Break into AA’s
– Deaminate
– Alanine to pyruvate
– Glutamate to α
ketoglutarate
– Aspartate to oxaloacetate
Proteins
– Degrade into individual fatty acids &
glycerol
– Oxidized in matrix—enzymes attack
long fatty acid chains and remove 2C
chunks
– Entire chain is converted into acetyl-CoA
– Called Beta oxidation
– Glycerol is converted into pyruvate.
FATS
- When there is an excess of intermediates they
can be used to build necessary molecules. - Lipids can be generated from excess acetyl CoA
- Glycogen is generated from excess pyruvate
- Amino acids are generated from different
stages of the krebs cycle.
BIOSYNTHESIS
_____join the Krebs cycle at
different points
AA’s
_____can be generated from excess acetyl CoA
Lipids
______ is generated from excess pyruvate
Glycogen
