Cellular Respiration

download report

Transcript Cellular Respiration

Cellular Respiration
Glycolysis
Krebs cycle
Electron transport
Learning check
This figure represents an
overview of the different
processes of cellular
respiration.
Which of the following correctly identifies the different
processes?
a) 1. Glycolysis; 2. Electron transport chain; 3. Krebs cycle
b) 1. Glycolysis; 2. Krebs cycle; 3. Electron transport chain
c) 1. Krebs cycle; 2. Electron transport chain; 3. Glycolysis
d) 1. Electron transport chain; 2. Glycolysis; 3. Krebs cycle
What would
happen to the flow
of electrons if
oxygen were not
present?
a. The flow of electrons would continue but at a slower rate.
b. The flow would cease and ATP production would stop.
c. The presence of oxygen would have no effect.
Cyanide binds strongly
with the last electron
carrier in the chain.
How would this affect
the flow of electrons?
a. The flow of electrons would continue but at a slower rate.
b. The flow would cease and ATP production would stop.
c. The presence of cyanide would have no effect.
How many ATPs?
Cell Respiration Overview
Glucose:
Stores energy in the molecule
Cell respiration:
• Breaks down the molecules
• Extracts the contained energy
• Transfers electrons (from glucose)
• To hydrogen carriers (e.g., NADH)
• And to make ATP
• Giving off waste products (CO2 & H2O)
1st stage:
Cytoplasm
2nd & 3rd stage:
Mitochondria
1st stage:
Glycolysis
2nd stage:
Krebs cycle
(or citric acid)
3rd stage:
Electron
transport
Glycolysis, in the cytoplasm
Series of steps (but 2 phases)
1. Glucose
2 pyruvic acid molecules
As bonds in glucose are broken
2. Electrons (and H+ ions)
NAD+
NADH
Glucose
Is oxidized
NAD+
Is reduced
Net output is 2 ATP for each glucose molecule
But, most of the released energy carried by NADH
Glucose
2 pyruvic acids
Phase one
3 carbon
6 carbon
3 carbon
Glycolysis, phase 1
Some ATP is used to start the ‘breakdown’ of glucose
Mitochondria
Cytoplasm
View Activity: Glycolysis
Glycolysis, phase 2
High energy electrons are donated
To NAD+
Forming
NADH
Glycolysis, phase 2
And, phosphate groups are transferred
ATP is made
In-between glycolysis & Krebs
Just before (or as) they enter the mitochondria
Pyruvic acid molecules are modified
And CO2 is released
The altered molecule is acetic acid (…vinegar!)
Acetic acid is attached to a carrier molecule
Called coenzyme A
And forms acetyl CoA
To the mitochondrion
Learning check
7
3
4
2
1
6
8
5
1.
2.
3.
4.
Name molecule
Name molecule
Name molecule
Name the reaction
5.
6.
7.
8.
9.
Name of molecule
What does the arrow refer to?
Name of molecule
Name of molecule
Where does this take place?
Krebs cycle, in the mitochondria
Series of reactions
Continues to break down the sugar
Present as acetic acid
Captures more energy
As NADH & FADH2
And more CO2 is released
Net output is 2 ATP for each glucose molecule
But again, most of the released energy carried by NADH
Krebs (citric acid) cycle & energy production
Citric acid
Fuel: Acetic acid
3
Waste: 2 CO2
3
Acceptor molecule
View Activity: The Citric Acid Cycle
Electron Transport,
in the mitochondria
Most of the ATP is produced in the ET
And, NADH & FADH donate their electrons to the ET
At the end of the chain of steps
O2 exerts a strong pull on electrons
And combines electrons & H+ ions to form H2O
The ‘downhill’ flow of electrons powers an enzyme
ATP synthase
Which produces ~ 34 ATP
Electron Transport
An array of molecules
(…proteins)
In the inner membrane of the mitochondrion
View Activity: Electron Transport
Electrons move from one member to the next
The energy given up pumps H+ to inner space
Matrix
Oxygen captures electrons
Hydrogens are added, water forms
The buildup of H+ ions give up energy
When they diffuse through a special protein
Matrix
ATP synthase
ATP synthase captures their energy
To make ATP
Learning check, name the numbered parts
How many?
4
15
10
11
7
1
2
6
3
9
14
12
8
13
5
18
16
17
Learning check
1. Of the 3 stages of cell respiration, which
produces the most ATP per glucose?
2. In glycolysis, _______ is oxidized and _______
is reduced.
3. The final electron acceptor of the electron
transport chains in mitochondria is _______.
Learning check
4. Cells can harvest the most chemical energy
from which of the following?
a. An NADH molecule
b. A glucose molecule
c. Six carbon dioxide molecules
d. Two pyruvic acid molecules