Download Glycolysis is the first stage of respiration!

Cell Respiration
Cellular Respiration
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To perform their many
tasks cells require
transfusions of energy
from outside sources
Energy enters ecosystems
as sunlight, the energy
source for plants and
other photosynthetic
organisms
Animals obtain energy by
eating plants or by eating
organisms that eat plants
Cellular Respiration
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During cellular respiration organic
compounds are broken down using
oxygen as a reactant
Organic compounds + oxygen
carbon dioxide + water + energy
Cellular Respiration
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Respiration is a stepwise redox (reduction/oxidation) reaction
Recall: a redox reaction is a transfer of one or more electrons from
one reactant to another
oxidation
Na + Cl2
NaCl
reduction
Cellular Respiration:
oxidation
C6H12O6 + 6O2
6CO2 + 6H2O + energy
reduction
Cellular Respiration
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Energy is not liberated all at once (explosion!)
Glucose is broken down gradually
Hydrogen atoms and electrons are stripped from
glucose and are passed to a coenzyme called
nicotinamide adenine dinucleotide (NADH)
Eventually electrons are passed to oxygen in a
series of steps called the electron transport
chain
NAD+ is an oxidizing agent
C
OH + NAD+
Oxidized
form
C
O + NADH
Reduced
form
Three Stages of Respiration
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The three main stages are:
1) Glycolysis
2) Krebs cycle (citric acid cycle)
3) electron transport and oxidative
phosphorylation
Glycolysis takes place in the cytoplasm
Krebs cycle and electron transport take
place in the mitochondria
Mitochondria
Found in nearly all eukaryotic cells
In animal cells they are oval
Cristae increase surface area and are the
site of electron transport
The matrix is like the cytoplasm of cells
where enzymatic reactions take place
Glycolysis
The first stage of respiration
Respiration
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Process of respiration
is split into three
stages and the link
reaction
Glycolysis is the first stage of respiration!
Glycolysis is the first stage of respiration!
Glycolysis splits one molecule of glucose
into two smaller molecules of pyruvate
Glycolysis is the first stage of respiration!
Glycolysis splits one molecule of glucose
into two smaller molecules of pyruvate
Glucose is a hexose
(6-carbon) molecule
Glycolysis is the first stage of respiration!
Glycolysis splits one molecule of glucose
into two smaller molecules of pyruvate
Pyruvate is a triose
(3-carbon) molecule
Glucose is a hexose
(6-carbon) molecule
Glycolysis is the first stage of respiration!
Glycolysis splits one molecule of glucose
into two smaller molecules of pyruvate
Pyruvate is a triose
(3-carbon) molecule
Pyruvate is also
known as pyruvic
acid
Glucose is a hexose
(6-carbon) molecule
• Glycolysis takes place in the
cytoplasm of cells.
• Glycolysis takes place in the
cytoplasm of cells.
• It’s the first stage of both
aerobic and anaerobic
respiration.
• It’s the first stage of both
aerobic and anaerobic
respiration.
•It doesn’t need oxygen to take
place – so it’s anaerobic
• It’s the first stage of both
aerobic and anaerobic
respiration.
•It doesn’t need oxygen to take
place – so it’s anaerobic
There are TWO STAGES of GLYCOLYSIS –
Phosphorylation and Oxidation
Glycolysis
Stage One - Phosphorylation
Stage One - Phosphorylation
1. Glucose is phosphorylated by
adding 2 phosphates from 2
molecules of ATP to give a hexose
phosphate.
Stage One - Phosphorylation
1. Glucose is phosphorylated by
adding 2 phosphates from 2
molecules of ATP to give a hexose
phosphate.
2. The hexose phosphate is split
using water
Stage One - Phosphorylation
1. Glucose is phosphorylated by
adding 2 phosphates from 2
molecules of ATP to give a hexose
phosphate.
2. The hexose phosphate is split
using water (hydrolysis)
Stage One - Phosphorylation
1. Glucose is phosphorylated by
adding 2 phosphates from 2
molecules of ATP to give a hexose
phosphate.
2. The hexose phosphate is split
using water (hydrolysis)
3. 2 molecules of triose phosphate
and 2 molecules of ADP are
created.
A triose phosphate is just a simple 3-carbon sugar
with a phosphate group attached.
Different books use different names!
Glyceraldehyde 3phosphate (G3P)
What’s the point?
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Glucose can now no
longer leave the cell.
What’s the point?
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Glucose can now no
longer leave the cell.
Molecules produced
are much more
reactive!
Glyceraldehyde 3phosphate
Stage Two - Oxidation
Stage Two - Oxidation
1. The triose phosphates are
oxidised (lose oxygen), forming
two molecules of pyruvate.
Stage Two - Oxidation
1. The triose phosphates are
oxidised (lose oxygen), forming
two molecules of pyruvate.
2. Coenzyme NAD+ collects the
hydrogen ions, forming 2 reduced
NAD (NADH + H+)
Stage Two - Oxidation
1. The triose phosphates are oxidised (lose
oxygen), forming two molecules of pyruvate.
2. Coenzyme NAD+ collects the hydrogen ions,
forming 2 reduced NAD (NADH + H+)
A coenzyme is a helper molecule
that carries chemical groups or ions,
e.g. NAD+ removes H+ and carries it
to other molecules.
Stage Two - Oxidation
1. The triose phosphates are
oxidised (lose oxygen), forming
two molecules of pyruvate.
2. Coenzyme NAD+ collects the
hydrogen ions, forming 2 reduced
NAD (NADH + H+)
3. 4 ATP are produced, but 2 were
used up at the beginning, so
there’s a net gain of 2 ATP.
Next in Aerobic respiration….
Next in Aerobic respiration….
1. The 2 molecules of reduced NADH
go to the electron transport chain
(ETC), part 4 of respiration.
Next in Aerobic respiration….
1. The 2 molecules of reduced NAD go
to the electron transport chain
(ETC), part 4 of respiration.
2. The two pyruvate molecules go into
the matrix of the mitochondria for the
link reaction.
The Link Reaction
The Link Reaction
The second stage of
respiration
You are now in
the matrix of the
mitochondria!
Link Reaction – 2nd stage of respiration
Link Reaction – 2nd stage of respiration
The Link Reaction converts Pyruvate
to Acetyl Coenzyme A
Link Reaction – 2nd stage of respiration
The Link Reaction converts Pyruvate
to Acetyl Coenzyme A
The link reaction happens when
oxygen is available.
Link Reaction – 2nd stage of respiration
Link Reaction – 2nd stage of respiration
1. One carbon atom is
removed from pyruvate in
the form of CO2.
Link Reaction – 2nd stage of respiration
1. One carbon atom is
removed from pyruvate in
the form of CO2.
2. The remaining 2-carbon
molecule combines with
coenzyme A to produce
acetyl coenzyme A
(acetyl CoA).
Link Reaction – 2nd stage of respiration
1. One carbon atom is
removed from pyruvate in
the form of CO2.
2. The remaining 2-carbon
molecule combines with
coenzyme A to produce
acetyl coenzyme A
(acetyl CoA).
3. Another oxidation reaction
happens when NAD+
collects more hydrogen
ions. This forms reduced
NAD (NADH + H+).
Link Reaction – 2nd stage of respiration
4. No ATP is produced in
this reaction.
Link Reaction – 2nd stage of respiration
The Link reaction happens Twice for
every Glucose Molecule
Link Reaction – 2nd stage of respiration
The Link reaction happens Twice for
every Glucose Molecule
So for every glucose molecule used in
glycolysis, two pyruvate and two acetyl
CoA molecules are made.
So for each glucose molecule:
So for each glucose molecule:
•Two molecules of acetyl CoA go into
Krebs cycle (part 3 of respiration)
So for each glucose molecule:
•Two molecules of acetyl CoA go into
Krebs cycle (part 3 of respiration)
So for each glucose molecule:
•Two molecules of acetyl CoA go into
Krebs cycle (part 3 of respiration)
•Two carbon dioxide molecules are
released as a waste product of respiration
So for each glucose molecule:
•Two molecules of acetyl CoA go into
Krebs cycle (part 3 of respiration)
•Two carbon dioxide molecules are
released as a waste product of respiration
•Two molecules of reduced NAD are
formed and go into the electron
transport chain (part 4 of respiration)
So for each glucose molecule:
•Two molecules of acetyl CoA go into
Krebs cycle (part 3 of respiration)
•Two carbon dioxide molecules are
released as a waste product of respiration
•Two molecules of reduced NAD are
formed and go into the electron
transport chain (part 4 of respiration)