Cellular Respiration

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Transcript Cellular Respiration

Cellular Respiration
• The sum of all the chemical
processes occurring in an
organism at one time
• Concerned with the
management of material and
energy resources within the
• Reactions can break down big
molecules into smaller units
or build larger molecules from
smaller components
Anabolic (Biosynthetic)
• Pathways that consume
energy to build larger,
complicated molecules from
simpler ones
• Polymerization
• Photosynthesis
6CO2 +6H20 + light  C6H1206 + 6O2
• Carbon dioxide, a low energy
molecule, gets converted into
carbohydrate, a high energy
Catabolic Pathways
• Pathways that release energy
by breaking down complex
molecules into simpler
• Cellular respiration
• C6H1206 + 6O26CO2 +6H20 + ENERGY
• Carbohydrate, a high energy molecule,
gets “digested” into carbon dioxide, a low
energy molecule
• Cells use released energy to make ATP
Nucleotide with three
phosphate groups attached to
the ribose sugar
• Energy molecule used
to shuttle energy
between catabolic and
anabolic reactions
• Energy is released from
ATP through the loss of
phosphate groups
• Energy is released from ATP through the loss of
phosphate groups
• When ATP gives a phosphate group to another molecule it
is called phosphorylation
• Phosphorylated molecules have “more” energy and can do
the work of the cell
• How do we make ATP?
Cellular Respiration
What is cellular respiration?
Cellular Respiration : the making of ATP through
the breakdown of foods
• Aerobic Cellular Respiration
• Fermentation
Three Stages of
Aerobic Cellular Respiration
C6H1206 + 6O26CO2 +6H20 + ENERGY
• Aerobic cellular
respiration has 4 steps
– Glycolysis
• in cytosol
– Kreb’s cycle
• in mitochondrial matrix
– Electron Transport
• at inner membrane of
Structure of the Mitochondria
• Organelle with an outer
and inner membrane
• The Krebs cycle takes
place in the matrix of
the mitochondria
– space bordered by the
inner membrane
• Electron Transport
Chain takes place across
the inner membrane
– between the matrix and
intermembrane space
This organelle produces the
majority of ATP for the cell.
• This part of cellular respiration
takes place in the cell
• Each Glucose molecule gets
converted into 2 pyruvate
• Energy requiring and energy
releasing steps
• Energy net yield is 2 ATP and
• Enzymes help along the way
Krebs Cycle
• Each pyruvate
molecule is
completely oxidized
into carbon dioxide
• Energy released from
these reactions results
in the formation of 1
ATP molecule but 3
NADH molecules
Collectively, 2 ATP and 6 NADH
are made from the 2 pyruvates.
NADH will be used in the electron
transport chain.
Electron Transport Chain
• During the electron
transport chain, H+ is
moved against a
• The energy needed to
do this is supplied by
electrons carried by
What happens along the inner
membrane of the mitochondria?
• The loss of electrons from
NADH result in the
addition of energy to
protein pumps in the
memebrane resulting in a
H+ being moved from the
inside to the outside of the
inner membrane
• This happens many times
creating an imbalance
Oxygen pulls electrons to
(gradient) of H+.
keep them moving.
What happens along the inner
membrane of the mitochondria?
• ATP is made as H+ ions are
allowed back into the matrix
of the mitochondria by a
different protein (ATP
• The energy released by the
“rush” of H+ is used by this
enzyme to make ATP (kind
of like a rush of water in a
Ultimately, aerobic respiration
stream being used to turn a
produces ~36 ATP molecules
water wheel).
from each individual
glucose molecule.
Why do we need oxygen?
• Oxygen is required by any organism that has
mitochondria because it is used to keep the
Electron Transport Chain running
• Oxygen pulls of electrons from the chain and
combines with 2 H+ to form H20
What if we did not have oxygen?
• Without trees and
bacteria to make
oxygen, we would still
be able to make ATP
from sugar (just not as
• Modifications of
glycolysis called
fermentation reactions
are used to release
Fermentation Reactions
• These reactions
produce only 2 ATP
per glucose molecule
and must regenerate
NAD+ resulting in the
formation of either:
1 Ethanol and CO2 or
2 Lactic Acid
What about other foods?
• Proteins, Carbs and Fats can all be utilized for energy following
• Amino Acids are converted to intermediates including pyruvate,
2-, and 4-carbon molecules
• Carbs enter glycolysis at the beginning or in the middle
• Fats components
– glycerol enters as 3-carbon molecule
– Fatty acids enter as 2-Carbon molecules