Transcript Energy represents the capacity to do work. Cells must

Ch.8 – Cellular Energy
8.1 – How organisms obtain energy
Energy represents the capacity to do work.
Cells must acquire energy from their environment.
In life, energy transformations consist primarily of movement of
molecules and changes in chemical bonds.
Metabolism
is the set of chemical reactions that
happen in living organisms to maintain life
2 Types
Catabolism
Releasing energy by
breaking down of
larger molecules into
smaller ones
Digestion
Anabolism
Storing energy by
creating larger
molecules from
smaller ones.
Creating body fat
Ch.8 – Cellular Energy
8.1 – How organisms obtain energy
All living cells use adenosine triphosphate (ATP) for
capture, transfer, and storage of energy.
Each cell
needs millions
of ATP
molecules per
second in order
to drive its
biochemical
machinery
Ch.8 – Cellular Energy
8.1 – How organisms obtain energy
Autotrophs
are able to create glucose
from inorganic substances.
That glucose is broken down
to form ATP molecules
Autotrophs
Heterotrophs
Heterotrophs
obtain glucose from
digesting other living
things.
That glucose is
broken down to form
ATP molecules
Ch.8 – Cellular Energy
8.2 – Photosynthesis
The story of how living things make ATP starts with…
Carbon Dioxide + Water Light Glucose + Oxygen
6 CO2 + 6 H2O Light C6H12O6 + 6 O2
Ch.8 – Cellular Energy
8.2 – Photosynthesis
Ch.8 – Cellular Energy
8.2 – Photosynthesis
3PGA
Glucose
Ch.8 – Cellular Energy
Light Reaction Movie
8.2 – Photosynthesis
Ch.8 – Cellular Energy
8.2 – Photosynthesis
Photosystem II
• Light energy is used to split
an H2O molecule
• When H2O splits
- O2 is released
- protons (H+ ions) stay in
the thylakoid space &
- an activated electron
enters the electron
transport chain.
Ch.8 – Cellular Energy
8.2 – Photosynthesis
Electron Transport Chain
Electrons are moved through
the thlakoid membrane and
more protons are pumped
into the thylakoid space
Ch.8 – Cellular Energy
Photosystem I
•Light reenergizes the
electrons
•The reenergized electon is
transferred to
NADP+ Reductase to form an
NADPH from NADP+
8.2 – Photosynthesis
Ch.8 – Cellular Energy
8.2 – Photosynthesis
Chemiosmosis
• Protons build up in the thylakoid space and create a
concentration gradient
• Protons then move across the thylakoid membrane
through ATP synthase which causes ADP to convert
to ATP
Light Reactions Animation
8.2 – Photosynthesis
1. What is the basic formula of photosynthesis?
Ch.8 – Cellular Energy
2. How did plants acquire photosynthesis in evolution?
Name three features of chloroplasts that are
indicative of their origin. (It is referred to as
endosymbiosis or the endosymbiotic theory) Click
3. Photosynthesis can be divided in two different
processes. What are these processes? What are
their products and reactants?
4. Oxygen is released during photosynthetic light
reactions. Where is this oxygen coming from?
The splitting of H2O in Photosystem II
Ch.8 – Cellular Energy
8.2 – Photosynthesis
5. What is the driving force for ATP synthesis at the
ATP synthase multi-protein complex?
6. Where do you find a higher pH value, inside or
outside of the thylakoid?
7. Which process creates NADPH from NADP+?
Photosystem I
Energized e- are transferred to the enzyme
NADP+ Reductase
Ch.8 – Cellular Energy
8.2 – Photosynthesis
Ch.8 – Cellular Energy
8.2 – Photosynthesis
The Calvin Cycle (light independent reactions or the dark reactions)
3PGA
Glucose
Ch.8 – Cellular Energy
8.2 – Photosynthesis
Carbon Fixation
3 CO2 combine with 3 5-C compounds
to form 6 3-C compounds called
3-PGA
Ch.8 – Cellular Energy
8.2 – Photosynthesis
Reduction
Energy from ATP and
NADPH is used to
form
6 G3P molecules
(high energy molecules)
From the 6 PGA
molecules
1 G3P molecule leaves
the cycle to form
glucose, fructose
starches, etc.
Ch.8 – Cellular Energy
8.2 – Photosynthesis
Regeneration
ATP and the enzyme
rubisco convert the 5
G3P to 3 RuBP
These molecules are
then ready to bond
with 3 more CO2
Calvin Cycle Animation
Ch.8 – Cellular Energy
8.3 - Cellular respiration
Cellular Respiration
Aerobic Respiration
requires O2 to make ATP
from the energy stored
in glucose
Glucose + Oxygen  Energy + Carbon Dioxide + Water
C6H12O6 + 6 O2  36/38 ATP + 6 CO2 + 6 H2O
Ch.8 – Cellular Energy
8.3 - Cellular respiration
8.3 - Cellular respiration
The 3 Processes of cellular respiration
Ch.8 – Cellular Energy
O2
2
3
1
Electron
Transport Chain
Oxidative
phosphorylation
or Krebs Cycle
H2O
CO2
2
2
32
Or
34
Ch.8 – Cellular Energy
• Glycolysis
(“splitting of sugar”) breaks
down glucose into two
molecules of pyruvate
• Glycolysis occurs in the
cytoplasm and has two
major phases:
-Energy investment phase
-Energy payoff phase
Net ATP = 2
8.3 - Cellular respiration
Ch.8 – Cellular Energy
Citric Acid Cycle or
Krebs Cycle
Before the citric acid
cycle can begin,
pyruvate must be
converted to
Acetyl CoA
It takes place in the
matrix of the
mitochondria
8.3 - Cellular respiration
Ch.8 – Cellular Energy
Citric Acid Cycle or
Krebs Cycle
The acetyl group of
acetyl CoA joins the
cycle by combining
with the 4-C
compound,
oxaloacetate,
forming citric acid
(citrate)
8.3 - Cellular respiration
Ch.8 – Cellular Energy
Citric Acid Cycle or
Krebs Cycle
The next seven steps
decompose the citrate
back to oxaloacetate
The NADH and FADH2
produced by the cycle
send electrons to the
electron transport chain
8.3 - Cellular respiration
Ch.8 – Cellular Energy
8.3 - Cellular respiration
•e- from NADH & FADH2 pass through protein
complexes in the cristae (inner membrane)
•This causes H+ to be pumped out of the matrix
Ch.8 – Cellular Energy
8.3 - Cellular respiration
•O
the matrix
bonds
the e- to
To2 diffuses
give youinto
an idea
of howand
much
ATPwith
we require
passing through the transport
survive…chain.
+ diffuses
•H
through
back
thebreath
We
take in about
2 xATP
1020synthase
molecules
of Ointo
2 per
matrix (chemiosmosis)
creating ATP (phosphorilation)
200,000,000,000,000,000,000
8.3 - Cellular respiration
Making energy when there is no oxygen
Anaerobic Respiration or
Fermentation
Ch.8 – Cellular Energy
It is essentially a cell just relying on glycolysis for its
energy needs
Only produces 2 ATP per glucose molecule (not the
36 or 38 that aerobic respiration can create)
Other molecules are created through reactions that
provide the NAD+ needed for glycolysis to occur
ATP can be created much faster than with aerobic
respiration (just in smaller quantities)
Glucose
2 ATP
=O
-O
CH3-C-C-OH
2 Pyruvic Acids
Alcoholic
Fermentation
-O
Lactic Acid
Fermentation
4 ATP
=O
-OH
CH3-CH
2 Acetylaldehydes
CH3-CH-C-OH
2 Lactic Acids
CH3-CH2-OH
2 Ethanols
Glucose
2 ATP
=O
-O
Lactic Acid
Fermentation
4 ATP
CH3-C-C-OH
2 Pyruvic Acids
=O
-OH
•Used by some fungi and
bacteria & is used to
make cheese and yogurt
CH3-CH-C-OH
2 Lactic Acids
•Human muscle cells use
lactic acid fermentation to
generate ATP when O2 is
scarce
Glucose
2 ATP
=O
-O
Lactic Acid
Fermentation
4 ATP
CH3-C-C-OH
2 Pyruvic Acids
=O
-OH
•Used by some fungi and
bacteria & is used to
make cheese and yogurt
CH3-CH-C-OH
2 Lactic Acids
•Human muscle cells use
lactic acid fermentation to
generate ATP when O2 is
scarce
Glucose
2ATP
CH3-C-C-OH
2 Pyruvic Acids
Used by yeast and
some bacteria & is
used in brewing,
winemaking, and
baking
Alcoholic
Fermentation
-O
=O
-O
4ATP
CH3-CH
2 Acetylaldehydes
CH3-CH2-OH
2 Ethanols