Global warming
Since the last ice age, carbon dioxide levels have increased
continually. The increase of carbon dioxide over the last 150 years
has been much more dramatic going from 280 parts per million
(PPM) to 400 PPM. This has had obvious effects on the global
temperature averages as the ten hottest years on record occurred
from 1998 to now. The ten hottest years ever were:
1. 2010
2. 2005
3. 1998
4. 2013
5. 2003
6. 2002
7. 2006
8. 2009
9. 2007
10. 2004
Cellular Energetics
How cells obtain and use energy
through the processes of
photosynthesis and cellular
respiration
IV. Cellular Energetics
A.
Energy - ability to do work
1.
2.
Cells use an energy-storing compound known as
ATP to provide the energy to do work
ATP = Adenosine Triphosphate
a.
b.
c.
d.
e.
Energy is stored in the bonds between phosphate
groups
Energy is released when bonds are broken
ATP becomes ADP when a phosphate is lost
ATP is recyclable
Cells regenerate ATP through the process of cellular
respiration which is reliant on photosynthesis
Sunlight energy
ECOSYSTEM
Photosynthesis
in chloroplasts
CO2
Glucose
+
+
H2O
O2
Cellular respiration
in mitochondria
ATP
(for cellular work)
Heat energy
3.
Obtaining energy
a.
Autotrophs – organisms capable of using a source of
energy to produce food molecules from inorganic
molecules in the environment
i. Photoautotrophs – capture light energy
ii. Chemoautotrophs – absorb other inorganic molecules to
produce own food
b.
Heterotrophs – organisms that obtain energy from the
consuming of other organisms
B. Cellular Respiration
1.
2.
3.
4.
Autotrophs and heterotrophs must be able to release energy
from the carbohydrates produced during photosynthesis
During cellular respiration, glucose is broken down in a stepby-step process to release the energy stored in its bonds
The energy from the breakdown of glucose is used to
generate ATPs
Chemical equation
C6H12O6 + 6O2 ----> 6CO2 + 6 H2O + ENERGY (ATP)
5. Occurs in the cytoplasm and the mitochondrion
NADH
High-energy electrons
carried by NADH
NADH
FADH2
and
OXIDATIVE
PHOSPHORYLATION
GLYCOLYSIS
Glucose
CITRIC ACID
CYCLE
Pyruvate
(Electron Transport
and Chemiosmosis)
Mitochondrion
Cytoplasm
CO2
CO2
ATP
ATP
Substrate-level
phosphorylation
Substrate-level
phosphorylation
ATP
Oxidative
phosphorylation
6.
Reactions
a. Glycolysis
i. Takes place in the cytoplasm
ii. The initial splitting of a glucose molecule
iii. Produces two pyruvates
iv. Process requires energy (2 ATP) to break apart glucose and
produces 4 ATP
v. Breaking of bonds releases energized electrons which are
accepted by a molecule known as NAD+
vi. NAD+ is converted to NADH to carry electrons to the electron
transport chain in the mitochondrion
vii. If oxygen is present, the pyruvates can enter the mitochondrion
(aerobic)
viii. If oxygen is absent, the pyruvates will remain in the
cytoplasm (anaerobic)
b. Krebs Cycle
i. Takes place in the mitochondrion
ii.Two pyruvates enter the mitochondrion and are further broken
down to release energy
iii. As pyruvate is gradually broken down, carbon dioxide is
released as a waste product and released electrons are accepted
by more NAD+ and an additional molecule known as FAD
iv. Produces 1 ATP for every cycle (2 ATP total)
c. Electron Transport Chain
i. Takes place in the inner mitochondrial membrane
ii. Energized electrons from the broken bonds of glucose and pyruvate
provide the energy to produce ATPs
iii. NADH and FADH2 transfer electrons to an ETC in the inner
mitochondrial membrane
iv. Energy from the electrons activates proton pumps, building a
proton concentration gradient across the membrane
v. Protons pass through ATP synthase, a tranport protein/enzyme that
produces ATP
vi. As protons pass through, ADP is converted into ATP
vii. Produces up to 34 ATP
d. Overall process produces a total of 36 – 38 ATP
H+
Intermembrane
space
.
H+
H+
H
H+
Protein
complex
H+
+
H+
H+
H+
Electron
carrier
ATP
synthase
Inner
mitochondrial
membrane
FADH2
Electron
flow
NAD+
NADH
Mitochondrial
matrix
FAD
H+
1
O 2 + 2 H+
2
H+
H+
H2O
Electron Transport Chain
OXIDATIVE PHOSPHORYLATION
ADP +
ATP
P
H
+
Chemiosmosis
Rotenone
Oligomycin
Cyanide,
carbon monoxide
H+
H+
H+
H+
H+
+
H
+
H
H+
+
H
ATP
Synthase
DNP
FADH2
FAD
1
NAD+
NADH
2
+
O2 + 2 H
H+
H+
H2O
ADP + P
ATP
H+
Electron Transport Chain
Chemiosmosis
7. Fermentation - Breaking down glucose without oxygen
a.
b.
c.
d.
e.
f.
Occurs in the cytoplasm
Otherwise known as anaerobic respiration
Begins with glycolysis
Only produces 2 ATP
Purpose is to regenerate NAD+
Two types
i.
Lactic acid fermentation
A. Pyruvate is converted into lactic acid
B. Occurs in muscle cells
ii. Alcoholic fermentation
A. Pyruvate is converted to ethyl alcohol
B. Occurs in yeast cells
C. Photosynthesis
1.
2.
Conversion of sunlight energy into chemical energy
stored in the bonds of carbohydrates and other organic
molecules
Chemical equation
light
6CO2 + 6H2O ----> C6H12O6 + 6O2
3. Occurs in the chloroplast
a. Thylakoid – photosynthetic membrane disk
b. Granum – stack of thylakoids
c. Stroma – space between the thylakoids and the outer
membranes of the chloroplast
4. Pigments – substance capable of absorbing and
reflecting light energy
a. Chlorophylls – primary pigment
b. Carotenoids
c. Xanthophylls
5. Reactions
a. Light reactions
i.
Capture of sunlight energy to produce temporary energystoring compounds (ATP and NADPH)
ii.
Occurs in the thylakoids
iii.
Light is absorbed by photosystems – clusters of pigment
molecules in the thylakoids
iv.
Electrons in pigment molecules are “excited” to higher
energy levels
Reactions
5.
a.
Light reactions
v. “Excited” electrons are passed along a series of membrane proteins
known as the electron transport chain (ETC) in the thylakoid
membrane
vi. Energy from electrons is used to generate ATP
- Energy from the electrons activates proton pumps, building a proton
concentration gradient as hydrogen ions (protons) are pumped across
the membrane
- Protons pass through ATP synthase, a transport protien/enzyme that
produces ATP
- As protons pass through, ADP is converted into ATP
vii. Electrons are eventually passed to an energy-storing molecule known
as NADPH
viii. Water is split to replenish electrons in pigment molecules
ix. As water splits, electrons are donated to chlorophyll and oxygen gas is
released
5.
Reactions
b. Dark reactions
i. Otherwise known as the Calvin Cycle
ii. Energy from the ATP and NADPH produced in the light
reactions is used to produce organic molecules from carbon
dioxide
iii. Occurs in the stroma