Download Cellular Energy

Chapter 8
Main Ideas:
1. All living organisms use energy to carry out all biological processes.
2. Light energy is trapped and converted into chemical energy during
photosynthesis.
3. Living organisms obtain energy by breaking down organic molecules during
cellular respiration
Cellular Energy
I. HOW ORGANISMS OBTAIN ENERGY
A. Why do we need energy? What are some of the things that energy
allows us to do?
B. Everything we do requires energybreathing, heartbeat, cell division
1. energy
C. Transformation of Energy
1. Thermodynamics
a. 1st law of thermodynamics
1.
when we eat we consume stored energy that is converted to
chemical energy & used as mechanical energy
b. 2nd law of thermodynamics
1.
the lost energy is generally heat
2.
entropy
3.
therefore 2nd law could also state entropy increases
4.
foodchains
2. Autotrophs & Heterotrophs
a. all organisms req energy
b. source=
1.
autotrophs
2.
heterotrophs
D. Metabolism
1.
2. metabolic pathway
a. catabolic pathway
b. anabolic pathway
c. both pathways result in the continual flow of energy w/i an
organism
3. photosynthesis
a. autotrophs use light energy, CO2, & H2O to make glucose & O2
b. energy in the glucose is used when the autotroph is consumed
4. cellular respiration
a. O2 is used to breakdown organic moleculesCO2 & H2O
E. ATP: The Unit of Cellular Energy
1. energy exists in many forms
2. for living organisms chemical energy is stored in biological molecules &
it’s converted to usable forms when needed
3. adenosine triphosphate (ATP)
a. most abundant energy carrying molecule in cells & it’s in all types
of organisms
b. nucleotide
c. ATP
1.
this forms adenosine diphosphate (ADP) & a free phosphate grp
2.
3.
the phosphates all have the same charge
4.
recall that like charges will repel each other
5.
6.
adenosine monophosphate is another energy molecule, but w/less
energy
7.
why is there less energy as the number of phosphate grps
decrease?
II. PHOTOSYNTHESIS
A.
1.
B. 2 phases
1.
a.
2.
3.
C. Phase I: Light Reactions
1.
D. Chloroplasts & Pigments
1. chloroplasts
a.
b
1.
thylakoids
2.
grana
c.
d. stroma
2. Pigments
a. thylakoid membranes contain pigments
b. chlorophyll
III. STEPS IN THE LIGHT DEPENDENT RXNS (LDR)
A. First phase of photosynthesisPhotosystems I & II
B. PHOTOSYSTEM I & II
1. sunlight strikes the chlorophyll in the thylakoid membranes
a.
b. light energy also splits a molecule of H2O
1.
an electron goes to the electron transport chain (ETC)
2.
a H+ ion (called a proton) that goes to the thylakoid space
3.
O2 is released as waste
2. electrons leave the chlorophyll & enter the electron transport chain
(ETC)
a.
b. the energized electrons are passed from protein to protein to
photosystem I
c. in the presence of light photosystem I transfers the electrons to
ferrodoxin
d. ferrodoxin transfers the electrons to an electron carrier
1.
NADP+
2.
3.
3. Chemiosmosis
a.
4. Water’s Importance
a.
b.
c. photolysisthe splitting of water molecules; produces 1.5 O, 2
electrons, & 2 H+
d. O is released to ATMS & electrons go to chlorophyll
e.
f.
IV. LIGHT INDEPENDENT RXNS
A.
B.
1.
2.
3.
C. Steps in the Calvin Cycle
1. 1st stepcarbon fixation
a. 6 CO2 molecules combine w/ 6 5-carbon compounds to form 12
3-carbon compounds called 3-PGA (3-phosphoglycerate)
b. 2nd stepenergy stored in ATP & NADPH from the LDR is
transferred to the 3-PGA molecules to make 3-PGAL
(glyceraldehyde 3-phosphate)
c. ATP supplies the phosphate grps & NADPH supplies H+ & electrons
d. 3rd step2 PGAL leave the cycle to make glucose & other organic
compounds
e. final steprubisco (enzyme) converts the remaining 10 PGAL into
RuBP (ribulose 1, 5-biphosphate)
D. Alternative Pathways
1. C4 plants
a. sugarcane & corn
b. fix CO2 into 4-carbon compounds instead of 3-carbon compounds
c. keep stomata closed on hot days4-carbon compounds get
transferred to special cells where CO2 enters the Calvin cycle; this
minimizes H2O loss
2. CAM plants
a. crassulacean acid metabolism (CAM photosynthesis)
b. H2O conserving plants
c. CO2 enters the leaves only at nightcooler & more humid
d. CO2 dioxide is fixed into organic compounds at night & during the
day CO2 is released & enters the Calvin cycle
e. minimizes H2O loss
V. CELLULAR RESPIRATION
A. process by which mitochondria break down food molecules to produce
ATP
1. ATP is used by the cells to do work
2. C6H12O6 + 6O26CO2 +6H2O + ENERGY
B. 2 parts
1.
a. anaerobic
2. aerobic respiration
a.
b.
C. Glycolysis
1.
a. requires 2 ATP to start glycolysis, but only 4 ATP are produced
b. therefore glycolysis is not efficient
c.
2.
3.
a.
D. Citric Acid Cycle
1. also known as the Krebs Cycle
2. in the presence of O2 pyruvate is transported into the mitochondrial
matrixconverted to CO2
3.
a. electron carriers
4. Krebs cycle steps
a.
b
c.
d.
e.
E. Electron Transport Chain
1.
2.
a. electrons are passed from protein to protein in the mitochondrial
membrane
3. H+ get pumped into the mitochondrial matrix & then diffuse down a
concentration gradient
a. H+ go thru ATP synthaseprod 32 ATP
4.
a.
5.
6.
F. Anaerobic Respiration
1. some cells can prod ATP when O2 levels are low
a. problem=
2. fermentation/anaerobic respiration
3. 2 types
4.
a.
b.
c.
d.
5.
a.
b.