Transcript Plants

Photosynthesis
I. The basics
A. The equation
6CO2 + 6H2O  C6H12O6 + 6O2
1. CO2
a. pulled from the air thru the
stomate
b. reduced to -CHO
2. H2O
a. enters the plant thru the
roots  xylem  all parts
b. oxidized to oxygen
c. transpiration
-evaporation of water at the
leaves….
3. C6H12O6
a. used in Cellular Respiration to
make ATP
-C is bond to O2 make CO2
b. excess sugar is stored as
STARCH in clusters within the
plant:
-Cells of fruit
-seeds
-stems
-modified roots
-converted to oil & stored in seeds
c. 250,000 known spp. of plants of
which ~150 are cultivated
-crops: a type of plant that is
grown for use by humans
-3 Major crops that feed the
world:
4. O2
a. exits thru the stomate
b. important byproduct for
living org
B. Leaf Structure
1. PS occurs in the __________
2. Chloroplast has 2 main parts:
a. thylakoid…
-flattened membrane-bound sacs
-sacs are stacked into ______
-chlorophyll is embedded here
b. stroma…
-fluid matrix of the chloroplast
-contains enzymes…
C. How is light Energy used?
1. Light is radiant Energy
a. can travel in waves
b. electromagnetic spectrum
-complete range of radiant E
c. photons
-tiny packets of E
d. visible light spectrum
- ROY G BIV
Longer λ
Shorter λ
2. Light hitting a surface
a. the photons are either:
(1) reflected
(2) absorbed
(3) transmitted thru the object
b. the color of the plant is the
color being reflected….
D. Pigments in plants
1. Pigment
a. a molecule containing atoms that
enable it to absorb light
2. Chlorophyll a
a. primary pigment
b. absorbs violet and orange/reds
c. reflects green light
3. accessory pigments
a. chlorophyll b
b. xanthophyll
-reflects yellow
c. carotenoids
-reflects orange
d. each pigment absorbs diff
wavelengths of light…Advantage?
e. changing of leaves in the Fall
4. Pigments are arranged in
clusters called photosystem
a. embedded in thylakoid membrane
b. 2 kinds of photosystems:
-Photosystem I: wavelength 700nm
-Photosystem II: wavelength 680nm
II. Photosystem II (make ATP)
A. How does it work?
1. sunlight is absorbed by
pigments in the thylakoid
2. photons boost the e- to a higher E
level  EXCITED
3. e- are sent to reaction center..
4. reaction center donates e- to
electron transport chain (ETC)
a. ETC is a series of redox rx
b. stairs analogy
5. The ETC contains a proton pump
a. pumps H+ into the thylakoid …
b. [H+] increases and builds up
pressure
6. ETC donates its electrons to
Photosystem I
a. splitting of 2 H2O molecules:
2 H2O  4 H+ + 4e- + O2
b. H+ are left inside the thylakoid
& O2 diffuses out of plant
7. In the meantime…
a. ATP synthase is used for
ADP ATP
b. chemiosmosis
III. Photosystem I (make NADPH)
A. How does it work?
1. sunlight is absorbed by
pigments in the thylakoid
2. e- from photosystem II are
transferred to reaction center of
Photosystem I…
3. e- are sent to reaction center..
4. reaction center donates e- to
electron transport chain (ETC)
5. e- are transferred to a
reducing protein
a. NADP+  NADPH
IV. Calvin Cycle
A. Carbon Fixation
1. CO2 CHO
2. enzymes incorporate carbon
atoms from CO2 into organic
molecules
3. Light independent reactions
a. does NOT require light directly
but does require ATP & NADPH
b. requires CO2 that enters thru
the stomate
4. There are several ways C is
fixed during PS….
B. Melvin Calvin
1. Background
a. discovered in 1940-50’s at the
Uni of Ca
2. Occurs in all plants and algae…
3. 6 CO2 must enter cycle to
produce a 6-carbon sugar
C. Steps of the Calvin Cycle
1. Carbon Fixation
a. CO2 is attached to RuBP 
resulting in a 6-C molecule
b. C-C-C-C-C-C  C-C-C + C-C-C
PGA
2. Carbon Reduction
a. each molecule of PGA is
reduced to PGAL
PGA  PGAP  PGAL
ATP
NADPH
3. Regeneration of RuBP
a. 1 PGAL may combine to make
C6H12O6
b. most of the PGAL produced is
used to regenerate RuBP
-ATP required
4. The spend ADP & NADP are
returned to the light
dependent rx to become ATP
& NADPH
V. Factors that affect the rate of PS
A. Light Intensity
1. PS increases as intensity
increases until saturation point
is reached
B. CO2 concentration
1. similar to light intensity
C. Temperature
1. PS is a series of enzyme
catalyze rxs and they fail
outside a particular range
Cellular
Respiration
Cellular Respiration Equation
C6H12O6 + 6O2 6CO2 + 6H2O + ATP
- 2ATP
Electron
Transport
Chain
I. Cellular Respiration
A. Steps
1. Glycolysis
a. glucose splits into 2 pyruvate
C6H12O6  2 x pyruvate
b. occurs in cytoplasm
c. +2 ATP…
2. Acetyl coenzyme-A formation
a. pyruvate binds to coenzyme A
b. occurs in the mitochondria
c. -2 ATP…
3. Kreb’s Cycle or Citric Acid Cycle
a. acetyl co-A molecule enters cycle
b. combines with
oxaloacetate  citrates CO2
c. occurs in the matrix
d. +2 ATP…
4. ETC
a. transfers e- from Kreb’s cycle
down a series of protein carriers
b. Energy given off is used to
make ATP
c. terminal e- acceptor is
oxygen H2O
d. occurs in the inner membrane
e. +34 ATP…
B. Exercise Benefits
1. # of mitochondria increase…
a. faster rise in O2 uptake at the
onset of work less O2 debt
2. Cramps & Charlie Horse..
II. Anaerobic Respiration/Fermentation
A. 2 General types of fermentation
1. Alcohol Fermentation
2. Lactic Acid Fermentation
B. Alcohol Fermentation
1. C6H12O6  CO2 + Ethanol + 2 ATP
a. performed by microorganisms;
bacteria and yeast
b. CO2 and bread rising
C. Lactic Acid Fermentation
1. C6H12O6  CO2 + Lactic + 2 ATP
Acid
a. occurs in muscles when body
demands more E than can be
supplied
b. O2 does not have enough time…
2. Initially Lactic acid will be carried
away by the blood….
a. as [LA] increases pH changes
causing the muscles to fatigue
and they will no longer contract
b. Hitting the wall….
Hitting the Wall
3. Lactic acid is transported to the
liver, and converted back to
pyruvate
a. process requires O2, thus why
you breath hard after finishing
race
4. Practical uses of LA fermentation
a. transformation of milk into
cheese, sour cream, and yogurt
-bacteria are inoculated into
the culture and utilize the
sugar to ferment
-Blue cheese: penicillin spores are
mixed with the curds blue
-Swiss Cheese: holes from the
bacteria used produces gas
-Soy Sauce: soy beans and
wheat are fermented by mold
-Pepperoni and Salami
-mixture is stuffed into casings, and
inoculated with lactic
acid producing bacteria
(Lactobacillus plantarum)
-ferments of 24-72 hours…
-Aged Beef
-beef is hung in a
cool place where
bacteria and fungus
grow on the surface
producing acids that
degrade the muscle
tissue and tenderize
the beef
D. Advantages of Fermentation
1. only get 2 ATP, less than 36 ATP
from CR
a. determined by org and activity
level
2. one celled org don’t need much E
3. emergency uses.. Get some E now;
recover later
E. Regulation of CR rate
1. Feedback inhibition
a. Excess ATP shuts off pathway
2. ATP bind to a key enzyme
changes its shape stops ATP
production
3. use ATP  enzyme release the
ATP ATP production begins