Photosynthesis

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Transcript Photosynthesis

GOTTA EAT!
PHOTOSYNTHESIS
&
CELL RESPIRATION
PHOTOSYNTHESIS
Photosynthesis
• PLANT CELLS convert light energy to chemical
energy
• Carbon dioxide (CO2) requiring process
• Uses light energy (photons) and water (H2O)
• Producing organic macromolecules (glucose)
SUN
photons
6CO2 + 6H2O  C6H12O6 + 6O2
glucose
6CO2 + 6H2O  C6H12O6 + 6O2
REACTANTS
PRODUCTS
• Carbon dioxide • Glucose
• Water
• Oxygen
• Sunlight energy
Question
Where does photosynthesis
take place?
Plants
And some protists (algae) and bacteria
• Autotrophs: self-producers.
• Location:
1. Leaves
a. stoma
b. mesophyll cells
Mesophyll
Cell
Chloroplast
Stoma
Stomata (stoma)
Pores in a plant’s cuticle through which water
and gases are exchanged between the plant
and the atmosphere.
Oxygen
(O2)
Carbon Dioxide
(CO2)
Guard Cell
Guard Cell
Chloroplast
Organelle where photosynthesis takes place
Stroma
Outer Membrane
Inner Membrane
Thylakoid
Granum
Thylakoid
Thylakoid Membrane
Granum
Thylakoid Space
Question:
Why are plants green?
Chlorophyll Molecules
• Located in the thylakoid membranes of
chloroplasts
• Chlorophyll have Mg+ in the center
• Chlorophyll pigments harvest energy (photons) by
absorbing certain wavelengths
– (blue-420 nm and red-660 nm are most important)
• Plants are green because the green wavelength is
reflected, not absorbed
Wavelength of Light
(nm)
400
500
600
700
Short wave
Long wave
(more energy)
(less energy)
Absorption of
Chlorophyll
Absorption
violet
blue
green yellow
wavelength
orange
red
Question:
During the fall, what
causes the leaves to
change colors?
Fall Colors
• In addition to the chlorophyll pigments,
there are other pigments present.
• During the fall, the green chlorophyll
pigments are greatly reduced revealing
the other pigments.
• Carotenoids are pigments that are either
red or yellow.
Photosynthesis-part 1
Two main parts
(reactions)
1. Light Reaction or
Light Dependent
Reaction
Sun light energy is
used to make energystoring compounds
(ATP and NADPH)
Photosynthesis-part 2
Uses energy (ATP and
2. Sugar making NADPH) from
stages
• Calvin Cycle light rxn to make sugar
(glucose)
or
• Light
Independent
Reaction or
• Dark Reaction
• Carbon
Fixation
1. Light Reaction
(Electron Flow)
• Occurs in the
Thylakoid
membranes
• Electrons flow from
molecule to
molecule giving off
energy as it flows
• This energy can be
harnessed
Chloroplast
Stroma
Outer Membrane
Inner Membrane
Thylakoid
Granum
Thylakoid
Thylakoid Membrane
Granum
Thylakoid Space
Electron Flow
• When light strikes a thylakoid in a
chloroplast, energy is transferred to
electrons in chlorophyll.
• Reaction center- chlorophyll a
• Uses Electron Transport Chain (ETC) as
electrons “jump” to a higher energy level
• Excited electrons generate ATP and
NADPH that temporarily store chemical
energy
ADP + P
ATP
NADP+ + H = NADPH
Electron Flow
• ADP + P
• NADP+ + H


ATP
NADPH
• Oxygen comes from the splitting of
H2O, not CO2
H 2O 
1/2 O2 + 2H+
Calvin Cycle
• Carbon Fixation (light
independent reaction)
• Occurs in the stroma
• Uses ATP and NADPH
from light reaction
• Uses CO2
• To produce glucose: it
takes 6 turns and uses
18 ATP and 12 NADPH
*is a process that occurs
only in autotrophs
(primarily plants)
*requires sunlight, water
and carbon dioxide
*occurs in the chloroplasts
with chlorophyll (green
pigment)
*the process converts solar
energy (sunlight) into
chemical energy (food)
* the food produced is
glucose
(monosaccharide)
CELL RESPIRATION
Cellular Respiration: used by
ALL organisms to get energy
• The products of photosynthesis are the reactants for
respiration.
C6H1206 + O2 = ATP + CO2 +H20
• A chemical reaction that breaks down glucose to get
ATP (cellular energy). Requires enzymes.
• Aerobic respiration-a metabolic process that
requires oxygen
• Anaerobic respiration-a metabolic process that does
not require oxygen
Equation Comparison:
6CO2
+ 6H20 + sun = C6H1206 + 6O2
• Photosynthesis
• Respiration
C6H1206 + 6O2 = ATP+ 6CO2 +6H20
•
•
Cellular Respiration: used by
ALL organisms to get energy
STAGE 1-Glycolysis
(breakdown of
glucose)
STAGE 2a. Kreb’s cycle
b. Electron Transport
Chain
A total of 38 ATP are
formed for every
glucose molecule
Stage 1 - Glycolysis
•
•
Anaerobic process in
the cytoplasm
Glucose is converted
to pyruvate,
producing 2 ATP and
2 NADH (electron
carrier) molecules
4 ATP produced
-2 ATP used
=2 ATP net gain
Stage 2 - Krebs Cycle &
Electron Transport Chain
•
Aerobic respiration
in mitochondria
Pyruvate and
NADH from
Glycolysis are
used to make 36
ATP molecules
Krebs Cycle-
•
•
–
Produces electron
carriers (NADH and
FADH2) and ATP
that temporarily
Did you know?
• Hans Adolph Krebs
– In 1937 Hans Adolph Krebs
discovered the details of the Krebs
cycle. He had to interrupt his work
and leave Nazi Germany prior to
World War 2 because he was
Jewish. In 1953 Krebs was awarded
the Nobel Prize in Physiology or
Medicine for his discovery.
•
1.
2.
Stage 2 - Electron Transport
Chain (ETC)
Electrons donated by
NADH and FADH2 pass
through an electron
transport chain on the
inner membrane of
mitochondria
34 ATP are produced as
H+ ions diffuse into the
inner compartment
through a channel
protein
At the end of the chain,
electrons and H+ ions
combine with oxygen,
forming water.
Fermentation: the recycling
of NAD+
• Anaerobic respiration (no oxygen used)
– the breakdown of glucose (glycolysis)
can continue without oxygen present
• Produces 2 ATP
• Two types:
a. alcoholic fermentation
b. lactic acid fermentation
Alcoholic fermentation
•
1.
2.
•
•
Performed by yeast
(fungus)
Pyruvate is converted to a
two-carbon compound
releasing CO2
Electrons are transferred
from NADH to the twocarbon compound
producing ethanol (ethyl
alcohol)
Reaction produces 2 ATP,
carbon dioxide and
alcohol
Bakers use yeast to make
dough rise; brewers use
yeast to make beverages
carbonated
Lactic acid fermentation
• Used by muscles cells
during rapid exercise when
oxygen is not available.
• Produces 2 ATP and lactic
acid/lactate .
• Allows glycolysis to
continue producing ATP in
muscles as long as the
glucose supply lasts.
• Lactate can build up in
muscle cells causing
muscle soreness.
Cellular Respiration (aerobic
respiration)
*process that occurs in all organisms – PLANTS & ANIMALS
*requires glucose, oxygen
*occurs in the cytoplasm and mitochondria
*the process breaks down chemical energy (glucose) to
release ATP
*the products are carbon dioxide, water, and 38 ATP
*aerobic respiration produces more ATP than anaerobic
respiration
Did you know?
• ATP Molecules
– The human body uses about 1
million molecules of ATP per cell per
second. There are more than 100
trillion cells in the human body.
That’s about 1 x 1020 , or
100,000,000,000,000,000,000 ATP
molecules used in your body each
second!
Comparison of both ……..
CELL
PHOTOSYNTHESIS
RESPIRATION
Make food
Break apart food
Stores energy
Releases energy
Give off O2
Use oxygen
Use sunlight
Use CO2
Give off CO2