Warm-up

1
Warm-up

• Imagine that you are given 25 germinating pea
  seeds that have been placed in boiling
• water for 5 minutes. You place these seeds in a
  respirometer and collect data. Predict
• the rate of oxygen consumption (i.e., cellular
  respiration) for these seeds, and explain your
  reasons.

2
Monday 10/29 Agenda

• Tutoring starts today!
• Analysis in lab packet
• Share inquiry findings
• Take Lab Quiz
• Homework
• Photosynthesis poster and CH. 10 online
  assignments due tomorrow
• One more week to do test corrections

3
10/30 Agenda

• Chloroplast structure and up to slide 25 (15 min)
• Photosynthesis Light Reaction
• Calvin Cycle
• Homework
• Study poster for open-poster quiz tomorrow
• Print and bring AP Lab 4 Photosynthesis (from my
  website) tomorrow, dont need to read yet

4

• Enduring Understandings
• 1B1 Organisms share many conserved core
  processes and features that evolved and are
  widely distributed among organisms today.
• 2A1 All living systems require constant input
  of free energy.
• 2A2 Organisms capture and store free energy
  for use in biological processes.
• 2B3 Eukaryotic cells maintain internal
  membranes that partition the cell into
  specialized regions (e.g., mitochondria).
• 4A2 The structure and function of subcellular
  components, and their interactions, provide
  essential cellular processes.
• 4A6 Interactions among living systems and with
  their environment result in the movement of
  matter and energy.

5
Standard Deviation and Standard Error for first
part of lab

• Take each groups rates- find mean rate
• Calculate Standard Deviation from mean
• Calculate standard error
• Graph rates on bar graph
• Add standard error bars

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(No Transcript)
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Graph Average Rates with Error Bars
8
Lee, Richard E. Using Microrespirometers to
Measure O2 Consumption by Insects andSmall
Invertebrates. The American Biology Teacher,
vol. 57, no. 5, 28485, 1995..
9
Chloroplasts The Sites of Photosynthesis in
Plants

• Leaves are the major locations of photosynthesis
• Their green color is from chlorophyll, the green
  pigment within chloroplasts
• Chloroplasts are found mainly in cells of the
  mesophyll, the interior tissue of the leaf
• Each mesophyll cell contains 3040 chloroplasts

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• CO2 enters and O2 exits the leaf through
  microscopic pores called stomata
• The chlorophyll is in the membranes of thylakoids
  (connected sacs in the chloroplast) thylakoids
  may be stacked in columns called grana
• Chloroplasts also contain stroma, a dense
  interior fluid

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Figure 10.4
Leaf cross section
Chloroplasts
Vein
Mesophyll
Stomata
CO2
O2
Chloroplast
Mesophyllcell
Outermembrane
Thylakoid
Intermembranespace
20 ?m
Granum
Stroma
Thylakoidspace
Innermembrane
Lets look at model
1 ?m
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Photosynthesis as a Redox Process

• Photosynthesis reverses the direction of electron
  flow compared to respiration
• Photosynthesis is a redox process in which H2O is
  oxidized and CO2 is reduced
• Photosynthesis is an endergonic process the
  energy boost is provided by light

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Figure 10.UN01
becomes reduced
Energy ? 6 CO2 ? 6 H2O
C6 H12 O6 ? 6 O2
becomes oxidized
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The Two Stages of Photosynthesis A Preview

• Photosynthesis consists of the light reactions
  (the photo part) and Calvin cycle (the synthesis
  part)
• The light reactions (in the thylakoids)
• Split H2O
• Release O2
• Reduce NADP to NADPH
• Generate ATP from ADP by photophosphorylation

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• The Calvin cycle (in the stroma) forms sugar from
  CO2, using ATP and NADPH
• The Calvin cycle begins with carbon fixation,
  incorporating CO2 into organic molecules

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Figure 10.6-4
H2O
CO2
Light
NADP?
ADP
P i
CalvinCycle
LightReactions
ATP
NADPH
Chloroplast
CH2O(sugar)
O2
17

• While light travels as a wave, many of its
  properties are those of a discrete particle, the
  photon.
• Photons are not tangible objects, but they do
  have fixed quantities of energy and amount
  depends on wavelength.

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Figure 10.10
RESULTS
Chloro-phyll a
Chlorophyll b
Absorption of light bychloroplast pigments
Carotenoids
400
500
600
700
Wavelength of light (nm)
Rate of photosynthesis (measured by O2 release)
400
500
600
700
(b) Action spectrum
Aerobic bacteria
Filamentof alga
400
500
600
700
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• The action spectrum of photosynthesis was first
  demonstrated in 1883 by Theodor W. Engelmann
• In his experiment, he exposed different segments
  of a filamentous alga to different wavelengths
• Areas receiving wavelengths favorable to
  photosynthesis produced excess O2
• He used the growth of aerobic bacteria clustered
  along the alga as a measure of O2 production

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• Chlorophyll a is the main photosynthetic pigment
• Accessory pigments, such as chlorophyll b,
  broaden the spectrum used for photosynthesis
• Accessory pigments called carotenoids absorb
  excessive light that would damage chlorophyll

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• When a molecule absorbs a photon, one of that
  molecules electrons is elevated to an orbital
  with more potential energy.
• The electron moves from its ground state to an
  excited state.
• The only photons that a molecule can absorb are
  those whose energy matches exactly the energy
  difference between the ground state and excited
  state of this electron.
• Because this energy difference varies among atoms
  and molecules, a particular compound absorbs only
  photons corresponding to specific wavelengths.
• Thus, each pigment has a unique absorption
  spectrum.

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• Excited electrons are unstable.
• Generally, they drop to their ground state in a
  billionth of a second, releasing heat energy.
• Some pigments, including chlorophyll, release a
  photon of light, in a process called
  fluorescence, as well as heat.

Fig. 10.10
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Figure 10.12
Excitedstate
e?
Heat
Energy of electron
Photon(fluorescence)
Photon
Groundstate
Chlorophyllmolecule
(a) Excitation of isolated chlorophyll molecule
(b) Fluorescence
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Fig. 10.9
25
Figure 10.18
STROMA(low H? concentration)
Cytochromecomplex
NADP?reductase
Photosystem I
Photosystem II
Light
4 H
Light
NADP? H?
Fd
Pq
NADPH
Pc
H2O
O2
1/2
THYLAKOID SPACE(high H? concentration)
4 H
2 H
ToCalvinCycle
Thylakoidmembrane
ATPsynthase
ADPP i
ATP
STROMA(low H? concentration)
H
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A Photosystem A Reaction-Center Complex
Associated with Light-Harvesting Complexes

• A photosystem consists of a reaction-center
  complex (a type of protein complex) surrounded by
  light-harvesting complexes
• The light-harvesting complexes (pigment molecules
  bound to proteins) transfer the energy of photons
  to the reaction center

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Figure 10.13
Photosystem
STROMA
Photon
Light-harvestingcomplexes
Reaction-centercomplex
Primaryelectronacceptor
STROMA
Chlorophyll
e?
Thylakoid membrane
Thylakoid membrane
Pigmentmolecules
Special pair ofchlorophyll amolecules
Transferof energy
Proteinsubunits
THYLAKOID SPACE(INTERIOR OF THYLAKOID)
THYLAKOIDSPACE
(b) Structure of photosystem II
(a) How a photosystem harvests light
Each photosystem consists of chlorophylls,
accessory pigments, and proteins. The black
arrows represent photons being passed like a wave
to reaction center chlorophylls that actually
donate their electrons.
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Figure 10.14-5
Linear Electron Flow
Electron transport chain
Primaryacceptor
Primaryacceptor
Electron transport chain
Fd
e?
Pq
e?
e?
e?
NADP?
H2O
Cytochromecomplex
2 H?
H?
NADP?reductase

O2
NADPH
1/2
Pc
e?
P700
e?
P680
Light
Light
ATP
Pigmentmolecules
Photosystem I(PS I)
Photosystem II(PS II)
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Figure 10.15
e?
e?
e?
MillmakesATP
NADPH
e?
e?
e?
Photon
e?
ATP
Photon
Photosystem II
Photosystem I
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Cyclic Electron Flow

• Cyclic electron flow uses only photosystem I and
  produces ATP, but not NADPH
• No oxygen is released
• Cyclic electron flow generates surplus ATP,
  satisfying the higher demand in the Calvin cycle

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Figure 10.16
Primaryacceptor
Primaryacceptor
Fd
Fd
NADP? H?
Pq
NADP?reductase
Cytochromecomplex
NADPH
Pc
Photosystem I
ATP
Photosystem II
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A Comparison of Chemiosmosis in Chloroplasts and
Mitochondria

• Chloroplasts and mitochondria generate ATP by
  chemiosmosis, but use different sources of energy
• Mitochondria transfer chemical energy from food
  to ATP chloroplasts transform light energy into
  the chemical energy of ATP
• Spatial organization of chemiosmosis differs
  between chloroplasts and mitochondria but also
  shows similarities

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• In mitochondria, protons are pumped to the
  intermembrane space and drive ATP synthesis as
  they diffuse back into the mitochondrial matrix
• In chloroplasts, protons are pumped into the
  thylakoid space and drive ATP synthesis as they
  diffuse back into the stroma

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Figure 10.17
Chloroplast
Mitochondrion
CHLOROPLASTSTRUCTURE
MITOCHONDRIONSTRUCTURE
H?
Diffusion
Thylakoidspace
Intermembranespace
Electrontransportchain
Thylakoidmembrane
Innermembrane
ATPsynthase
Matrix
Stroma
ADP ? P i
ATP
H?
Key
Higher H?
Lower H?
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• ATP and NADPH are produced on the side facing the
  stroma, where the Calvin cycle takes place
• In summary, light reactions generate ATP and
  increase the potential energy of electrons by
  moving them from H2O to NADPH

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Lets watch animation of Phase I

• http//www.mhhe.com/biosci/genbio/biolink/j_explor
  ations/ch09expl.htm

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Concept 10.3 The Calvin cycle uses the chemical
energy of ATP and NADPH to reduce CO2 to sugar

• Carbon enters the cycle as CO2 and leaves as a
  sugar named glyceraldehyde 3-phospate (G3P)
• For net synthesis of 1 G3P, the cycle must take
  place three times, fixing 3 molecules of CO2
• The Calvin cycle has three phases
• Carbon fixation (catalyzed by rubisco)
• Reduction
• Regeneration of the CO2 acceptor (RuBP)

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• Carbon enters the cycle as CO2 and leaves as a
  sugar named glyceraldehyde 3-phospate (G3P)
• For net synthesis of 1 G3P, the cycle must take
  place three times, fixing 3 molecules of CO2
• The Calvin cycle has three phases
• Carbon fixation (catalyzed by rubisco)
• Reduction
• Regeneration of the CO2 acceptor (RuBP)

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Figure 10.19-3
Input
(Entering oneat a time)
3
CO2
Phase 1 Carbon fixation
Rubisco
3
P
P
Short-livedintermediate
P
6
3
P
P
3-Phosphoglycerate
Ribulose bisphosphate(RuBP)
6
ATP
6 ADP
3 ADP
CalvinCycle
6
P
P
3
ATP
1,3-Bisphosphoglycerate
6 NADPH
Phase 3Regeneration ofthe CO2 acceptor(RuBP)
6 NADP?
6 P i
P
5
G3P
6
P
Glyceraldehyde 3-phosphate(G3P)
Phase 2 Reduction
For every one net G3P, requires 9 ATP and 6 NADPH
from the light reaction.
1
P
G3P(a sugar)
Glucose andother organiccompounds
Output
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Photosynthesis is the biospheres metabolic
foundation

• In photosynthesis, the energy that enters the
  chloroplasts as sunlight becomes stored as
  chemical energy in organic compounds.

• - About 50 of the organic material made is
  consumed as fuel for cellular respiration in
  plant mitochondria.
• Rest is stored or used to build other organic
  compounds.

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• On a global scale, photosynthesis is the most
  important process to the welfare of life on
  Earth.
• Each year photosynthesis synthesizes 160 billion
  metric tons of carbohydrate per year.

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10/31 Agenda

• Finish photosynthesis
• Review posters while I check them
• Photosynthesis quiz (20 minutes) open poster
• Statistical analysis - standard deviation and
  standard error (standard error bars on graph) (20
  min)
• I check lab packet from yesterday while you work
  in groups
• Intro Lab 4 and assign cuvettes
• http//www.phschool.com/science/biology_place/labb
  ench/lab4/intro.html
• Homework
• Prelab worksheet for Lab 4, skip part A, be ready
  to do part B tomorrow Read Lab, part B only
• Unit Test next Tuesday 11/6 covers chapters 6-10
  BE STUDYING!!!!

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11/1 Agenda

• Intro and Set up 4B (25 min)
• Slides on spectrophotometer
• Set up blanks together. Calibrate spec and
  review how to use.
• Assign jobs recorder, timekeeper, cuvette
  mixer, spec operator (all help setup)
• Assign cuvettes each group does one of the four
  plus an inquiry tube
• Inquiry choices screens, colored light, acid,
  base, salt, ice etc.
• Run Lab 4B (20 min)
• I check prelabs during this
• make use of your wait time by setting up graph
• Clean up and share data (10 min)
• Dump contents of cuvettes down the drains, then
  use test tube brush to clean out. Dry with paper
  towel. Wipe sides down with Kimwipes and put
  back in flask in bucket.
• Homework
• Do 4B Analysis all of Analysis should be done
  for me to check tomorrow, including graph
• Unit Test next Tuesday 11/6 covers chapters 6-10
• you should be putting in at least a half hour of
  study/review per night!!!

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• When light meets matter, it may be reflected,
  transmitted, or absorbed.
• Different pigments absorb photons of different
  wavelengths.
• A leaf looks green because chlorophyll, the
  dominant pigment, absorbs red and blue light,
  while transmitting and reflecting green light.

Fig. 10.6
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SPECTROPHOTOMETER TECHNIQUE
Chlorophyllsolution
Photoelectrictube
Refractingprism
Whitelight
Galvanometer
605 nm is wavelength absorbed by DPIP
High transmittance(low absorption)Chlorophyll
absorbsvery little green light.
Greenlight
Slit moves topass lightof selectedwavelength.
Low transmittance(high absorption)Chlorophyll
absorbsmost blue light.
Bluelight
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Each year

• Make 3 copies of the next slide put in separate
  powerpoint, have kids record data and email to
  them

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Clean up and share data with your side of the
room (5 min)Dump contents of cuvettes down the
drains, then use test tube brush to clean out.
Dry with paper towel. Wipe sides down with
Kimwipes and put back in flask in bucket.
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11/2 Agenda

• Hand back quizzes
• Quick review prelab
• Analysis and post lab discussion I check while
  you present (also last lab packet)
• Lab bench quiz for Lab 4
• Homework
• Do conclusion only (use rubric) for
  Photosynthesis lab in your notebook due Monday
• Unit Test next Tuesday 11/6 covers chapters 6-10
• Free response questions due Monday