Prof. Dr. Samih Tamimi Bio 304101 Photosynthesis Biology 304101.

Slides:



Advertisements
Similar presentations
Oxidation and reduction – always take place together
Advertisements

An Overview of Photosynthesis Most of the energy used by almost all living cells ultimately comes from the sun  plants, algae, and some bacteria capture.
Autotrophs Organisms capture and store free energy for use in biological processes.
Ch. 10 Diagrams Photosynthesis. (a) Plants (b)Multicellular alga (c)Unicellular protists (d) Cyanobacteria (e)Purple sulfur bacteria 10  m 1  m 40 
Photosynthesis using light to make food
Photosynthesis. 1. An Overview of Photosynthesis & Respiration 2. Autotrophs and producers 3. Electromagnetic Spectrum & light energy 4. Chloroplasts:
PHOTOSYNTHESIS. YOU MUST KNOW… HOW PHOTOSYSTEMS CONVERT SOLAR ENERGY TO CHEMICAL ENERGY HOW LINEAR ELECTRON FLOW IN THE LIGHT REACTIONS RESULTS IN THE.
Overview: The Process That Feeds the Biosphere
Ch 10 Photosynthesis--> To make with light!. LE 10-2 Plants Unicellular protist Multicellular algae Cyanobacteria Purple sulfur bacteria 10 µm 1.5 µm.
Photosynthesis 6 CO H Light  C 6 H 12 O O H 2 O Occurs in 2 Stages – both take place in the Chloroplasts Light Reactions Splitting.
Review Chapter 8 PHOTOTSYNTHESIS. autotrophs The first stage of photosynthesis, the light harvestings steps are called……
Photosynthesis in Detail
LIGHT & DARK REACTIONS OF PHOTOSYNTHESIS.
PHOTOSYNTHESIS
1 Photosynthesis. 2 All cells can break down organic molecules and use the energy that is released to make ATP. Some cells can manufacture organic molecules.
PHOTOSYNTHESIS Chapter 10. PHOTOSYNTHESIS Overview: The Process That Feeds the Biosphere Photosynthesis Is the process that converts light (sun) energy.
Overview of Photosynthesis
Chp Photosynthesis. LE 10-2 Plants Unicellular protist Multicellular algaeCyanobacteria Purple sulfur bacteria 10 µm 1.5 µm 40 µm.
PHOTOSYNTHESIS How plants use the sun’s energy to make sugar Occurs in the chloroplasts of plant cells I.The process is broken into 3 sets of reactions.
Chapter 10 Photosynthesis.
Photosynthesis. Getting Energy Autotrophs- make their own energy (usually from the sun) Ex. plants Heterotrophs- get energy from other organisms Ex. animals,
Overview: The Process That Feeds the Biosphere Photosynthesis is the process that converts solar energy into chemical energy Directly or indirectly, photosynthesis.
Photosynthesis: Capturing Energy Chapter 8. Light Composed of photons – packets of energy Visible light is a small part of the electromagnetic spectrum.
Chapter 3 - Photosynthesis: The Details
Photosynthesis: Life from Light
Photosynthesis Dr.Samih Tamimi
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece.
Photosynthesis – Process by which some organisms capture light energy and store it in organic compounds (mainly carbohydrates, sugars) Autotrophs – make.
Photosynthesis Overview Energy for all life on Earth ultimately comes from photosynthesis 6CO H 2 O C 6 H 12 O 6 + 6H 2 O + 6O 2 Oxygenic photosynthesis.
C 3 Photosynthesis Chapter 10. What you need to know! How photosystems convert solar energy to chemical energy. How linear electron flow in the light.
Journal Explain the relationship between photosynthesis and cellular respiration. Define autotroph and heterotroph.
The overall equation for the cellular respiration of glucose is A) C 5 H 12 O O 2 → 5 CO H 2 O + energy. B) 5 CO2 + 6 H 2 O → C 5 H 12 O 6.
Pathways that Harvest and Store Chemical Energy 6.
Photosynthesis: The Light Reactions & The Calvin Cycle.
Photosynthesis Ch. 7.
8 Photosynthesis.
Figure
PHOTOSYNTHESIS Photosynthesis requires 2 steps.
AP Biology What do you see in this picture?
PHOTOSYNTHESIS watch?v=tSHmwIZ9FNw.
The light reactions convert solar energy to the chemical energy of ATP and NADPH ● Chloroplasts are solar-powered chemical factories ● The conversion.
Photosynthesis Overview video 3 mins Overview video 3 mins.
The Light-Independent Reactions (Dark Reactions) Chapter Pgs BUT FIRST! A review of yesterday’s Light-Dependent Reactions: Photosystems.
Chapter 10: Photosynthesis Photosynthesis transforms solar light energy into chemical bond energy stored as sugar.
Photosynthesis: The Details. Photosynthesis Divided into two steps: 1.The Light Reactions Noncyclic electron flow 2.The Calvin Cycle Cyclic electron flow.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Excitation of Chlorophyll by Light When a pigment absorbs light, it goes from.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Photosynthesis.
Photosynthesis Chapter 10 Part 2. The Light Reactions Driven by visible light – light is electromagnetic radiation – only small fraction of radiation.
Photosynthesis Ch. 7.
Energy in Living Systems
Photosynthesis.
Photosynthesis Chapter 6.
Overview: The Process That Feeds the Biosphere
Photosynthesis Details!
Photosynthesis Chapter 10.
Photosynthesis.
AP Bio Photosynthesis Review
Photosystems & Light Reactions AP Biology Ms. Day
Photosynthesis: Life from Light and Air
Photosynthesis.
Chapter 10 Photosynthesis
Photosynthesis: Life from Light and Air
Experiments! For example:
Photosynthesis Chapter 10.
Photosynthesis overview
Quiz over cellular respiration
Chapter 10 Photosynthesis.
Chapter 6 Photosynthesis.
Photosynthesis Divided into two steps: The Light Reactions
Lecture 3 Outline (Ch. 8) Photosynthesis overview
Presentation transcript:

Prof. Dr. Samih Tamimi Bio Photosynthesis Biology

Prof. Dr. Samih Tamimi Bio The Two Stages of Photosynthesis: A Preview Photosynthesis consists of two processes The Light reactions NEEDS LIGHT Light Dependent Reactions The Calvin cycle A.k.a- Dark Reactions or Light Independent Reactions DOES NOT NEED LIGHT

Prof. Dr. Samih Tamimi Bio The Light Reactions  Occur in the grana (& thylakoids)  Convert solar energy to chemical energy  Chlorophyll absorbs solar energy  Split water  release oxygen gas (a by-product)  produce ATP (using chemiosmosis)  Forms NADPH from NADP+ (an e- acceptor)  Temporarily stores high energy e-’s  “Electron shuttle bus”

Prof. Dr. Samih Tamimi Bio The Calvin Cycle  Occurs in the stroma  Forms SUGAR from carbon dioxide  Carbon fixation occurs (CO 2  fixed carbon)  using ATP for energy and NADPH for reducing power (adding e-s to fixed carbon)  Fixed carbon  carbohydrate

Prof. Dr. Samih Tamimi Bio  An overview of photosynthesis H2OH2O CO 2 Light LIGHT REACTIONS CALVIN CYCLE Chloroplast [CH 2 O] (sugar) NADPH NADP  ADP + P O2O2 ATP G3P

Prof. Dr. Samih Tamimi Bio Light Reactions (in detail)  The light reactions convert solar energy to the chemical energy of ATP and NADPH

Prof. Dr. Samih Tamimi Bio RECALL: Color we SEE = color most reflected by pigment; other colors (wavelengths) are absorbed  BLACK  all colors are reflected Light Reflected Light Chloroplast Absorbed light Granum Transmitted light

Prof. Dr. Samih Tamimi Bio Spectrophotometer  Machine that sends light through pigments  measures fraction of light transmitted and absorbed at each wavelength  Produces an absorption spectrum

Prof. Dr. Samih Tamimi Bio  An absorption spectrum  graph plotting light absorption versus wavelength White light Refracting prism Chlorophyll solution Photoelectric tube Galvanometer Slit moves to pass light of selected wavelength Green light The high transmittance (low absorption) reading indicates that chlorophyll absorbs very little green light. The low transmittance (high absorption) reading chlorophyll absorbs most blue light. Blue light

Prof. Dr. Samih Tamimi Bio  The absorption spectra of three types of pigments in chloroplasts

Prof. Dr. Samih Tamimi Bio  The action spectrum of a pigment  Profiles the relative effectiveness of different wavelengths of radiation in driving photosynthesis Rate of photosynthesis (measured by O 2 release) Action spectrum. This graph plots the rate of photosynthesis versus wavelength. The resulting action spectrum resembles the absorption spectrum for chlorophyll a but does not match exactly (see part a). This is partly due to the absorption of light by accessory pigments such as chlorophyll b & carotenoids.

Prof. Dr. Samih Tamimi Bio  Chlorophyll a  The main photosynthetic pigment (primary pigment)  Accessory Pigments  Absorb different wavelengths of light  pass energy to chlorophyll a

Prof. Dr. Samih Tamimi Bio Excitation of Chlorophyll by Light  When a pigment absorbs light  It goes from a ground state (stable) to an excited state (unstable)

Prof. Dr. Samih Tamimi Bio Photosystems  Reaction centers used in Light Reactions  Made of light harvesting proteins (complexes)  Funnel (move) energy of photons (light pieces) to the middle of reaction center  INSIDE thylakoid membrane  2 DIFFERENT CENTERS  Photosystem II  Photosystem I

Prof. Dr. Samih Tamimi Bio Primary election acceptor Photon Thylakoid Light-harvesting complexes Reaction center Photosystem STROMA Thylakoid membrane Transfer of energy Special chlorophyll a molecules Pigment molecules THYLAKOID SPACE (INTERIOR OF THYLAKOID) e–e– When a reaction-center “special” chlorophyll a molecule absorbs energy An electron gets bumped up to a primary electron acceptor edu/~cmallery/255/2 55phts/photosynthesi s.swf edu/~cmallery/255/2 55phts/photosynthesi s.swf

Prof. Dr. Samih Tamimi Bio Different Photosystems  BOTH found in thylakoid membrane  2 types  photosystems II (PII)  Uses chlorophyll a called P680  1 ST photosystem in membrane  photosystems I (PI)  Uses chlorophyll a called P700  2 ND photosystem in membrane

Prof. Dr. Samih Tamimi Bio types of e- flow 1. Non-cyclic photophosphorylation 1. Cyclic photophosphorylation

Prof. Dr. Samih Tamimi Bio Noncyclic Electron Flow Steps 1. PII  excited e- to primary e- acceptor 2. Photolysis- water splits by enzyme  e-s are replaced from lost chl a P680 H 2 0  2 H+ + 2e- + ½ O 2 (2 O’s combine and O 2 is released) 3. Electron Transport Chain  proteins in thylakoid membrane pass e-s (become reduced)  Flow of e-’s is exergonic  releases energy to make ATP  Proteins used = Cytochromes, PC, and PQ complexes

Prof. Dr. Samih Tamimi Bio Chemiosomosis – the process that forms ATP during light reactions  Protons (H+) are pumped ACTIVELY into thylakoid space (lumen) from stroma durin electron transport  Protons (H+) from split water build up in thylakoid space (lumen)  MORE acidic  H+’s then DIFFUSE down ATP synthase channels in stroma

Prof. Dr. Samih Tamimi Bio  Non cyclic light reactions & Chemiosmosis

Prof. Dr. Samih Tamimi Bio Cyclic Electron Flow  Under certain conditions  Photoexcited electrons take an alternative path (shorter pathway)  Why use this pathway?  Sugar production (Calvin Cycle) uses a lot more ATP than NADPH  Sometimes, autotrophs run low on ATP  needs to replenish ATP levels and uses cycle e- flow

Prof. Dr. Samih Tamimi Bio Why is it “cyclic”?  This process is cyclic since electrons return to the reaction center.  An electron donor (i.e.- water) is NOT required and oxygen is NOT produced.

Prof. Dr. Samih Tamimi Bio Cyclic Electron Flow Steps 1. Photon hits PS1 2. E-s enter PSI P700  a primary e- acceptor 3. E-s travel BACK to P700 through FD cytochrome complex and PC ATP is produced using ATP synthase and H+ diffusion…NO NADPH!!!

Prof. Dr. Samih Tamimi Bio  In cyclic electron flow  Only photosystem I is used  Only ATP is produced NO NADPH

Prof. Dr. Samih Tamimi Bio NON CYCLIC CYCLIC

Prof. Dr. Samih Tamimi Bio The Calvin cycle uses ATP and NADPH to convert CO 2 to sugar  The Calvin cycle  Occurs in the stroma

Prof. Dr. Samih Tamimi Bio Recall…

Prof. Dr. Samih Tamimi Bio ?H?H A L G E + F C D M B I + J K

Prof. Dr. Samih Tamimi Bio ?H?H A L G E + F C D M B I + J K

Prof. Dr. Samih Tamimi Bio The Calvin cycle has three phases 1. Carbon fixation 2. Reduction 3. Regeneration of the CO 2 acceptor (RuBP)

Prof. Dr. Samih Tamimi Bio The Calvin Cycle Steps CARBON FIXATION 1. CO2 enters cycle and attached to a 5- carbon sugar called ribulose bisphosphate (RuBP) forming 6-C molecule (unstable)  Enzyme RUBISCO catalyzes reaction 2. Unstable 6-C molecule immediately breaks down to two 3-C molecules called 3-phosphoglycerate (3-PGA)

Prof. Dr. Samih Tamimi Bio REDUCTION 3. Each 3-phosphoglycerate (3-PGA) gets an additional phosphate from ATP (from LIGHT RXN)  becomes 1,3 bis phosphoglycerate 4. NADPH reduces 1,3 bisphosphoglycerate to Glyceraldehyde-3-phosphate (G3P) G3P = a sugar that stores potential energy Every 3 CO 2  yields 6 G3P’s BUT only 1 can be counted in net gain for carbohydrate

Prof. Dr. Samih Tamimi Bio REGENERATION OF CO2 ACCEPTOR (RuBP) 5. The C- skeletons of 5 G3P molecules are rearranged into 3 RuBP molecules ATP is used !!!!

Prof. Dr. Samih Tamimi Bio The Calvin cycle Phase 1: Carbon fixation Phase 2: Reduction Phase 3: Regeneration of the CO 2 acceptor (RuBP) output NOTE: MORE ATP is needed than NADPH!!

Prof. Dr. Samih Tamimi Bio Calvin Cycle Overview  For 1 G3P molecule made  9 ATP molecules are used  6 NADPH molecules are used  G3P (starting material to make other organic molecules (glucose, starch, etc.)