DO NOW DO NOW What is the difference between an autotroph and a heterotroph? Why do plants need sunlight? What gases are exchanged between plants and animals?
Jan 01, 2016
DO NOWDO NOWWhat is the difference between
an autotroph and a heterotroph?
Why do plants need sunlight?
What gases are exchanged between plants and animals?
ObjectivesObjectivesTo be able to list the inputs and
outputs of photosynthesis.To be able to identify the
structures in a chloroplast.To be able to summarize light-
dependent reactions.
PhotosynthesisPhotosynthesisLight energy ------> chemical energy
Used by autotrophs to produce food
All of our energy starts as light energy!◦Plants use sunlight to make food
animals eat plants other animals those animals
Photosynthetic OrganismsPhotosynthetic OrganismsGo through Photosynthesis to
produce GLUCOSE…Autotrophs “Producers” in the food webConsist of plants, protists,
cyanobacteria
Phase OverviewPhase Overview1) Light dependent Reactions
◦Light energy is absorbed and converted into chemical energy in the form of ATP and NADPH. (also produces Oxygen!)
2) Light Independent Reactions:(Calvin Cycle)◦CO2 ATP and NADPH are used to make
glucose. *Glucose is the basic building block for more complex sugars such as starch.*
Structures within a Structures within a chloroplastchloroplast
Thylakoids: flattened sac-like membranes arranged
in stacks (stacks are called grana). Light-dependent reactions take place
here. Electron transport occurs in the
thylakoid membrane
Stroma: Fluid filled space outside the grana. Light-independent reactions take place
here.
Light Dependent Light Dependent ReactionsReactions
Step 1: Light energy reaches photosytem II causing the water molecule to split
OHH
H2O
H+
O2+
*H+ is released to the electron transport system.* O2 is given off as a byproduct.
Step 2: Light energy reaches photosystem I and electrons flow from photosystem II to photosystem I. (to replace the electrons lost)
Step 3: Hydrogen ions (protons) are pumped across the membrane as the electrons fall. (think of a hyper child losing energy)
Step 4: Electrons from photosystem I move to a protein called ferrodoxin.
**Ferrodoxin = “helper” protein**
Step 5: Ferrodoxin transfers electrons to NADP+ forming NADPH. (We need this for the next part of photosynthesis!)
Step 6: Hydrogen ions move through the ATP Synthase because of the concentration gradient, creating ATP. (Chemiosmosis) To Calvin Cycle
Light Dependent Light Dependent ReactionsReactions
Lets see it altogether now!
http://www.science.smith.edu/departments/Biology/Bio231/ltrxn.html
Review!Review!What goes into a light dependent
reaction?
What is the goal of a light dependent reaction?
What is given off as a byproduct?
What is the name of the protein needed in a light dependent reaction?
Do NowDo Now
In what part of the chloroplast do light reactions occur?
What are the outputs of light-dependent reactions?
What is the name of the cycle in light-independent reactions?
ObjectivesObjectives
List the inputs and outputs of the Calvin Cycle
Define chemiosmosis and it’s role in photosynthesis.
Summarize light – independent reactions
Perform chromatography to identify the pigments of green leaves.
Calvin CycleCalvin Cycle
Takes place in the stromaUses NADPH and ATP from Phase
I (light dependent reactions)Needs CO2!!!Produces GLUCOSE
Calvin CycleCalvin Cycle
Functions like a sugar factory within a chloroplast
**Regenerates the starting material with each turn
ChemosynthesisChemosynthesis
Mechanism in which ATP is produced as a result from the flow of electrons down a concentration gradient.
Ex: Light reactions (H+ ions and ATP synthase)
Alternative PathwaysAlternative Pathways
Light and Water can limit the amount of photosynthesis a plant can perform.
Some plants develop alternate pathways to maximize energy conservation.
Ex: CAM and C4 plants.
CC44 Plants PlantsThese plants minimize water lostTurn CO2 into a 4 carbon molecule
instead of a 3 carbon moleculeKeeps stomata (plant cell pores)
closed during hot daysEx. Corn and Sugar Cane
CAM PlantsCAM PlantsOccurs in water-conserving
plants that live in deserts, salt marshes, etc.
CO2 only enters leaves at nightTurns CO2 into a “storage
molecule” until needed laterEx. Orchids, cacti, pineapples
Description Calvin C4 CAM
9. The second phase of photosynthesis, in which energy is stored in glucose
10. Pathway(s) that help(s) plants photosynthesize while minimizing water loss
11. Pathway that allows carbon dioxide to enter leaves only at night
12. Light-independent reactions
13. Uses the enzyme rubisco to convert carbon dioxide into molecules that can be used by the cell
14. Type of plant found in hot, dry environments
Do Now – True or FalseDo Now – True or False
1. The anaerobic pathway that follows glycolysis in the absence of oxygen is fermentation.
2. The hydrogen necessary in the electron transport chain comes from the splitting of carbon dioxide molecules.
3. Cellular respiration in eukaryotes is slightly more efficient than in prokaryotes.
4. The Krebs cycle is sometimes called the TCA cycle or the citric acid cycle.
5. Fermentation occurs in the mitochondria.6. Skeletal muscle produces lactic acid when the body
cannot supply enough oxygen.7. Alcohol fermentation is found in some bacteria and in
humans.8. The two pyruvate molecules formed during glycolysis
result in two Krebs cycles.9. Electron transport is the first step in the breakdown of
glucose.