Photosynthesis – Part ISpring 2013 - Althoff Reference: Mader & Windelspecht Ch. 7)

Lec07

• Photosynthetic Organisms

• Process of Photosynthesis

Definitions

• Photosynthesis converts ____________ into the ________________ of a ________________

• ____________ = photosynthetic organisms that produce their _______________examples: ________________

________________________________

• Autotrophs = _______________

Cyanobacteria

Algae

Plants

_________________

The opposite of AUTOTROPHS are…

• _______________ = ____________ …they cannot make their own food…aka ____________________ carbohydrates.

• Heterotrophs, as do autotrophs, use ___________________ produced by photosynthesis as a source of building blocks for growth and repair…as well as a source of chemical energy for __________ work.

Birds, Fish,Mammals, etc.

Fungi

Insects

Mussels

_________________

Photosynthesis by product….

• Carry on ________________________

Value to all organisms

= ___

O2bubbles

from Elodea leaves

Besides the O2 “byproduct” of photosynthesis…there are other benefits to

humans:

• Building materials (think lumber)

• Fabrics (think cotton)

• Paper

• Pharmaceuticals

• Aesthetic value (think flowers)

Photosynthesis takes place in the “green” portions of plants (aka leaves)

• For flowering plants (most of what is on earth), ____________ tissue is present that specializes in photosynthesis.

mesophyll

Entry of raw materials for photosynthesis….

• CO2 in air enters through ________

• H2O in soil enters through _______, then up ________ ______ (aka vein)

• CO2 and H2O, once in the leaf, ________ into _______________

mes

op

hyl

l

Top of leaf

Chloroplast

Actual chloroplast ~37,000 x

Chloroplast structure

• ___________ ___________:

outer and inner

• __________ semi-fluid interior

• __________ – flattened sacs

• _______ (gramum pl.)– stacked thylakoids

doub

le m

embr

ane

Grana close up….

thylakoidspace

thylakoidmembrane

independentthylakoid

in a granum

overlappingthylakoid

in a granum

Thylakoids

• Spacing of thylakoids thought to be connected to the ____________________ thylakoids within a chloroplast….

• The result is a _________________ …providing a tremendous amount of surface area for photosynthesis to occur.

Thylakoids and Stroma

• The __________________ actually contains the chlorophyll…and other pigments capable of absorbing solar energy.

• The ________ contains an energy-rich solution where CO2 is first attached to an organic compound…then reduced to a carbohydrate.

Photosynthesis: The Process

• The equation implies that photosynthesis involves ________ (=oxidation-reduction)…and the movement of electrons from one molecule to another

• This means a) CO2 gains an electron and b) H20 loses one….a ____ is “transferred”

Photosynthesis: The Process

• In photosynthesis, solar energy is used to generate the ___________________ the CO2 to a __________________.

• Keep in mind, this carbohydrate represents the _______ produced by land plants, algae, and cyanobacteria that feeds _____ the biosphere.

Two Important Coenzymes

• ________ is the coenzyme of oxidation-reduction active during photosynthesis. When reduced it accepts 2 electrons and and 1 hydrogen atom to become _______

• When NADPH oxidizes, it give up its electrons

• NADP+ + 2e- + H+ NADPH

Back to the Elodea leaf…

• What molecule supplies the electrons that reduce NADP+ during photosynthesis?

The _____________ _________________ that is split!

Two Sets of Reactions

• _________________—so named because they only occur when solar energy is available. Associated with “_______” energy

• __________________________—named for Melvin Calvin who discovered the enzymatic reaction that reduces CO2. Associated with “____________” energy

LIGHT REACTIONSCALVIN CYCLE

REACTIONS

O2 CH2O

Light Reactions

• Sunlight/solar energy __________ by chlorophyll that drives photosynthesis

• Solar energy “________” the electrons that move down an _________ _______________. As it does, energy released is captured as _____ molecules.

Mader Fig. 6.12 p114

Light Reactions

To summarize….

•Solar energy _________________(ATP, NADPH)

•But, O2 is given off, too

O2

Calvin Cycle

• Enzymes present speed up the reduction of CO2 during __________________

• Occurs in the ____________________ of the chloroplast stroma

• When reduction results in carbohydrate…it can later be converted to glucose…this is achieved by using ATP and NADPH _____ the light reactions

Calvin Cycle Reactions

To summarize….

•_________ energy __________ energy(ATP, NADPH) (carbohydrate)

CH2O