CHAPTER 10 PHOTOSYNTHESIS

Chemoautotrophs-oxidize inorganic chemicals in their environment to produce energy for metabolism

brown algae

euglena

cyanophyta—blue-green algae

Van Niel determined that purple sulfur bacteria get their H’s from H2S which lead to the hypothesis that green plants took their H’s from H2O

A photon’s energy is inversely proportional to its wavelength

Why aren’t these longer wavelengths used?

What is the problem with these shorter wavelengths?

Thylakoid Membrane

H+

H+

H+H+H+H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

Primary acceptor noncyclic

Cytochrome

Path of H+

PS 680

PS II

PS 700

PS I

e-

e-

e-

e-

e-

e-

Path of cyclic electrons

Path of Noncyclic electrons

e-

e-

Primary acceptor cyclic

Proton

motive force

2 photons of light

Primary acceptor noncyclicProton pump

e-

e-

H20

O

OH-

H2O

H-O-H OH-

Water ionized by proton pump

2 Photons of light

H+

H+

H-O-H

H-O-H

OH-

OH-

NADP+

NADPH2

cytochrome

ADPⓟ

ATP

3-Phosphoglycerate

1,3-Biphosphoglycerate

G3P

RuBP

Each round uses 3 ATP and 2 NADPH2 and only adds

1 CH2O

Ru-P

Rubisco

http://science.nhmccd.edu/biol/ap1int.htm

PEP carboxylaseis in high conc. in the mesophyll cells

There is no RuBP carboxylasein the mesophyll cells but the light reactions and the fixation of CO2 occur there.

Bundle-sheath cells have chloroplasts that contain few thylakoids and no photosystems and thus do not carry on the light reactions and never produce O2

Since rubisco is sequestered here it can never oxidize rather than carboxylate RuBP.

PEP has a much higher affinity for CO2 than rubisco and no affinity for O2. Thus CO2 concentrations are lower.

mesophyllarea

Leaf of a C4 Plant Cuticle

Upper Epidermis

Spongy mesophyll

lower epidermis

palisademesophyll

guard cells

stomata

PEP carboxylase’s higher affinity for CO2 results in lower concentrations of CO2 in the mesophyll and thus when the stomata open, there is a faster exchange.

These compounds are all acids.

These compoundsare all acidic

CHAPTER 10 TEST37 Multiple Choice 6 Fill In the Blanks w/19 blanks 1 Essay