Photosynthesis

All organisms use energy to carry out the functions of life.

Agenda

Go over Vocabulary Definitions Photosynthesis Web Activity Notes: Photosynthesis-light & pigments Worksheet: Absorption of Chlorophyll

What are the reactants and products of photosynthesis?

What are the colors of the visible light spectrum?

In what cellular organelle does photosynthesis take place?

Why is photosynthesis important?How is the process of photosynthesis in C4, C3, and CAM plants different?

Importance of Photosynthesis Transforms sunlight energy into chemical energy

stored in molecules (bonds) Bond energy within triose phosphate formed in

photosynthesis is transferred between organisms within the food pyramid (more energy at bottom than top) Triose phosphate (glyceraldehyde 3-phosphate) is

converted to carbohydrates, lipids, amino acids

Photosynthesis releases oxygen to atmosphere

Reactants Sunlight Water Carbon dioxide

ProductsTriose phosphate (Glucose)

Oxygen

H2O + CO2 + light energy (C6H12O6)+ O2

Capturing the Light “Light dependent reactions” take place in

chloroplast

found in mesophyll

of leaf. Grana within

thylakoid membrane Stroma-solution

Surrounding grana

Light and Pigments Sun light appears white, but it is actually

composed of a variety of colors called the Visible Spectrum.

Light can be reflected, absorbed or transmitted by an object.

Pigment absorb light, therefore the light reflected or transmitted no longer appears white

Peaks indicateLight absorbed

Trough where light is reflected

The color you see is what is reflected.

Ex. Chlorophyll (a,b) absorbs blue and red light, but reflects green light

Review

Complete the Absorption of Chlorophyll Worksheet

What are the reactants and products of photosynthesis?What are the colors of the visible light spectrum?In what cellular organelle does photosynthesis take place? Why is photosynthesis important?

Agenda

Review Light Absorption Review Vocabulary Notes: Structure of Leaf & pigment Complete Pigments & Light Absorption PSSA Worksheet

How does the structure of a chloroplast lead to light absorption?

What are the variety of pigments found in the thylakoid of a chloroplast?

Structure of Leaf Leaves are a plant's main photosynthetic

organs. Gases and water vapor come in and out of

a leaf through its stoma.

Epidermis Outer layer which produces a waxy waterproof

coating. undersurface produces guard cells, which swell and

shrink to close and open the pores (stomata) which control the loss of water vapor (transpiration) and the entry of carbon dioxide.

Mesophyll contain the photosynthetic cells of the leaf.

long columnar cells nearer the surface (palisade parenchyma)

looser irregular cells beneath (the spongy mesophyll parenchyma).

Log onto:

Select: #4 Structure of a Leaf#6 Chloroplast Structure

http://www.phschool.com/science/biology_place/biocoach/photosynth/intro.html

Chloroplast Pigments Within the thylakoid

are a variety of pigments. Chlorophyll a-

yellow/green Chlorophyll b-

blue/green Carotenoids - orange

Each pigment absorbs a different wavelength of light.

Chlorophyll a is directly involved in the light reactions of photosynthesis

Chlorophyll b and carotenoids are considered to be accessory pigments, assisting Chlorophyll a in capturing light energy.

Review

Complete Pigments & Light Absorption PSSA Worksheet

How does the structure of a chloroplast lead to light absorption?What are the variety of pigments found in the thylakoid of a chloroplast?

Agenda

Vocabulary Quiz Notes: Photolysis & light Reaction Complete Section 6-1 Review Worksheet

& Photosynthesis PSSA Worksheet

What occurs during photolysis?

How does the structure of a photosystem lead to it function?

What is the main purpose of the light dependent phase of photosynthesis?

Photolysis

Splitting of water molecules Oxygen is released through stomata H+ picked up by NADP and pumped through

thylakoid to stroma for Calvin cycle Carbon Dioxide is absorbed through

stomata and used in the Calvin cycle

Light Dependent Phase-thylakoid Groups of chlorophyll and carotenoid

pigment molecules are found in the thylakoid membrane Photosystem I Photosystem II

Accessory pigment molecules in both photosystems absorb light energy causing electrons to become excited.

Energy is passed within the photosystem through pigment molecules to chlorophyll a

Electron Transport Chain

Aided by enzymes, therefore affected by temperature Excited electrons leave chlorophyll a molecules to a

primary electron acceptor in the stroma of the chloroplast

Electron acceptor donates electrons to a series of molecules located in the thylakoid

allowing protons(H+) to move into the thylakoid

Electron Transport Chain cont.

Photosystem I electrons are replaced by electrons from Photosystem II Photosystem II gets the electrons from

splitting water, for every 2 water split, 4 electrons are available

If this did not happen, photosynthesis would stop

Chemiosmosis/ATP Synthase Relies on a concentration gradient of

protons across the thylakoid membrane. Protons are pushed through ATP Synthase

in the thylaloid membrane Adds a phosphate group to ADP making

ATP

Review

Complete Section 6-1 Review Worksheet Complete Photosynthesis & Light

Absorption PSSA Worksheet

What occurs during photolysis?How does the structure of a photosystem lead to it function?What is the main purpose of the light dependent phase of photosynthesis?

Agenda

Review Lab: Plant Stoma Notes: Light Independent Phase &

Alternative Pathways Complete Biochemistry of Photosynthesis

PSSA Worksheet

What is the main purpose of the light independent phase of photosynthesis?

How is the process of photosynthesis in C4, C3, and CAM plants different?

Light Independent Phase Also called the Calvin Cycle Produces organic compounds, using the energy stored in ATP

and NADPH in the light reactions and carbon dioxide Steps

CO2 diffuses into stroma combining with an enzyme (RuBP), the molecule is split and becomes 3-PGA

Each PGA is converted to another molecule(3-phosphate) in a 2 part step One receives a P from ATP, and the other receives a

Proton (H+) from NADPH One G3P leaves to make carbohydrates One is converted back to RuBP to be used again

Summary

Carried out by Plants C3 plants.

because the CO2 is first incorporated into a 3-carbon compound. Stomata are open during the day. Photosynthesis takes place throughout the leaf. Most plants are C3.

C4 plants. because the CO2 is first incorporated into a 4-carbon compound. Stomata are partially open during hottest part of the day. into the plant very quickly, and then it "delivers" the CO2 directly to

RUBISCO for photosynthesis. Photosynthesis takes place in inner cells Ex. Corn, Sugar Cane, Crab grass

CAM plants. CAM stands for Crassulacean Acid Metabolism because the CO2 is stored in the form of an acid before use in

photosynthesis. Stomata open at night (when evaporation rates are usually lower) and are

usually closed during the day. CAM plants include many succulents such as cactus, agaves, bromeliads and also some orchids

Review What is the main purpose of the calvin

cycle of photosynthesis?

•Complete Biochemistry of Photosynthesis PSSA Worksheet