CHAPTER 8 Cellular Energy

8-2 Photosynthesis

thylakoid granum stroma pigment NADP + Calvin cycle Cellular Energy Vocabulary Section 2

Journal  Create a picture that shows the process of photosynthesis (what goes in, what comes out, etc…)  Start with this

JOURNAL  In your own words, define “photosynthesis”

TIME MACHINE  Cells are not “born” with a supply of ATP. So, where does the energy to make ATP come from? From the ____________ we eat. Organisms that obtain energy by consuming other living things are _____________________. Other organisms can produce food using energy from sunlight. These organisms are called _______________. food heterotrophs autotrophs

Photosynthesis Overview  In the process of photosynthesis, plants convert the energy of sunlight into chemical energy stored in the bonds of carbohydrates (food).

Photosynthesis Overview

Journal  Write the written and chemical equations for photosynthesis.

Photosynthesis occurs in pigmented structures called chloroplasts.

Photosynthesis occurs in two phases: Light-Dependent Reactions Light-Independent Reactions

Phase One: Light-Dependent Reactions  Location: Thylakoid  Light energy is absorbed by the chloroplasts and converted into chemical energy in the form of ATP and NADPH.

Electron Transport & Chemiosmosis (See Page 225 in textbook) Light energy absorbed by photosystem II is used to split a molecule of water. When water splits, oxygen is released from the cell, H + ions (protons) stay in the thylakoid space and an activated (excited) electron enters the ETC As electrons move through the membrane protons are pumped into the thylakoid space. The electron- acceptor molecule transfers the electrons along a series of electron- carriers to photosystem I. At Photosystem I, electrons are energized and NADPH is formed. Chemiosmos is: Protons accumulate in the thylakoid space, creating a concentratio n gradient. When protons move across the thylakoid membran e through ATP synthase, ADP is converted to ATP

Cellular Energy Phase Two: The Calvin Cycle (Light Independent Reactions)  Location: Stroma  In the second phase of photosynthesis, called the Calvin cycle, energy is stored in organic molecules such as glucose.

Cellular Energy

Rubisco  Enzyme  Converts inorganic carbon dioxide molecules into organic molecules that can be used by the cell

Photosynthesis Summary 

PHOTOSYNTHESISLIGHT- DEPENDENT REACTIONS CALVIN CYCLE LOCATION WHAT GOES IN? WHAT COMES OUT?

Alternative Pathways  C 4 plants  CAM plants Occur in environments in which the amount of water or carbon dioxide is insufficient. Plants have structural modifications that allow sufficient carbon dioxide uptake, while simultaneously minimizing water loss.

Quick lab, page 234