PHOTOSYNTHESIS & CELLULAR RESPIRATION

PHOTOSYNTHESIS

The process of converting light energy to chemical energy and storing it in the bonds of sugar.

Sunlight + CO2 Glucose Light Reaction Dark Reaction Takes place in the chloroplast, the parts of a

chloroplast include the outer and inner membranes, intermembrane space, stroma, and thylakoids stacked in grana. The chlorophyll is built into the membranes of the thylakoids.

LIGHT REACTION The light reaction happens in the thylakoid

membrane and converts light energy to chemical energy.

This chemical reaction must, therefore, take place in the light. Chlorophyll and several other pigments such as beta-carotene are organized in clusters in the thylakoid membrane and are involved in the light reaction.

Each of these differently-colored pigments can absorb a slightly different color of light and pass its energy to the central chlorphyll molecule to do photosynthesis.

The central part of the chemical structure of a chlorophyll molecule is a porphyrin ring, which consists of several fused rings of carbon and nitrogen with a magnesium ion in the center.

DARK REACTION

The dark reaction takes place in the stroma within the chloroplast, and converts CO2 to sugar.

This reaction doesn't directly need light in order to occur, but it does need the products of the light reaction (ATP and another chemical called NADPH).

The dark reaction involves a cycle called the Calvin cycle in which CO2 and energy from ATP are used to form sugar.

The first product of photosynthesis is a three-carbon compound called glyceraldehyde 3-phosphate. Almost immediately, two of these join to form a glucose molecule.

CELLULAR RESPIRATION

Cellular respiration allows organisms to use (release) energy stored in the chemical bonds of glucose (C6H12O6). The energy in glucose is used to produce ATP. Cells use ATP to supply their energy needs. Cellular respiration is therefore a process in which the energy in glucose is transferred to ATP.

In respiration, glucose is oxidized and thus releases energy. Oxygen is reduced to form water.

The carbon atoms of the sugar molecule are released as carbon dioxide (CO2).

GLYCOLOSIS

The complete breakdown of glucose to carbon dioxide and water requires two major steps: 1) glycolysis and 2) aerobic respiration. 

Glycolysis produces two ATP. Thirty-four more ATP are produced by aerobic pathways if oxygen is present.

FERMENTATION

In the absence of oxygen, fermentation reactions produce alcohol or lactic acid but no additional ATP.

AEROBIC RESPIRATION

Aerobic respiration occurs when oxygen is available.

pyruvate ? CO2 + H2O It occurs in the mitochondrion. NAD+ and FAD carry electrons to the electron

transport system. In the electron transport system, NADH and

FADH2 are used to produce ATP as electrons are passed from one carrier to another. Eventually the electrons combine with hydrogen ions and oxygen (reduction) to form water.

MICROSCOPES

Types of Microscopes The light microscope. The common light

microscope used in the laboratory is called a compound microscope because it contains two types of lenses that function to magnify an object. The lens closest to the eye is called the ocular, while the lens closest to the object is called the objective. Most microscopes have on their base an apparatus called a condenser, which condenses light rays to a strong beam. A diaphragm located on the condenser controls the amount of light coming through it. Both coarse and fine adjustments are found on the light microscope 

OTHER TYPES

Dark-field microscope Phase-contrast microscope Fluorescent microscope Electron microscope

OVERVIEW

Now that today’s lesson has concluded, gather into groups in order to complete the lab.

Make sure to clean your station before you leave.

DO NOT forget clickers for tomorrow’s unit quiz.

UNIT QUIZ

QUESTION 1: WHERE DOES PHOTOSYNTHESIS TAKE PLACE?

A) EpidermisB) MesophyllC) Guard CellsD) Chloroplast

QUESTION 2: WHICH REACTION PHASE DOES THE KREBS CYCLE TAKE PLACE IN?

A) Light ReactionB) Dark ReactionC) Both ReactionsD) The Krebs cycle is involved with Cellular

Respiration.

QUESTION 3: IN THE ABSENCE OF OXYGEN WHAT CYCLE DOES CELLULAR RESPIRATION PERFORM?

A) GlycolosisB) PyruvateC) Acytel CoAD) FermentationE) Cellular Respiration cannot occur without

oxygen.

QUESTION 4: WHAT IS THE TOTAL YIELD OF ATP?

A) 32-24B) 36-38C) 39-41D) 42-44

QUESTION 5: WHICH TYPE OF MICROSCOPE WAS USED IN THE LAB?

A) Light MicroscopeB) Fluorescent MicroscopeC) Electron MicroscopeD) Ocular Microscope

CONGRATULATIONS

You’ve made it through one of the hardest units of 10th grade Biology! If you have any further questions regarding this unit you may ask me after class, come to my office hours, or check out our classroom wiki space Resources page.