Photosynthesis and Respiration

Chapter 6

Photosynthesis The process by which plants convert the

energy of sunlight into the energy of chemical bonds (sugar and starch)

Plants make organic compounds (Carbs) from inorganic compounds (Water and CO2)

The equation Carbon Dioxide + water sugar + Oxygen CO2 + H20 C6H12O6 + O2

Sunlight All organism depend on sunlight for energy

Autotrophs – directly depend on energy to make food

Heterotrophs – indirectly depend on energy because they need to consume autotrophs

Pigments Colored substances that absorb or reflect

light Capture the light energy to be used by the

cell Found in chloroplasts Chlorophyll – appears green

Energy storing compounds When pigments absorb light they boost

electrons to a higher energy level They either are picked up by an electron

carrier NADP+ NADPH Or they are used to make Adenosine

Triphosphate (ATP) from AMP or ADP

Complete the following in your purple book

Pg 117 #1-4 and problem solving

Project topics DNA RNA (protein Synthesis) Mitosis Meiosis Gregor Mendel Karyotypes and Punnett

Suqares Human Genome project Selective breeding

(transgenic plants and animals)

Sex-linked traits Non-disjunction disorders Mutations Hemophilia & Muscular

Dystrophy Kleinfelters and Turner

syndrome Dwarfism & Downs

Syndrome Genetic Engineering Evolution (Darwin)

Photosynthesis – the process Two parts 1) light reaction – Captures light energy and

converts it to stored energy (NADPH or ATP) Requires sunlight

2) Dark reaction – used stored energy to convert CO2 into sugar

Light Reaction Photosynthetic membrane – membrane

within the chloroplast Contains Photosystems –clusters of

pigment molecules (both chlorophyll and accessory pigments)

Photosystem I and Photosystem II

When photosystems are hit with sunlight

electrons are boosted and released These electrons are picked up by NADP+

and ADP These storage molecules will be used to

fuel the dark reaction

Electron transport chain (ETC) In order to be picked up by electron carriers

the molecules must pass down the ETC Electrons released by Chlorophyll will be

replaced by the breakdown of water Oxygen from the breakdown of water is

released as waste

Summary of the light reaction Light hits a photosystem within the

chloroplast and boosts the electron level These electrons are passed down the ETC

and picked up by NADP+ and ADP The electrons are replaced by the

breakdown of water Oxygen is a waste product

???? What is the formula for photosynthesis? What are the reactants? What are the products? What is the main pigment used in

photosynthesis? What replaces the electrons lost in the light

reaction? What two molecules pick up electrons and take

them down the ETC to the dark reaction?

The dark reaction Light does not play a direct part in the

reaction Also known as the Calvin cycle

Five steps of the Calvin Cycle 1st - 3(CO2) combines with a 3(5C)

molecules and form 3 (6C) molecules 2nd – The 6C molecules split and make 6

(3C) molecules 3rd – The molecules rearrange to make 6

(3C) molecules called PGAL NADPH and ATP are used

4th – 1 PGAL is released and 5 PGAL move

on 5th – the 5 (3C) PGAL molecules rearrange

to form 3 (5C) molecules The cycle repeats

Glycolysis and Respiration Break down of sugar Glycolysis – sugar is not completely broken

down Respiration – sugar is completely broken

down C6H12O6 + 6O2 6CO2 + + 6H20

3(CO2)

3(5C) 3(6C)

6(3C)

6 PGAL(3C)

1PGAL (3C)

5 PGAL (3C)

Groups Names Topic Textbook pages 8-10 facts

Questions?????? How does the formula for respiration

compare to the formula for photosynthesis? How do they differ in their use/release of

energy? Write this equation using words. What are the reactants for respiration? What are the products for respiration?

Glycolysis Initial breakdown of glucose molecule 6C sugar is broken down into 2 (3C) PGAL

molecules 2 ATP molecules are needed for this to occur These two PGAL are then converted to pyruvic

acid also a 3C molecule 4 ATP and 2 NADH are produced There is a net gain of 2 ATP and 2 NADH

Respiration If Oxygen is available Respiration will occur In this process the two pyruvic acid

produced during glycolysis are further broken down during the Krebs cycle

This process takes place in the inner membrane of the mitochondria

Steps of the Krebs cycle 1st – Pyruvic acid (3C) is converted to

acetyl-CoA a 2C molecule; 1 CO2 is released

2nd – the acetyl CoA enters the Krebs cycle and joins with a 4C molecule to create a citric acid a 6C molecule

3rd – This 6C molecule is converted to a 5 C molecule by releasing 1 CO2 and NADH

4th - This 5C molecule is converted to a 4C

molecule by releasing 1 CO2 and NADH 5th – This 4C molecule is further

transformed creating 1GTP, 1 NADH and 1FADH2

The cycle begins again

Overview of Respiration 2 Carbon atoms are added in the form of

pyruvic acid 2 Carbon atoms are removed in the from of

CO2 3 NADH, 1FADH2 and 1 GTP molecules

are formed 2 turns yield 6NADH, 2 FADH2 and 2 GTP

ETC Electrons from electron carriers (NADH,

FADH2 and GTP) are passed down an ETC to form ATP

1 GTP – 1 ATP 1 NADH – 3 ATP 1 FADH2 – 2 ATP

ATP yield

Intermediate reaction 2 NADH – 6 ATP

Krebs Cycle 2 GTP – 2 ATP 6 NADH – 18 ATP 2 FADH2 – 4 ATP

Fermentation If cells do not have Oxygen they can not

enter the intermediate step nor the Krebs cycle

They will perform fermentation Fermentation does not require Oxygen and

simply changes pyruvic acid to a more useful

Types of fermentation Lactic acid fermentation

Muscles

Alcoholic fermentation Yeast

Uses the NADH produced in glycolysis Yields 2ATP