Photosynthesis and Cellular Respiration Outline 1I. Photosynthesis A. Introduction B. Reactions II. Cellular Respiration A. Introduction B. Reactions

Photosynthesis Method of converting sun energy into chemical energy usable by cells Word Equation: Carbon dioxide + water + sunlight  glucose + oxygen Chemical Equation: 6CO 2 + 6H 2 O + Energy  C 6 H 12 O 6 + 6O 2

Photosynthesis takes place on The thylakoid membrane in a specialized structures inside plant cells called chloroplasts – Light absorbing pigment molecules e.g. chlorophyll

Chlorophyll absorbs red and blue light from the sunlight that falls on leaves. Therefore, the light reflected by the leaves is diminished in red and blue and appears green to our eyes.

How do we explain for these colors? In the fall, lower temperature and lack of sun light slows down the production on chlorophyll pigment Other pigments in leaves including the carotenoids become dominant. They reflect orange and red color; thus, making leaves appear so

Photosynthesis involves 2 reactions: 1.Light dependent reaction 2.Light independent reaction (Calvin cycle)

1. Light dependent reaction: occurs in the thylakoid membrane inside the chloroplast 1a. Light energy is absorbed by the chlorophyll 1b. Electrons jump out of the chlorophyll atoms 1c. Electrons move down the electron transport chain (series of proteins that pass the electrons along). Electrons are caught by the NADPH compound. ATP is made. 1d. Photolysis: Water is broken down into oxygen (given off by plant) and electrons (replace lost electrons in chlorophyll). These electrons recharge the system so the light reaction can happen again.

2. Dark reaction- Calvin cycle: occurs in the stroma of chloroplast 2a. Electrons and ATP from light reaction get dumped into the Calvin Cycle to run it 2b. Calvin Cycle: Series of steps that build up compounds using carbon dioxide from the air 2c. PGAL compound sometimes leaves the cycle. 2 PGAL compounds added together make 1 glucose.

- Photosynthesis transforms sunlight energy into chemical energy stored in the bonds of glucose molecules

Cellular Respiration Overview A process occurs in the mitochondria where chemical energy stored in food is converted into ATP Occurs in both Plants and Animals Overall Reaction Word Equation: glucose + oxygen  Carbon dioxide + water + energy Chemical Equation: C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + Energy

Cellular Respiration Aerobic cellular respiration Anaerobic cellular respiration (aka fermentation) requires NO oxygen and carried out by yeast, some bacteria, and sometimes animals requires oxygen and carried out by plants, animals, and some bacteria Steps of aerobic respiration 1. Glycolysis: First step breaks down glucose into pyruvate (Intermediate step: Change pyruvate to acetyl CoA) 2. Citric Acid Cycle: Second step uses the acetyl CoA to make electrons for the last step 3. Electron transport chain: Third step uses the electrons to make a lot of ATP Also called fermentation 2 types: alcoholic fermentation and lactic acid fermentation - Both begin with glycolysis - No citric acid cycle or electron transport chain

Glycolysis (does not require O 2)

How many ATP made? Glucose

How many ATP made?

32

ATP tally for aerobic respiration: Glycolysis : 2 ATP Citric Acid Cycle : 2 ATP Electron Transport Chain : 32 ATP 1 Glucose generates 36 ATP in all for aerobic respiration Summarizing CR: rrespiration.html

Alcoholic fermentation: Pyruvate  ethyl alcohol + carbon dioxide Lactic acid fermentation Pyruvate  lactic acid Carried out by yeast and some bacteria Used in brewing beer, making wine, and baking bread and cakes Carried out by your muscles when you’re exercising hard (need ATP) and can’t get oxygen into you fast enough (can’t do aerobic respiration) Causes muscle cramps and soreness Anaerobic Cellular Respiration (or Fermentation)

FERMENTATION

Compare PS and CR They’re complimentary processes. Why? Because reactants of one are the products of the other The simple story between PS and CR:

CO 2, water Glucose (C 6 H 12 O 6 ),O 2 Glucose (C 6 H 12 O 6 ) yes no yes

Hands-on clothespin lab Lactic acid fermentation Trial#of Squeezes Dominant hand Trial#of Squeezes Non-dominant hand