Cellular Metabolism Photosynthesis and Cellular Respiration Chapters 8

Cellular Metabolism: Photosynthesis and Cellular Respiration Chapters 8 -9

l What is the ultimate purpose of nutrition? To obtain energy l We use this energy for: to fuel life processes Getting ATP out of glucose is called______ and it occurs in the ____ of Eukaryotes.

l How do organisms get nutrition? l Autotrophs or producers obtain glucose by producing it. Photosynthesis converts light energy into food energy. Examples of organisms: Cyanobacteria (bluegreen algae), plants, protists, l Heterotrophs or consumers obtain food/glucose by consumer other organisms. Examples- Animals

Venus Flytraps – missing some important amino acids so they get it from insects.

l The chemical reaction for Photosynthesis is: sunlight Water + Carbon Dioxide + -----> Glucose + Oxygen sunlight 6 H 2 O + 6 CO 2 -----> C 6 H 12 O 6+ 6 O 2 l The chemical reaction for Cellular Respiration is: Glucose + Oxygen ------ Carbon Dioxide + Water Energy C 6 H 12 O 6 + 6 O 2 ------- 6 CO 2 + 6 H 2 O 36 ATP

l ATP-Adenosine Triphosphate. ATP the most important energy-containing compound in biological systems. l The energy from ATP can be used for : l mechanical functions ______________________________ l active transport ______________________________ l chemical reactions necessary for life ______________________________

l More than 10 million new ATP molecules are produced per second in cells. Muscle and nerve cells produce even more! l An ATP molecule releases energy whenever …… l ……. last phosphate bond is broken

Cellular Respiration: The Use of Food Energy to make ATP l The process by which chemical energy stored in food is used to form ATP to fuel life processes. l The balanced equation for cellular respiration: C 6 H 12 O 6 + 6 O 2 ------ 6 CO 2 + 6 H 2 O 36 ATP l What types of organisms conduct cellular respiration? ALL living organisms ALL OF THE TIME.

1 st – we will discuss photosynthesis (producers only) 2 nd – we will discuss cellular respiration (ALL organisms – producers, consumers, decomposers)

Chloroplast Organelle where photosynthesis takes place. Stroma Outer Membrane Inner Membrane Thylakoid stacks are connected together Thylakoid Granum 18

Photosynthesis - 2 stages 1. Light Dependent Reactions 2. Light Independent Reactions (used to be called dark reactions) The two chemical reactions of photosynthesis are localized: 1. light-dependent reactions- occurs on the thylakoid membranes of the chloroplast 2. light-independent reactions - occurs in the surrounding stroma

Two Groups of Reactions 1. Light-dependent reactions ¡ Chlorophyll and other molecules of the thylakoids trap sunlight energy ¡ Sunlight energy is converted to the energy carrier molecules ATP and NADPH ¡ Water molecule is split and Oxygen gas is released as a by-product

Two Groups of Reactions 2. Light-independent reactions ¡ Enzymes in the stroma synthesize glucose and other organic molecules using the chemical energy stored in ATP and NADPH ¡ Inorganic CO 2 gets converted to glucose C 6 H 12 O 6 Organic

Pigments: l The color of an object is the color of the light that it ___________. l There are different types of pigments that can be used in photosynthesis: l The most important is Chlorophyll -blue/green in color -it absorbs mainly red and blue wavelengths of light l Others include: l Carotene-orange color l Xanthophyll-yellow color l These pigments are seen in the fall when the main pigments are moved to the roots of the plant

The Big Picture of Photosynthesis l Light “Dependent” Reactions ¡ Light sends electrons in the thylakoid to a high energy state ¡ Water is split to replace electrons and oxygen is formed l Light “Independent” Reactions ¡ ATP used to convert 6 carbon dioxide molecules into glucose

Balanced Equation for Photosynthesis l l l sunlight 6 H 2 O + 6 CO 2 -----> C 6 H 12 O 6+ 6 O 2 How many molecules of CO 2 are used to make one glucose molecule? ____ How many molecules of H 2 O must be split to make one molecule of glucose? ____ How many molecules of oxygen (O 2) are formed in the equation? _____ Like cellular respiration, photosynthesis is a series of chemical reactions called a series of reactions that together are called a biochemical pathway

WHAT DO PLANTS USE GLUCOSE FOR? l l l 1) Cellular Respiration 2) stored as starch 3) forms cell wall (cellulose)

WHAT DO ANIMALS USE GLUCOSE FOR? l 1)_Cellular respiration l 2) stored as glycogen l 3)energy is used to build other compounds like proteins, lipids and nucleic acids.

Cellular Respiration is also more complex than one simple reaction. It occurs in 3 stages. 1. glycolysis 2. kreb cycle 3. electron transport chain …assuming there is oxygen for aerobic cellular respiration.

l Cellular respiration is not one single reaction. Instead it is a series of reactions that together are called a biochemical pathway. l All types of organic compounds including carbohydrates, lipids and proteins can be used at points along the biochemical pathway in order to form ATP.

1. Glycolysis Glucose (6 C) C-C-C-C 2 ATP 2 ADP + P 2 ATP - used 4 ATP - produced NET – 2 ATP produced C-C-C copyright cmassengale C-C-C 29

2. Krebs Cycle (Citric Acid Cycle) (actually an intermediate step before this (3 C 2 C) 1 Acetyl Co. A (2 C) OAA (4 C) Citrate (6 C) Krebs Cycle FADH 2 (one turn) 2 CO 2 3 NAD+ FAD 3 NADH ATP copyright cmassengale ADP + P 30

3. ETC - Electron Transport Chain and Oxidative Phosphorylation (Chemiosmosis for NADH) higher H+ concentration Intermembrane Space 1 H+ 2 H+ E NADH + H+ 3 H+ T C 2 H+ + 1/2 NAD+ H+ Inner Mitochondrial Membrane O 2 H O 2 (Proton Pumping) Matrix ATP Synthase ADP + P H+ ATP lower H+ concentration copyright cmassengale 31

Overview of Glucose Breakdown l If oxygen is absent fermentation occurs ¡pyruvate is converted into either lactate, or into ethanol and CO 2 l If oxygen is present cellular respiration occurs

Overview of Glucose Breakdown l The main stages of glucose metabolism are: ¡ Glycolysis ¡ Cellular respiration (if oxygen is present then the products of glycolysis go to the mitochondria and kreb cycle and electron transport chain (ETC) occurs producing a lot of ATP – most of the ATP is made during the ETC ) ¡If no oxygen is present then anaerobic respiration takes place - fementation

Anaereobic Respiration or Fermentation: Production of ATP in the absence of Oxygen

Two Types of Cellular Respiration l Respiration using oxygen: Aerobic Cellular Respiration ¡ Found in : most plants and animals l Respiration without oxygen: Anaerobic cellular respiration ¡ Found in : unicellular organisms (bacteria yeast) possible in plants and animals-human muscles too

Alcohol fermentation l glycolysis produces 2 ATPs and fermentation produces alcohol and carbon dioxide l Glycolysis is the first step: l chemical equation: Heat C 6 H 12 O 6 ---- 2 C 3 H 4 O 3 ---- Ethanol + CO 2 l Certain bacteria and yeasts undergo alcohol fermentation when oxygen is in short supply. We use yeast and alcohol fermentation to brew beer.

Alcoholic Fermentation produces alcohol and CO 2

l Energy difference between the two types of respiration about 34 ATPs! l Aerobic Cellular Respiration = 36 ATPs!!! l Anaerobic Cellular Respiration =2 ATPs!!! l Which is more effictive? _______

Stages in Aerobic Cellular Respiration: l A. Glycolysis: l Glycolysis means to split glucose: glyco - (glucose) + –lysis (to split). l Glycolysis takes place in the cytoplasm l During glycolysis: glucose is split into 2 molecules of pyruvic acid. l Pyruvic acid is 3 -carbon molecule. l The equation for glycolysis: C 6 H 12 O 6 2 C 3 H 4 O 3

l B. Aerobic Cellular Respiration to Form ATP : l Aerobic Cellular Respiration takes place in the _mitochondria l During Aerobic Cellular Respiration: pyruvic acid molecules are split further to form a total of 34 ATP per glucose molecule.

The Big Picture of Aerobic Cellular Respiration 1) Reactions in Glycolysis occur in the cytoplasm 2) Additional Reactions needed to form ATP: l Krebs Cycle – 2 ATPs l Electron Transport Chain – 32 ATPs!!! 3) These additional reactions occur in: mitochondria

Efficiency of aerobic cellular respiration: l 60% of energy from food is converted into ATP l Think back to cellular transport: l If a cell has to use active transport to bring a molecule of glucose into the cell for cellular respiration, is it worth it for the amount of energy the cell gets from the molecule of glucose? l Yes, 1 ATP molecule used to bring 1 molecule of glucose into the cell l 1 molecule of glucose can produce about 36 ATP

Plant that beer is made from

Lactic acid fermentation l glycolysis produces 2 ATPs and lactic acid l Glycolysis is the first step l chemical equation: Heat C 6 H 12 O 6 --- 2 C 3 H 4 O 3 --- Lactic Acid l Lactic acid fermentation occurs in bacteria, fungi and even human muscles.

Feel the Burn! No Pain No GAIN!! l What causes the “muscle burn” after extreme workouts? l Not enough oxygen gets to your muscles as you are working out, so ATP is produced via lactic acid fermentation. l The Lactic Acid build up in your muscles causes the burning sensation.