Cellular Respiration and the Mitochondrion ……

Nearly all the cells in our body break down sugars for ATP production CELLULAR RESPIRATION Introduction

Most cells of most organisms harvest energy aerobically using oxygen – The aerobic harvesting of energy from sugar is called cellular respiration – Cellular respiration yields CO 2, H 2 O, and a large amount of ATP What can you see in this picture?

Which types of organisms use cellular respiration and fermentation for energy production– autotrophs or heterotrophs? Heterotrophs. Autotrophs use photosynthesis.

Aerobic respiration requires O 2 vs. Anaerobic respiration which doesn’t use O 2 Some cells only use anaerobic respiration Some cells use aerobic respiration Some cells usually use aerobic but may resort to anaerobic respiration if necessary Differences in how cells break down glucose - aerobic vs. anaerobic respiration

Structure of the Mitochondrion The process of cellular respiration takes place in the mitochondria of eukaryote cells

Breathing and cellular respiration are closely related. Breathing supplies oxygen to our cells for cellular respiration and removes carbon dioxide from our cells which is a waste product of cellular respiration O2O2 CO 2 BREATHING Lungs CO 2 O2O2 Bloodstream Muscle cells carrying out CELLULAR RESPIRATION Figure 6.1 Sugar + O 2  ATP + CO 2 + H 2 O

Cellular respiration breaks down glucose molecules and stores their energy in ATP (adenosine triphosphate: ADENOSINE –P—P--P) – The process uses O 2 and releases CO 2 and H 2 O Figure 6.2A GlucoseOxygen gasCarbon dioxide WaterEnergy Chemical equation for cellular respiration

Where is most of the ATP produced in eukaryotic cells? the mitochondria

Cellular respiration oxidizes sugar and produces ATP in three main stages – Glycolysis occurs in the cytoplasm – The Krebs cycle and – The electron transport chain occur in the mitochondria Respiration occurs in three main stages STAGES OF CELLULAR RESPIRATION AND FERMENTATION

For each glucose molecule that enters cellular respiration, chemiosmosis produces ATP molecules The 3 stages of aerobic cellular respiration KREBS CYCLE Electron shuttle across membranes Cytoplasmic fluid GLYCOLYSIS Glucose 2 Pyruvic acid 2 Acetyl CoA KREBS CYCLE ELECTRON TRANSPORT CHAIN AND CHEMIOSMOSIS Mitochondrion by substrate-level phosphorylation used for shuttling electrons from NADH made in glycolysis by substrate-level phosphorylation by chemiosmotic phosphorylation Maximum per glucose: Figure 6.14

How many ATP molecules can be produced from one glucose molecule? 36 to 38

Most ATP produced in aerobic respiration occurs in the process of: Glycolysis The Krebs cycle Chemiosmosis Substrate-level phosphorylation Correct answer: Chemiosmosis

Polysaccharides can be broken down to monosaccharides and then converted to glucose for glycolysis Proteins can be digested to amino acids, which are chemically altered and then used in the Krebs cycle Fats are broken up and fed into glycolysis and the Krebs cycle Animal Cells use many kinds of organic molecules as fuel for cellular respiration

Under anaerobic conditions, many kinds of cells can use glycolysis alone to produce small amounts of ATP – But a cell must have a way of replenishing NAD+ Fermentation is an anaerobic alternative to aerobic respiration XO

In alcoholic fermentation, pyruvic acid is converted to CO 2 and ethanol Figure 6.15A –This recycles NAD + to keep glycolysis working GLYCOLYSIS 2 Pyruvic acid released 2 Ethanol Glucose Figure 6.15C XO

In lactic acid fermentation, pyruvic acid is converted to lactic acid –As in alcoholic fermentation, NAD + is recycled Lactic acid fermentation is used to make cheese and yogurt GLYCOLYSIS 2 Pyruvic acid 2 Lactic acid Glucose Figure 6.15B XO

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In addition to energy, cells need raw materials for growth and repair – Some are obtained directly from food – Others are made from intermediates in glycolysis and the Krebs cycle Biosynthesis (making cell parts and organic compounds) uses ATP Food molecules provide raw materials for biosynthesis

All organisms have the ability to harvest energy from organic molecules – Plants, but not animals, can also make these molecules from inorganic sources by the process of photosynthesis The fuel for respiration ultimately comes from photosynthesis Figure 6.18

Aerobic – Needing oxygen; process used in eukaryote cells when O 2 present Glycolysis cytoplasmnoGlucose(2)Pyruvic acid 2 ATP Krebs Cycle (citric acid cycle) Matrix of mitochondria no Pyruvic acid is altered into acetylcoA CO 2 NADH FADH 2 2ATP Electron Transport Chain Cristae of mitochondria yesNADH FADH 2 NAD+ FAD++ 32 – 34 ATP Process name Location in cell Oxygen used ReactantsProductsATP’s made Anaerobic – Fermentation; used by prokaryotes & eukaryotes if O 2 not present Lactic Acid bacteria; muscle cells cytoplasmnoglucoseLactic acid 2 ATP Alcoholic yeasts cytoplasmnoglucoseEthanol & CO 2 2 ATP

Which stage of aerobic respiration requires ATP? Glycolysis Krebs cycle Electron transport chain Fermentation none of the above Glycolysis

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