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 CO2, H2O, 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 O2 vs. Anaerobic respiration which doesn’t use O2

• 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

O2CO2

BREATHINGLungs

CO2 O2

BloodstreamMuscle cells carrying out

CELLULAR RESPIRATION

Figure 6.1

Sugar + O2 ATP + CO2 + H2O

• Cellular respiration breaks down glucose molecules and stores their energy in ATP (adenosine triphosphate: ADENOSINE –P—P--P)

– The process uses O2 and releases CO2 and H2O

Figure 6.2A

Glucose Oxygen gas Carbon dioxide

Water Energy

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 36 - 38 ATP molecules

The 3 stages of aerobic cellular respiration

KREBSCYCLE

Electron shuttleacrossmembranes

Cytoplasmic fluid

GLYCOLYSIS

Glucose2

Pyruvicacid

2AcetylCoA

KREBSCYCLE

ELECTRONTRANSPORT CHAIN

AND CHEMIOSMOSIS

Mitochondrion

by substrate-levelphosphorylation

used for shuttling electronsfrom NADH made in glycolysis

by substrate-levelphosphorylation

by chemiosmoticphosphorylation

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

https://college.livetext.com/folder/3890451/e3pFLzfM_breadrising.mp4

• In alcoholic fermentation, pyruvic acid is converted to CO2 and ethanol

Figure 6.15A

– This recycles NAD+ to keep glycolysis working

GLYCOLYSIS

2 Pyruvicacid

released

2 EthanolGlucose

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 Pyruvicacid

2 Lactic acidGlucose

Figure 6.15B

XO

Kombucha “Kelp Tea”

• 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 O2 present

Glycolysis

cytoplasm no Glucose (2)Pyruvic acid

2 ATP

Krebs Cycle

(citric acid cycle)

Matrix of mitochondria

no Pyruvic acid is altered into acetylcoA

CO2

NADH

FADH2

2ATP

Electron Transport Chain

Cristae of mitochondria

yes NADH

FADH2

NAD+

FAD++

32 – 34 ATP

Process name

Location in cell

Oxygen used

Reactants

Products

ATP’s made

Anaerobic – Fermentation; used by prokaryotes & eukaryotes if O2 not present

Lactic Acid bacteria; muscle cells

cytoplasm no glucose Lactic acid

2 ATP

Alcoholic yeasts

cytoplasm no glucose Ethanol & CO2

2 ATP

Which stage of aerobic respiration requires ATP?

• Glycolysis• Krebs cycle• Electron transport chain• Fermentation• none of the above

Glycolysis

• http://www.phschool.com/science/biology_place/biocoach/cellresp/intro.html