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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
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