cellular respiration ……. nearly all the cells in our body break down sugars to provide the...
TRANSCRIPT
Cellular Respiration……
• Nearly all the cells in our body break down sugars to provide the energy to make ATP
• Most cells of most organisms obtain energy aerobically using oxygen– The aerobic processing of energy from sugar is called
cellular respiration– Cellular respiration yields CO2, H2O, and a large
amount of ATP
CELLULAR RESPIRATION
Introduction
• 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
In Our Body:• 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
• 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
Important Molecules Involved
NAD+
FAD++Electron and hydrogen ion carrier molecules
NAD+ carries 2 electrons and one hydrogen ion/ molecule
FAD++ carries 4 electrons and two hydrogen ions/ molecule
Glycolysis – In cytoplasm6 carbon sugar (1 molecule)
3 carbon molecule ( 2 molecules)
ATP needed to break molecule apart
NAD+ collects electrons and hydrogen and forms ATP
Kreb Cycle – matrix of mitochondrion
A multi-step process involving many enzymes that uses oxygen to break down the pyruvic acid molecules to CO2, captures energy as ATP, and collects energized electrons and hydrogen to send to cristae membranes of mitochondrion
ELT & Chemiosmosis – cristae of mitochondrion
Chemiosmosis involves the pumping of protons through special channels in the membranes of mitochondria from the inner to the outer compartment. The pumping establishes a proton gradient that flows through ATP synthase to make 32-34 ATP
• 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
• 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 (no oxygen), many kinds of cells can use glycolysis alone to produce small amounts of ATP – But a cell must have a way of replenishing or
regenerating NAD+ (NADH NAD+)
Fermentation is an anaerobic alternative to aerobic respiration
• In alcoholic fermentation, pyruvic acid (pyruvate) 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
Alcoholic Fermentation
• In lactic acid fermentation, pyruvic acid (pyruvate) is converted to lactic acid (lactate)– 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
Lactic Acid Fermentation
• 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