bellringer-april 22, 2015 fill in the letters. overview of cellular respiration h. biology ms. kim
TRANSCRIPT
Bellringer-April 22, 2015
FILL IN THE LETTERS
Overview of Cellular Respiration
H. BiologyMs. Kim
Energy Flows into ecosystems as sunlight and leaves as heat
Light energy
ECOSYSTEM
CO2 + H2O
Photosynthesisin chloroplasts
Cellular respirationin mitochondria
Organicmolecules + O2
ATP
powers most cellular work
Heatenergy http://wps.aw.com/bc_campbell_biology_7/
Carbon Cycle
Reminder….Anabolic pathways (“A” for add together)
Build molecules from simpler ones (ex: photosynthesis)
Consume energy (endergonic or endothermic)Catabolic pathways (“C” for cut in parts)
Break down complex molecules into simpler compounds (ex: cell respiration)
Release energy (exergonic or exothermic)
Cellular respiration
Most efficient catabolic pathwayConsumes O2 and organic
molecules (ex: glucose)Yields ATP To keep working cells
must regenerate ATP
Catabolic pathways yield energy by oxidizing organic fuels
The breakdown of organic molecules is exergonic (exothermic)
One catabolic process, fermentationIs a partial degradation of sugars that occurs
without oxygen
Another example is cellular respiration
Cellular respiration
Occurs in mitochondria similar to combustion of gas in an engine after
O2 is mixed with hydrocarbon fuel.Food and O2 = fuel for respiration. The exhaust =CO2 and H2O.
The overall process is:organic compounds + O2 CO2 + H2O + energy
(ATP + heat)
Carbohydrates, fats, and proteins can all be used as the fuel, but most useful is glucose.
Mitochondria
Intermembrane Space
• Powerhouse of the cell!• The organelle responsible for cellular respiration
• The Krebs Cycle and ETC take place here ATP is produced here!
• It is a double membrane with the inner membrane highly folded (to increase the surface area and make the mitochondria more efficient).
Mitochondrion Structure
Mitochondrion Structure• Outer membrane – similar to plasma
membrane; contains integral proteins• Inner membrane- NOT permeable to ions
(needs help to cross); there is a membrane potential across the inner membrane; contains ATP synthase
• Cristae – large surface area due to folding• Matrix - gel-like in middle or lumen; many
contains enzymes for cellular respiration
RECALL…Redox ReactionsCatabolic pathways yield energy
Due to the transfer of electronsRedox reactions
Transfer e-’s from one reactant to another by oxidation and reductionIn oxidation
Substance loses e-s (it’s oxidized)In reduction
Substance receives e-s (it’s reduced)
Examples of redox reactions
Na + Cl Na+ + Cl–
becomes oxidized(loses electron)
becomes reduced(gains electron)
Xe- + Y X + Ye-
**energy must be added to remove e-X = e- donor = reducing agent and reduces Y.
Y = e- recipient = oxidizing agent and oxidizes X.
Oxidation of Organic Fuel Molecules During Cellular Respiration
• During cellular respiration– Glucose is oxidized – oxygen is reduced– E-’s lose potential energy energy is released
C6H12O6 + 6O2 6CO2 + 6H2O + Energy
becomes oxidized
becomes reduced
http://student.ccbcmd.edu/~gkaiser/biotutorials/cellresp/ets_flash.html
Electrons are not transferred directly to oxygen but are passed first to a coenzyme called NAD+ or FAD
NAD+
HO
OO O–
OO O–
O
O
O
P
P
CH2
CH2
HO OHH
HHO OH
HO
H
H
N+
C NH2
HN
H
NH2
N
N
Nicotinamide(oxidized form)
NH2+ 2[H](from food)
Dehydrogenase
Reduction of NAD+
Oxidation of NADH
2 e– + 2 H+
2 e– + H+
NADH
OH H
N
C +
Nicotinamide(reduced form)
N
Figure 9.4
NAD+ and FAD= e- acceptor and oxidating agent
2 H 1/2 O2
(from food via NADH)
2 H+ + 2 e–
2 H+
2 e–
H2O
1/2 O2
Controlled release of energy
for synthesis of
ATP ATP
ATP
ATP
Electron transport chain
Free
ene
rgy,
G
(b) Cellular respiration
+
Electron Flow =food NADH/FADH2 ETC oxygen
Cellular Respiration – Background info• Equation – C6H12O6 + 6O2 → 6CO2 + 6 H2O + 36 or 38 ATP
-When food is broken down, energy is released gradually and stored in ATP.
-Respiration is done by BOTH plants and animals
The Stages of Cellular Respiration
• Respiration is a cumulative process of 3 metabolic stages
1. Glycolysis2. Kreb’s Cycle (The citric acid cycle)
3. Electron Transport Chain (Oxidative phosphorylation)
The 3 Stages Glycolysis
Breaks down glucose into 2 molecules of pyruvateMakes NADHMakes a little bit of ATP
Kreb’s Cycle (Citric acid cycle)Completes the breakdown of glucoseMakes NADH and FADH2
CO2 is waste productMakes a little bit of ATP
Electron Transport Chain (Oxidative phosphorylation)Driven by the electron transport chainGenerates ALOTTTTT of ATPO2 is the final electron acceptor and gets reduced to make
WATER
General overview – Cellular Respiration1.Glycolysis:• In the cytosol• Anaerobic• Turns glucose to 2 pyruvate net gain of 2 ATP and 2 NADH
2. Krebs:• In the mitochondrial matrix • Makes little ATP, NADH, and FADH2 (electron taxis) • Passes e- to ETC
3. ETC → uses chemiosmosis to make LOTS of ATP
Exit Slip-April 22, 2015• Draw a cycle of the ecosystem between
photosynthesis and cellular respiration. • Include the following: photosynthesis, carbon
dioxide, light energy, heat energy, oxygen, glucose, water, and ATP.