cp bio chapter 9 cellular respiration
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CP BIO Chapter 9 Cellular Respiration. How Cells Harvest Chemical Energy. All life activities need energy. CP BIO: Ch. 9 Cell Respiration. a. Maintain homeostasis ; do life functions breathe, circulate blood active transport, synthesize molecules regulate temperature, etc. - PowerPoint PPT PresentationTRANSCRIPT
CP BIO
Chapter 9Cellular Respiration
How Cells Harvest
Chemical Energy
All life activities need energy
a. Maintain homeostasis; do life functions
breathe, circulate blood
active transport, synthesize
molecules
regulate temperature, etc.
b. Physical and mental activity
c. Cells use energy in ATP molecules
CP BIO: Ch. 9 Cell Respiration
Food energy is measured in calories
calorie = energy needed to raise the temperature of one mL water 1 degree Celsius
Food labels: Calorie (Kcal) = 1000 calories
Basics of Cellular Respiration
• Breaks down glucose in many small steps• a biochemical pathway
• Energy released is stored in molecules of ATP– Each ATP has enough energy for one cell task
• One glucose molecule yields 36 ATP
Cells use ATP for energyATP - adenosine triphosphate
High-energy bond between phosphate groups
- breaks easily, bond energy is released
Energy is used by cell to do work
7
Phosphorylate - add a phosphate group to a molecule - transfers energy to new molecule
When cell needs energy for work, 3rd phosphate
comes off ATP and attaches to molecule doing work
8
ATP – ADP Cycle• ATP breakdown products (ADP + P) stay in cell
• used again to make more ATP when needed
ATP made in cell respiration
ATP used for cellular work
Very fast!! 10 million ATP/second in a cell
All organisms do respiration
• Need oxygen - aerobic
• No oxygen - anaerobic
Energy flow is one-way
- sun plants ATP
Chemicals recycle
Oxygen and EnergyAerobic respiration harvests the most ATP from glucose
Aerobic AnaerobicBreaks down glucose completely Glucose partly broken down
Yields max amount of ATP Yields only 2 ATP/glucose
Most organisms Only a few microorganisms
Products: CO2 , H2O Products: depends
3 stages of breakdown 2 stages of breakdown Glycolysis Glycolysis Kreb’s cycle Fermentation Electron Transport Chain
Mitochondria – “power house”Compartments
- for different stages• Matrix
– Space enclosed by inner membrane
• Inner membrane– Deeply folded, more surface – Many reactions at the same time
• Cristae - folds in membrane
• Intermembrane space– Between inner and outer
membrane
Gas exchange is by diffusionIn the lungs:
Oxygen from air- diffuses into blood- carried to body cells
Carbon dioxide from blood- diffuses into air sacs- removed from body
Cells need oxygen for respiration
In cells: - oxygen diffuses IN - CO2 goes OUT
Electron Acceptors
• Help in reaction pathway, re-used
• 2 in respiration: NAD and FAD
• Accept hydrogen ions and electrons
from glucose as it breaks down
• Transfer them to another molecule
later in pathway
–makes ATP
Stages of Cell Respiration
1. Glycolysis• In cytoplasm• Splits glucose in half
2. Kreb’s Cycle• In mitochondria• Finishes glucose
breakdown3. Electron Transport Chain
• In mitochondria• Generates the most ATP
Glycolysis 1st stage in cell respiration
Glycolysis = “sugar splits”
Glucose two smaller molecules
small amount of energy released
Need 2 ATP to start
a. Two ATP attach to glucose
b. glucose splits in two
c. 3-carbon PGAL forms
d. PGAL goes through several more reactions
e. PGAL becomes pyruvic acid
Glycolysis breakdown 1) Each PGAL loses hydrogen to NAD+
a) makes NADH
b) PGAL changes to pyruvic acid
2) 4 ATP are produced, but net yield is 2
Products of glycolysis:
1) 2 ATP
2) 2 NADH
3) 2 pyruvic acid
All organisms do glycolysis• Need no oxygen or special organelles
• Probably evolved very early in history of life
• Can meet energy needs of some simple organisms
Sir Hans Krebs 1900-1981
• German chemist, 1930s• Described the cycle of reactions that
make energy in cells
• Received Nobel in 1953
• “Krebs Cycle” or “Citric Acid Cycle”
Pyruvic Acid BreakdownPREPARES pyruvic acid for Kreb’s cycle
NOT a separate stage
1) Hydrogen removed NADH2) Carbon removed CO2
3) Acetyl-CoA forms4) Ready for Kreb’s cycle
Kreb’s Citric Acid Cycle Stage 2 in aerobic respiration
In MATRIX
Completes breakdown of glucose to carbon
dioxide
Makes many molecules of NADH
and FADH2
(make energy later)
Products of Kreb’s Cycle
1. 2 ATP/glucose molecule (one each “turn”)
2. Several molecules of NADH and FADH2
– These will yield energy in stage 3
3. Last carbons in glucose form CO2 and
diffuse out of cell
Electron Transport ChainStage 3 in aerobic respiration
• SAME AS ETC IN PHOTOSYNTHESIS
• Chain of proteins in inner membrane
• Take electrons from NADH, FADH
• Electron energy makes ATP
MOST ATP made in this stage
ETC in Respiration
Only happens if oxygen is available to take electrons at end of
chain and form WATER
O + 2 H+ + 2 e- H2O
Chemiosmosis and ATP
• ATP Synthase – enzymes in cristae
• Electron energy creates H+ concentration
• H+ ions diffuse through ATP synthase
• activate synthase enzyme
• make (synthesize) ATP
ADP + P ATP
1)Starting molecules NADH, FADH2 release H+ and
electrons
2)Electron energy pumps H+ across
membrane- Forms H+ gradient
3) H+ ions diffuse through ATP
synthase(chemiosmosis)
4) ADP + P ATP
5) Final electron acceptor is oxygen
O + H+ + e- H2O
Electrons power ATP synthaseenzyme makes ATP
Total ATP yield per glucose:
Glycolysis – 2 ATP
Krebs – 2 ATP
ETC - 32 ATP
Total = 36 ATP
Summary of Aerobic RespirationPathway Reactants Products # ATP Location
Glycolysis Glucose + Pyruvic Acid NADH
2 cytoplasm
Krebs Cycle
Acetyl CoA CO2 NADHFADH2
2 Mitochondrial matrix
Electron Transport
Chain
NADH,FADH2
O2
H2O 32 Mitochondrial cristae
Total ATP 36-38
Anaerobic Respiration
FERMENTATION follows glycolysis
– Needs no oxygen
– Makes no additional ATP after glycolysis
– NAD+ is reused
– Pyruvic acid is changed into a final product
Fermentation: two kinds
Alcohol lactic acid
Alcohol Fermentation
Some yeasts
• pyruvic acid ethyl alcohol + CO2
•Baking, brewing beer and wine
• CO2 gas makes bread dough rise, bubbles in beer and champagne
No more ATP made
Lactic Acid Fermentation• Pyruvic acid lactic acid
• Anaerobic bacteria -make lactic (and other) acids
• Commercial uses: cheese, yogurt, soy products, sauerkraut, vinegars
• Muscle cells – can do fermentation only temporarily
• lactic acids builds up “oxygen debt”
• Muscles fatigue, cramp
• With fresh oxygen: Lactic acid blood liver, changed back to pyruvic acid Kreb’s cycle
Other foods in respiration
Carbs are #1 choice for cell energy: 4 cal/g
Fats: twice the calorie store: 9cal/g
Proteins: LAST choice: – needed for many important roles 4 cal/g
-Fats and proteins are also broken down in many small steps-Amount of ATP depends on molecule
Photosynthesis – makes food
Light energy chemical energy
6 H2O + 6 CO2 C6 H12 O6 + 6 O2
Respiration – breaks down food for cell energy
C6 H12 O6 + 6 O2 6 H2O + 6 CO2
Energy in food energy in ATP
Photosynthesis and Respiration
Breathing supplies oxygen to cells1) Breathing brings oxygen into the body
2) Oxygen in lungs diffuses into blood
3) Blood delivers oxygen to all
body cells4) Oxygen is used in
cell respiration.
5) CO2 diffuses out of cells into blood
6) Blood carries CO2 back to lungs - exhaled
2) starting molecule – acetyl CoA
3) 4-C compound in matrix
4. Carbon “fixed” 6 C citric acid
5) two carbons CO2
6) one ATP forms
8) 4-C compound recycled
7) hydrogens removed - NAD, FADH reduced
1) Pyruvic acid is broken down to CO2
and acetyl (2-C) -- joins to coenzyme A