ap biology the point is to make atp! atp cell respiration – part 1!
TRANSCRIPT
AP Biology
The Point is to Make ATP!
ATP
Cell Respiration – Part 1!
AP Biology
Objectives: Understand the transfer of energy in
living systems Explain how easily ATP’s energy can be
transferred to do cell work. Demonstrate the difference between
anaerobic and aerobic respiration. Observe why energy must be extracted
in a step by step process rather than all at once.
AP Biology
Energy needs of life Organisms are endergonic systems
What do we need energy for?
synthesis (biomolecules) reproduction active transport movement temperature regulation
AP Biology
First Law of Thermodynamics The energy of the universe is constant It can be transferred or transformed It cannot be created or destroyed Principle of Conservation of Energy
AP Biology
Second Law of Thermodynamics Every energy transfer or transformation
increases the entropy of the universe.
AP Biology
3 Main types of work done by cells:
Mechanical work Transport work Chemical work
AP Biology
Exergonic Reactions Energy is released during the reaction Free Energy - G < 0 (neg)
AP Biology
Endergonic Reactions Energy is absorbed during the chemical
reaction G > 0 (positive)
AP Biology
energy
Where do we get the energy from? Work of life is done by energy coupling
use exergonic (catabolic) reactions to fuel endergonic (anabolic) reactions
+ + energy
+ energy+
AP Biology
Living economy Fueling the economy
eat high energy organic molecules (food) break them down = catabolism (digest) capture energy in form cell can use
Need an energy currency a way to pass energy around
ATPWhoa!
Hot stuff!
AP Biology
ATP Adenosine Triphosphate
modified nucleotide adenine + ribose + Pi AMP
AMP + Pi ADP
ADP + Pi ATP
an RNA nucleotide
How efficient!Build once,
use many ways
AP Biology
Why does ATP store energy?
PO–
O–
O
–O PO–
O–
O
–O PO–
O–
O
–OPO–
O–
O
–O PO–
O–
O
–OPO–
O–
O
–O PO–
O–
O
–O PO–
O–
O
–O
Each Pi group more difficult to add a lot of stored energy in each bond
most stored in 3rd Pi
∆G = -7.3 kcal/mole
Close packing of negative Pi groups
I think he’s a bit unstable… don’t you?
spring-loaded
instability of its P bonds makes ATP an excellent energy donor
AP Biology
How does ATP transfer energy?
PO–
O–
O
–O PO–
O–
O
–O PO–
O–
O
–O energyPO–
O–
O
–O +
Phosphorylation when ATP does work, it transfers
its 3rd Pi to other molecules ATP ADP releases energy
∆G = -7.3 kcal/mole it destabilizes the other molecule
Why is 3rd phosphate
like a baaad
boyfriend?
AP Biology
it’s never that simple!
An example of Phosphorylation… Building polymers from monomers
need ATP for energy & to take the water out
C
H
OH
H
OHC C
H
O
H
C+ H2O++4.2 kcal/mol
C
H
OH+ C
H
P+ATP ADP
-7.3 kcal/mol
H
OHC C
H
O
H
C+ +C
H
PPi
-3.1 kcal/mol
“kinase” enzyme
AP Biology
glucoseC-C-C-C-C-C
fructose-6PP-C-C-C-C-C-C-P
DHAPP-C-C-C
PGALC-C-C-P
2 ATP2 ADP
Another example of Phosphorylation… The first steps of cellular respiration
beginning the breakdown of glucose ATP
those phosphates sure make it uncomfortab
le around here
enzyme 1
enzyme 3 enzyme 4enzyme 5
enzyme 6
enzyme 2
AP Biology
ATP / ADP cycle
A working muscle recycles over 10 million ATPs per secondWhoa!
Pass me the glucose & oxygen!
Can’t store ATP too reactive transfers Pi too
easily only short term
energy storage carbs & fats are
long term energy storage
AP Biology
What’s the point? Cells spend a lot of time making ATP! ~ 1Billion ATP Molecules in every cell!!
“The point is to make ATP!”
I didn’t HEAR you!
Make ATP! That’s all I do all day. And no one
even notices!
AP Biology
The Point is to Make ATP!
ATP
What’s the point?
AP Biology
Harvesting stored energy Energy is stored in organic molecules
heterotrophs eat food (organic molecules) digest organic molecules
serve as raw materials for building & fuels for energy
controlled release of energy series of step-by-step enzyme-controlled reactions
“burning” fuels carbohydrates, lipids, proteins, nucleic acids
AP Biology
Harvesting energy stored in glucose Glucose is the model
catabolism of glucose to produce ATP
glucose + oxygen carbon + water + energydioxide
C6H12O6 6O26CO2 6H2O ATP+ + + + heat
CO2 + H2O + heatfuel
(carbohydrates)
combustion = making heat energy by burning fuels in one step
respiration = making ATP (& less heat)by burning fuels in many small steps
ATP
CO2 + H2O + ATP (+ heat)
res
pir
ati
on
AP Biology
How do we harvest energy from fuels? Digest large molecules into smaller ones
break bonds & move electrons from one molecule to another as electrons move they carry energy with them that energy is stored in another bond, released
as heat, or harvested to make ATP
+
e-
+e-
+ –loses e- gains e- oxidized reduced
oxidation reduction
AP Biology
How do we move electrons in biology? Moving electrons
in living systems, electrons do not move alone electrons move as part of H atom
+
H
+H
+ –loses e- gains e- oxidized reduced
oxidation reduction
C6H12O6 6O2 6CO2 6H2O ATP+ + +
oxidation
reductionH
AP Biology
Coupling oxidation & reduction Redox reactions in respiration
release energy as breakdown molecules break C-C bonds strip off electrons from C-H bonds by removing H atoms
C6H12O6 CO2 = fuel has been oxidized
electrons attracted to more electronegative atoms
in biology, the most electronegative atom? O2 H2O = oxygen has been reduced
release energy to synthesize ATP
C6H12O6 6O2 6CO2 6H2O ATP+ + +
oxidation
reduction
O2
AP Biology
Oxidation & reduction Oxidation
adding O removing H loss of electrons releases energy exergonic
Reduction removing O adding H gain of electrons stores energy endergonic
C6H12O6 6O2 6CO2 6H2O ATP+ + +
oxidation
reduction
AP Biology
How is the energy obtained from Glucose??
Watch the Video: Gummy Bear
Is it better to obtain energy from molecules all at once – or little by little??
Why??
AP Biology
If the energy is obtained all at once – the product is a thermodynamically unstable molecule
Energy obtained little by little will produce more stable products
AP Biology
The process of Cellular Respiration is a step by step process to extract energy from glucose while producing stable molecules
If it happened quickly – all energy would be lost as heat and light.
AP Biology
Glycolysis: First Step in Cellular Respiration Takes place in the cytoplasm One molecule of glucose is broken
down into two molecules of pyruvic acid
AP Biology
Energy from Glycolysis: 4 ATP are produced; however, it takes 2
ATP to start the process. Therefore, the net gain is 2 ATP
AP Biology
Glycolysis and Oxygen Does not require Oxygen = anaerobic Therefore, can provide some energy
during times when oxygen is not available.
AP Biology
Evolutionary perspective Life on Earth first evolved without
free oxygen (O2) in atmosphere energy had to be captured from
organic molecules in absence of O2
Organisms that evolved glycolysis are ancestors of all modern life all organisms still utilize
glycolysis
You mean, I’m related to them?!
AP Biology
Anaerobic Situation: During times when oxygen is not
available – the Kreb’s cycle and Electron Transport Chain cannot proceed
Energy from Glycolysis is used Energy from Fermentation (Lactic acid
or Alcoholic) is used if needed.
AP Biology
Lactic Acid Fermentation: Used by body to produce more energy
during times of less oxygen = anaerobic
Pyruvic Acid (from glycolysis) is converted into Lactic Acid
A steady supply of ATP is produced.
AP Biology
During times of rapid exercise (less oxygen) the body uses lactic acid fermentation for energy
Lactic acid build up causes your muscles to burn.
AP Biology
Energy tally so far??? 2 ATP were produced from glycolysis. 90% of the energy in a glucose
molecule still remains.
AP Biology
Is that all there is? Not a lot of energy…
for 1 billon years+ this is how life on Earth survived only harvest 3.5% of energy stored in glucose slow growth, slow reproduction
Heck of a way to make a living!
AP Biology
In the Presence of Oxygen: Pyruvic Acid will goes on to the Krebs
Cycle – to squeeze more energy out.
To Be Continued………..
AP Biology
Glucose…glucose