Download Cellular Respiration

Unit 4: BIOENERGETICS
Part 2: Cellular Respiration
Mrs. Howland
Biology 10
Rev. Oct 2015
Energy and Life
How do cells and living organisms maintain life?
REMEMBER:
Energy is the ability to do work
AUTOTROPHS make their own food
HETEROTROPHS
Eat plants
Eat other plant-eating animals
Absorb nutrients from decomposing organisms
(fungi, such as mushrooms)
Biochemical Pathways
Photosynthesis and cellular respiration are
biochemical pathways
Biochemical pathways are a series of chemical
reactions. The products of one reaction become
the reactants of the next
HARVESTING ENERGY
How does energy enter the food chain?
How do organisms use that energy to fuel their
systems?
Cellular Respiration
Releasing energy from the products of photosynthesis
Oxygen burns glucose to release carbon dioxide,
water, and ENERGY
ENERGY is released in the form of ATP
AMOUNT of Energy
The CALORIE
CALORIES are the UNITS used to express how
much energy is in food
CALORIE ~ amount of energy needed to raise
the temperature of 1 gram of water by 1 °C
Food labels use kilocalories
1 kilocalorie = 1000 calories
CALORIES per GRAM
Macromolecules
Different macromolecules have different
amounts of energy
Depends on their chemical structure and
bonding
The MITOCHONDRIA
2 of the 3 stages of CELLULAR RESPIRATION occur in the
Mitochondria
Parts of the MITOCHONDRIA
Identify the parts of the mitochondria
Parts of the MITOCHONDRIA
Identify the parts of the mitochondria
3 MAIN STAGES of Cellular Respiration
Glycolysis
Krebs cycle
Electron transport chain
The molecule we will use in our examples is:
GLUCOSE
The simple sugar!
STAGES of Cellular Respiration
How it all begins
Heterotrophs must take in energy from outside
sources
When heterotrophs take in (eat/consume) food
sources (glucose or other molecules such as
carbohydrates, proteins, and fats)-the foods
don’t already available in a form that can be
used right away!
Heterotrophs must convert the food into
usable energy
OVERVIEW of Cellular Respiration
Cellular Respiration is the transformation of
chemical energy in food into chemical energy
cells can use: ATP
The reactions proceed the same way for both
plants and animals. (Animals use consumed
foods, plants use self-made and stored food)
Overall Reaction:
C6H12O6 + 6O2 → 6CO2 + 6H2O
OXYGEN
“Respiration” means “breathing”
THE CONNECTION ~ Most of the biochemical pathways that
release energy from foods need oxygen
Breakdown of glucose begins in the cell’s
cytoplasm
Then splits into one of TWO (2) PATHWAYS:
AEROBIC Cellular respiration
ANAEROBIC Cellular respiration
AEROBIC RESPIRATION
AEROBIC Respiration ~ requires OXYGEN
Krebs Cycle
Electron transport chain
Electron transport chain directly requires
oxygen
Krebs cycle NEEDS electron transport chain to
function
ANAEROBIC RESPIRATION
Anaerobic Respiration ~ does not REQUIRE
oxygen
Glycolysis
Its final products are used as reactants for the
AEROBIC respiration steps
STAGES OF CELLULAR RESPIRATION
WHERE Cellular Respiration Occurs
GLYCOLYSIS ~ Cytoplasm
KREBS CYCLE ~
Mitochondria
ELECTRON TRANSPORT
CHAIN ~ Mitochondria
GLYCOLYSIS
Glycolysis is the first
stage of cellular
respiration
Glucose is broken down
into TWO (2) molecules of
pyruvic acid (a 3-carbon
molecule)
Pyruvic acid is a
REACTANT in the Krebs
cycle.
ATP and NADH are
produced (NADH is passed on
to Electron Transport Chain)
GYCOLYSIS ~ STAGE 1
What’s so great about GLYCOLYSIS?
Produces ATP very fast
Helpful when the cell has increased energy
demands
Does not require oxygen
KREBS CYCLE ~ STAGE 2
Occurs in mitochondria
WITH OXYGEN present, PYRUVIC ACID from
glycolysis is passed on to KREBS CYCLE
Pyruvic acid is broken down into carbon dioxide
(CO2) in series of reactions
The series of reactions release energy
Also known as ‘citric acid cycle’
The Krebs Cycle
Krebs cycle is the 2nd
stage of cellular
respiration
Reactants: Pyruvic Acid
(produced by glycolysis)
Products: ATP and CO2
(Citric acid is first
compound formed in
series of reactions)
Energy Extraction
during Krebs Cycle
During the series of
reactions, ENERGY
is released by the
breaking and
rearranging of
carbon bonds
Energy is captured in
the forms of ATP,
NADH, and FADH2.
Krebs Cycle uses Electron Carriers
Electron carriers
NAD+ and FAD
each accept pairs of
high-energy
electrons
Form NADH and
FADH2
NADH and FADH2
are used in the
electron transport
chain to generate
ATP
Overview ~ Krebs Cycle
Electron Transport and ATP Synthesis
Q: How does the electron transport chain use
high-energy electrons from glycolysis and the
Krebs cycle?
A: The electron transport chain uses the highenergy electrons from glycolysis and the Krebs
cycle to convert ADP into ATP.
Electron Transport
1) NADH and FADH2 pass their high-energy electrons to
electron carrier proteins in the electron transport
chain
2) At the end of the electron transport chain, the
electrons combine with H+ ions and oxygen to form
water
3) Energy generated by the electron transport chain is
used to move H+ ions against a concentration
gradient across the inner mitochondrial membrane
and into the intermembrane space
4) H+ ions pass back across the mitochondrial
membrane through the ATP synthase, causing the
ATP synthase molecule to spin
5) With each rotation, the ATP synthase attaches a
phosphate to ADP to produce ATP.
Overview ~ Electron Transport Chain
Cellular Respiration
~ TOTAL ENERGY PRODUCTION~
The complete breakdown of glucose results in
36 molecules of ATP
Glycolysis, Krebs Cycle, and Electron Transport
Chain all work together as the THREE (3) Stages
ANY food molecules can be broken down,
including proteins and lipids
OXYGEN ~ Can we get on without
it?
What happens if oxygen is not available to help
us extract energy from food molecules?
Can our cells use another pathway?
In the absence of oxygen, fermentation
releases energy from food molecules by
producing ATP
FERMENTATION
When conditions are ANAEROBIC, fermentation
becomes the next step after glycolysis
Fermentation converts NADH back into NAD+
NAD+ cycles back to glycolysis, which continues
to produce ENERGY
TYPES OF FERMENTATION
Alcoholic Fermentation
Lactic Acid Fermentation
ALCOHOLIC Fermentation
Used by yeasts and other microorganisms
Produces ethyl alcohol and carbon dioxide
(CO2)
What makes BREAD rise! Also makes alcoholic
beverages.
Alcoholic Fermentation
Chemical equation:
Pyruvic acid + NADH  Alcohol + CO2 + NAD+
LACTIC ACID FERMENTATION
Used by most organisms
Converts pyruvic acid into NAD+
NAD+ cycles back to glycolysis, which continues
to produce ENERGY
Chemical equation:
Pyruvic acid + NADH  Lactic acid + NAD+
Energy and Exercise
How does the body produce ATP during different
stages of exercise?
For short, quick bursts of energy, the body
uses ATP already in muscles as well as ATP
made by lactic acid fermentation.
For exercise longer than about 90 seconds,
cellular respiration is the only way to continue
generating a supply of ATP!
Quick Energy
Cells normally contain small amounts of ATP
produced during cellular respiration
Enough for a few seconds of intense activity!
Lactic acid fermentation can supply enough
ATP to last about 90 seconds
Extra oxygen is required to get rid of the lactic
acid produced.
Following intense exercise, a person will huff
and puff for several minutes in order to pay
back the built-up “oxygen debt” and clear the
lactic acid from the body! Phew!!!
Long-Term Energy
INTENSE exercise lasting longer than 90
seconds: cellular respiration is required to
continue production of ATP
Cellular respiration releases energy more slowly
than fermentation
The body stores energy in the form of the
carbohydrate glycogen. These glycogen stores
are enough to last for 15 to 20 minutes of
activity.
After that, the body begins to break down other
stored molecules, including fats, for energy.
Long-Term Energy
Hibernating animals like this brown bear rely
on stored fat for energy when they sleep
through the winter.
Compare and Contrast