Cells get energy from food through cellular respiration or fermentation. Photosynthesis captures energy from sunlight and converts carbon dioxide and water into oxygen and glucose, which plants use for energy and animals obtain by eating plants. Cellular respiration breaks down glucose to release energy, using oxygen and producing carbon dioxide. When oxygen is scarce, cells use fermentation to break down glucose without oxygen.

1. Cell Energy:Cell Energy:
Here Comes the Sun!Here Comes the Sun!

2. Cell EnergyCell Energy
 Why do youWhy do you
get hungry?get hungry?
 FeelingFeeling
hungry ishungry is
your body’syour body’s
way ofway of
telling youtelling you
that yourthat your
cells needcells need
energy!energy!

3. From Sun to CellFrom Sun to Cell
 Plants capture energyPlants capture energy
from the sun andfrom the sun and
change it into foodchange it into food
through a processthrough a process
calledcalled
PHOTOSYNTHESIPHOTOSYNTHESI
SS

4.  Food that plantsFood that plants
make suppliesmake supplies
them withthem with
energyenergy..
 This food alsoThis food also
becomes abecomes a
source of energysource of energy
for organisms thatfor organisms that
eat plants.eat plants.

5. PhotosynthesisPhotosynthesis::
 PhotosynthesisPhotosynthesis: process by which plants,: process by which plants,
algae, and some bacteria usealgae, and some bacteria use
SunlightSunlight
carbon dioxidecarbon dioxide
andand waterwater
to make foodto make food

6.  Chlorophyll is theChlorophyll is the
main pigmentmain pigment
used inused in
photosynthesisphotosynthesis
 It gives plantsIt gives plants
their green colortheir green color
 Chlorophyll isChlorophyll is
found infound in
chloroplastschloroplasts..

7.  Plants use the energy capturedPlants use the energy captured
by chlorophyll to changeby chlorophyll to change
CARBON DIOXIDE and WATERCARBON DIOXIDE and WATER
IntoInto FOODFOOD
CO2CO2 ++ ==

8.  The food is in the form of the simpleThe food is in the form of the simple
sugarsugar GLUCOSEGLUCOSE, which is a, which is a
carbohydratecarbohydrate
 The energy inThe energy in glucoseglucose is used by theis used by the
plant’s cellsplant’s cells
6CO6CO22 + 6+ 6 HH220 + light energy = C0 + light energy = C66HH1212OO66 + 6O+ 6O22

10. Getting Energy from FoodGetting Energy from Food
 AnimalAnimal cells have different ways of gettingcells have different ways of getting
energy from food such as:energy from food such as:
**Cellular respirationCellular respiration: uses oxygen to break: uses oxygen to break
down fooddown food
**FermentationFermentation: the breakdown of food: the breakdown of food
without the use of oxygenwithout the use of oxygen

11. Cellular RespirationCellular Respiration
 Respiration meansRespiration means
““breathingbreathing””
 MostMost complexcomplex
organisms, fromorganisms, from
cows to humans,cows to humans,
obtains energyobtains energy
through respirationthrough respiration

12.  During cellular respiration, food (suchDuring cellular respiration, food (such
as glucose) is broken down into carbonas glucose) is broken down into carbon
dioxide and water, and energy isdioxide and water, and energy is
releasedreleased
 Most of the energy released maintainsMost of the energy released maintains
body temperaturebody temperature

13.  Some of the energy is used to formSome of the energy is used to form
ATPATP (which supplies energy that fuels(which supplies energy that fuels
cell activities)cell activities)
 Most of the process of cellularMost of the process of cellular
respiration takes place in the cellrespiration takes place in the cell
membranemembrane of prokaryotic cellsof prokaryotic cells

14.  In the cells of eukaryotes, cellularIn the cells of eukaryotes, cellular
respiration takes place in therespiration takes place in the
mitochondriamitochondria
 The equation for cellular respiration isThe equation for cellular respiration is
almost a complete opposite ofalmost a complete opposite of
photosynthesis!photosynthesis!
CC66HH12120066 + 60+ 6022 -> 6CO-> 6CO22 + 6H+ 6H220 + ENERGY (ATP)0 + ENERGY (ATP)

15. Connection Between PhotosynthesisConnection Between Photosynthesis
and Respirationand Respiration
 Photosynthesis transforms energy from thePhotosynthesis transforms energy from the
sun into glucose, cells use carbon dioxide tosun into glucose, cells use carbon dioxide to
make glucose, and the cells releasemake glucose, and the cells release oxygenoxygen
 During cellular respiration, cells use oxygenDuring cellular respiration, cells use oxygen
to break down glucose and release energyto break down glucose and release energy
andand carbon dioxidecarbon dioxide
 Each process makes the materials that areEach process makes the materials that are
needed for the other process to occurneeded for the other process to occur
elsewhereelsewhere

16. FermentationFermentation
 Have you everHave you ever
felt thatfelt that
burningburning
sensation insensation in
your legyour leg
muscles whenmuscles when
you run?you run?

17.  When muscleWhen muscle
cells just can’tcells just can’t
get enoughget enough
oxygen foroxygen for
cellularcellular
respiration, theyrespiration, they
use the processuse the process
of fermentationof fermentation
to get energyto get energy

18.  One kind ofOne kind of
fermentationfermentation
happens in yourhappens in your
muscles andmuscles and
produces lactic acidproduces lactic acid
(this is why you get(this is why you get
muscle cramps—amuscle cramps—a
buildup of acid!)buildup of acid!)

19.  Another type ofAnother type of
fermentationfermentation
occurs in someoccurs in some
types oftypes of bacteriabacteria
and in yeastand in yeast

20.  In a general sense, fermentation is the
conversion of a carbohydrate such as sugar
into an acid or an alcohol. More specifically,
fermentation can refer to the use of yeast to
change sugar into alcohol or the use of
bacteria to create lactic acid in certain
foods. Fermentation occurs naturally in
many different foods given the right
conditions, and humans have intentionally
made use of it for many thousands of years.
 earliest uses of fermentation were most
likely to create alcoholic beverages such as
mead, wine, and beer.

21.  Fermentation is a way thatFermentation is a way that
cells get energy from theircells get energy from their
food without usingfood without using oxygenoxygen
 Yeast forms carbonYeast forms carbon
dioxide duringdioxide during
fermentation. The bubblesfermentation. The bubbles
of carbon dioxide gasof carbon dioxide gas
cause the dough to risecause the dough to rise
and leave small holes inand leave small holes in
the bread after it’s baked.the bread after it’s baked.