Using Energy
Let’s review...7 characteristics of life?
1. All made of cells
2. All reproduce
3. All have a genetic code (DNA)
4. All grow and develop
5. All use energy
6. All respond to environment
7. All maintain homeostasis
What allows us to get up and walk out of class?
THE SUN!!!
We use energy to move muscles → get energy
from cell respiration → requires O2 to work →
get O2 from plants → plants go through
photosynthesis → needs the SUN to work!
ENERGY!
● Every living thing needs energy
● Plants get energy from….. THE SUN
○ Plants are called AUTOTROPHS
● Animals get energy from ….. FOOD
○ Animals are called HETEROTROPHS
Forms of Energy
● Remember physics??
○ Light
○ Heat
○ Electricity
Candle =
H + C in wax + O in air → H2O + CO2
-Releases energy as heat and light!
Cellular energy
● Adenosine triphosphate = ATP
○ Made of:
■ Adenine (remember from nucleotides!)
■ 5-carbon sugar (ribose)
■ 3 phosphates (triphosphate)
● There is also ADP
○ Only has 2 phosphates
ATP = “fully-charged” battery
ADP = “partially-charged” battery
Cell can store and release energy by changing
from ATP to ADP.
● Active transport (Low→High) uses ATP
● Cytoskeleton uses ATP to move organelles
● Photosynthesis and cellular respiration too!
CHLOROPLAST
MITOCHONDRIA
Plants → Photosynthesis → make glucose →
animals eat plants → cellular respiration →
break down glucose for energy!
Photosynthesis:
Cell Respiration:
-plants only!
-both plants/animals
-chloroplasts
-mitochondria
-stores energy (starch)
-releases energy
PHOTOSYNTHESIS
Carbon + Water + light
dioxide
→
Glucose
+ oxygen
(sugar)
6CO2 + 6H2O + light → C6H12O6 + 6O2
Main goal of photosynthesis = MAKE SUGAR!
Where do reactants come from?
CO2 : comes from air, animals breathe it out
H2O : comes from ground, roots soak it up
(capillary action!)
light : comes from the sun
Where do the products go?
C6H12O6 : used by plant for energy, make own
food
(forms starch!) → animals eat it!
O2 : put in air for animals to breathe...and some
stays in plant → plants/animals use it for
cellular respiration in mitochondria!
Gases like CO2 and O2 come in and out of cell
through holes called stomata.
-plants open them during day
-close them at night
● Occurs in chloroplasts
○ Found only in plants!
● Inside chloroplasts is a pigment = chlorophyll
○ Makes plants green!
○ Absorbs the sun’s energy
● Light energy is a wave!
○ Packets of light = photons
○ Captures red and blue
waves, reflects green - so
green is what we see!
● Fall = leaves turn red, orange, brown
○ Chlorophyll not being made, green not reflected
anymore
Structure of Chloroplast
● Individual sacs inside =
● Stack of sacs = Granum
● Region outside = Stroma
Thylakoid
1 cookie
Stack of cookies
Glass of milk
2 parts of Photosynthesis
Light-dependent
reactions
-day-time/sunlight
-happens in thylakoids
-H2O → O2
-makes ATP
Light-independent
reactions (dark)
-Calvin cycle
-happens in stroma
-CO2 → sugars
-uses that ATP
Light - dependent reaction
1. Light shines on plant
2. Energy waves reach chlorophyll molecules
inside thylakoids of chloroplasts
3. This excites electrons!
-These electrons come from the splitting of
H2O! Thylakoid steals electrons and ends
up forming O2!
4. Electrons jump to electron transport system
5. When they go through this system, it
generates ATP!
6. These “hot” electrons need carriers to move
them from chlorophyll to other molecules
-electron carrier = NADP+
-This molecule can hold onto 2
high-energy electrons
and a hydrogen ion (H+)
7. NADP+ gets changed to NADPH
● Filled with lots of energy!
NADP+ + 2e- + H+ → NADPH
At the end of LIGHT-DEPENDENT:
-ATP (energy)
-NADPH (electron carrier)
-O2
*ATP and NADPH leave thylakoid, enter stroma
Light - Independent Reaction
Happens with NO light (at night)
-continues as long as there is ATP,
NADPH from the dependent reaction
Also called the Calvin Cycle
1. CO2 from the air enters the stroma
2. Goes through chemical reactions
3. Lots of CO2 gets turned into glucose = C6H12O6
At the end of the LIGHT-INDEPENDENT:
-glucose!
-ADP (used up ATP energy)
-NADP+ (used up electron carrier)
*ADP and NADP+ leave stroma, enter
thylakoid again
Light-dependent
Light-independent (Calvin)
USES
PRODUCES
USES
PRODUCES
ADP
ATP
ATP
ADP
NADP+
NADPH
NADPH
NADP+
H2O
O2
CO2
C6H12O6
Sunlight
Factors affecting photosynthesis
Water shortage
-plants in desert
have waxy coating
Temperature
-too hot or too cold = denature enzymes
-can’t carry out Calvin cycle
Light intensity
-more light = faster rate of photosynthesis