Download ATP - cloudfront.net

Cellular Energy
Photosynthesis and
Cellular Respiration
A. Introduction
• Every living thing, plants, animals, needs energy
to do work which must be stored for use at any
time
→Energy is stored in molecule called
Adenosine triphosphate or ATP
o Composed of one adenosine molecule
and three phosphate groups
Adenosine
P
P
P
♦ phosphate groups (PO4 3-) are negatively
charged
– opposites attract, but LIKES REPEL!
Phosphate groups HATE being attached to
each other, so energy is stored in that
hateful bond
– when bond between phosphate #2 and
phosphate #3 is broken, lots of energy is
released which is then used by cell
– now is called adenosine diphosphate
or ADP
Energy
Adenosine
P
P
P
• Process of using energy from food is
called cellular respiration
→Both plants and animals use cellular
respiration to get their energy from
food, but how they obtain their food is
different
→Plants – sun
→Animals – plants
or other animals
o Plants: autotrophs that use
photosynthesis (food made using sunlight)
o Animals: heterotrophs that ingest or eat
(metabolism)
• Transfer of energy can be presented in a
pyramid
–
Quaternary
Each level only gets Consumer10% of energy
(h)
from previous level!
Tertiary
• Ex: primary
consumer only
Consumer
gets 1% of
(h) 0.01% sun’s energy
Secondary 0.1%
Consumer (h)
Primary Consumer
1% (heterotroph)
Primary Producer
10% (autotrophs)
100%
B. Photosynthesis
• Complex process in which visible
sunlight is converted into chemical
energy in carbohydrate (glucose)
molecules
o Process occurs within chloroplasts of
plant cell
♦ Divided into 3 stages that occur in
two areas of chloroplast:
– Thylakoid membrane (light-dependent
reaction: first two stages)
– Stroma (light-independent reaction: last
stage)
Chloroplast
o Light-dependent reaction (thylakoid)
♦ 1. Absorption of light energy
–Thylakoid in chloroplast contains
pigments chlorophyll and
carotenoids
>Water molecules split leaving H+
and O2 and freely moving excited
electrons (e-)
chlorophyll
H+ H
2
O
Oe 2
carotenoids
Thylakoid in chloroplast
Step 1 End Results
• H+ (hydrogen ion): from splitting water
• O2 (oxygen): from splitting water
• e- (electron): in everything, including
chloroplasts
♦ 2. Conversion of light energy
– Excited e- pass through series of molecules
along thylakoid membrane called electron
transport chain (ETC)
ee- e- - ee -e
e
e e
e-
ETC
– Causes H+ to be pumped into thylakoid lumen
AGAINST concentration gradient
> Of course, H+ will diffuse out of thylakoid
DOWN gradient making ATP
H+
H+
H+
H+ H+
H + H+ + H +
H
> Different ETC binds H+ with NADP+ (e- acceptor)
forming NADPH
 Forms ATP needed for energy in next steps
+
+
H
H
N
A
D
P+
eee- e-
ETC
e-
NADPH
H+
e-
e-
N
A
D
P+
NADPH
NADPH+
H
ATP!!
N
A
D
P+
Step 2 End Results
• NADPH: needed for next step
• ATP: energy needed for next step
End Results (1 & 2 so far…)
• Sunlight + H2O + NADP+  NADPH +
ATP + O2 (into atmosphere)
+
NADPH
+
+
ATP!!
N
A
D
P+
+

O2
• Light-independent reaction (stroma)
– 3. Storage of energy (Calvin Cycle)
• CO2 from atmosphere enters stroma, plus
NADPH, plus ATP makes glucose
–Process called Calvin cycle
–Carbon fixation
CO2 + NADPH + ATP  glucose
CO2
+
NADPH
+
ATP!
!

GLUCOSE
O
H
O
H C
C H
H
H
H
C6H12O6
O
O
H
C
H
H
O
C
C
C
H
H
O
H
Overview of Photosynthesis
Overview of Photosynthesis
Photosynthesis
Stage
Absorption of
Light
Conversion of
light (ETC)
Storage of
energy
(Calvin
Cycle)
Light
Start
End
Location
Products Products
Dependent
Thylakoid of
chloroplast
H2O, CO2,
light
H + , O2 ,
electrons
Dependent
Thylakoid
membrane
of
chloroplast
H+, NADP
ATP,
NADPH
Independent
Stroma of
chloroplast
CO2,
NADPH,
ATP
Glucose
(C6H12O6)
6CO2 + 6H2O + sunlight  C6H12O6 + 6O2
→Environmental factors can affect rate
of photosynthesis
o CO2
CO2
o H2O
o Sunlight
o Temperature (enzymes can get degraded
with excess)
C. Cellular Respiration
→Three stages that occur in different parts of
cell:
o1. Anaerobic glycolysis (cytoplasm)
o2. Aerobic Krebs cycle (mitochondria)
o3. Aerobic electron transport chain
(cristae of mitochondria)
o 1.Glycolysis
♦ Enzyme-assisted anaerobic (without
oxygen) process of breaking down glucose
into 2 ATP + 2 pyruvate
Glucose  2 ATP + 2 pyruvate

ATP
+
pyruvate
ATP
pyruvate
o 2. Krebs cycle (AKA citric acid cycle)
♦ Aerobic (with oxygen) process of making 2
ATP + e–Pyruvate + O2 makes 2 ATP
>If oxygen is absent, pyruvate gets
converted to lactate (in muscles) or
ethanol (in plants) in process called
fermentation
~ Lactate or lactic acid can build up in
muscle cells during vigorous anaerobic
exercise, and if not removed quickly
enough by blood, can cause muscle
cramps and/or soreness
~ Ethanol (drinking alcohol) can build up
in plants along with CO2
Pyruvate + O2  2ATP
pyruvate
+
O2

ATP
• 3. Electron transport chain (ETC)
– Additional ETC makes 32 ATP
ATP
ATP
ATP
ATP
e
e-
e-
e-
e-
e-
ATP
ATP
e-  32 ATP!
ATP
e-
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
Cellular Respiration
Cellular Respiration
Stage
Oxygen
Presence
Location
Start
End
Products Products
Glycolysis
Anaerobic
Cytoplasm
C6H12O6
2 ATP,
2 pyruvate
Citric acid
(Krebs) cycle
Aerobic
Mitochondria
O2 ,
2 pyruvate
2 ATP,
6CO2, e-
Lactic Acid
Fermentation
(animals)
Anaerobic
Cytoplasm
2 pyruvate
Lactic acid,
2 ATP, e-
Alcohol
Fermentation
(plants)
Anaerobic
Cytoplasm
2 pyruvate
Alcohol,
2 ATP, e-
Electron
Transport
Chain (ETC)
Aerobic
Cristae of
mitochondria
e-
32 ATP,
6H2O
C6H12O6+ 6O2  6CO2 + 6H2O + 36 ATP
Photosynthesis
& Respiration
THE END