The Wonderful World of
Biology presents:
Cellular Respiration
LET’S START WITH
Photosynthesis
Photosynthesis
• Cells can not create their own energy,
but are able to absorb energy from
their surroundings.
• Photosynthetic cells acquire their
energy in the form of light, which they
use to make the organic compounds
that provide energy to other cells.
Photosynthesis
In the process of photosynthesis, plants use
the energy of sunlight to convert water and
carbon dioxide into high-energy
carbohydrates—sugars & starches—and
oxygen, a waste product.
Photosynthesis
6 CO2 + 6 H2O +
light
energy
pigments
C6H12O6 + 6 O2
This is a simple summary of a very complex
process. It is not a single process, but two,
each with multiple steps.
The 2 stages:
•Light reactions
•Calvin Cycle (dark reactions)
Light Reactions
Changes solar energy into chemical
energy
– Splits water molecules
– Produces O2
– Forms organic molecules (ATP & NADPH)
Calvin Cycle
Uses the organic molecules (ATP
& NADPH) from the light reactions
Uses CO2 from the air
Produces sugar—C6H12O6
Cellular Respiration
So…what IS cellular respiration?
Why is it important to cells?
What is Cellular Respiration?
The process of converting food
(chemical) energy into ATP energy
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + 36 ATP
Why are both Photosynthesis and Cell
Respiration important to Ecosystems?
Light is the ultimate
source of energy for
most ecosystems
Chemicals cycle and
Energy flows
Photosynthesis and
cellular respiration
are
complementary
reactions
Why do plants need both
chloroplasts and mitochondria?
Chloroplasts use
energy from the
sun to make
glucose
Mitochondria
convert glucose
to ATP—the
energy currency
of the cell
What is ATP?
Adenosine triphosphate
– 5-Carbon sugar (Ribose)
– Nitrogenous base
(Adenine)
– 3 Phosphate groups
Energy currency of the
cell
The chemical bonds that
link the phosphate groups
together are high energy
bonds
When a phosphate group
is removed to form ADP
and P, small packets of
energy are released
How is ATP used?
As ATP is broken down, it
gives off usable energy to
power chemical work and
gives off some nonusable
energy as heat.
Synthesizing molecules for
growth and reproduction
Transport work – active
transport, endocytosis, and
exocytosis
Mechanical work – muscle
contraction, cilia and flagella
movement, organelle
movement
Why use ATP energy and not
energy from glucose?
Breaking down glucose yields too much energy
for cellular reactions and most of the energy
would be wasted as heat.
1 Glucose = 686 kcal
1 ATP = 7.3 kcal
1 Glucose → 36 ATP
How efficient are cells at converting glucose into
ATP?
– 38% of the energy from glucose yields ATP,
therefore 62% wasted as heat.
Cell Respiration can be divided into 4 Parts:
1)
2)
3)
4)
Glycolysis
Oxidation of Pyruvate / Transition Reaction
The Krebs Cycle
The Electron Transport Chain and
Chemiosmotic Phosphorylation
Where do the 4 parts of Cellular
Respiration take place?
Glycolysis:
– Cytoplasm
Oxidation of
Pyruvate:
– Matrix
The Krebs Cycled:
– Matrix
Electron Transport
Chain and
Cheimiosmotic
Phosphorylation:
– Cristae
Parts of the Mitochondria
2 “types” of respiration:
Anaerobic respiration=fermentation
– Simple & yields energy quickly
– No O2 required
– Occurs in cytoplasm
– Net production of 2 ATP/molecule glucose
(in other words, 1 glucose = 2 ATP)
Anaerobic fermentation
Alcoholic
fermentation
– Bacteria & yeast
– Produces ethanol
and carbon
dioxide
Lactic acid
fermentation
– In animals
– Produces lactic
acid
Aerobic Respiration
Begins the same as anaerobic
– Glycolysis in the cytoplasm
– O2 not required for this stage
Added steps—require Oxygen
– Moves to the mitochondria
Kreb’s Cycle
Electron Transport Chain
– Net production of 36 ATP
(1 glucose = 36 ATP)
Yeast!!
Domain—Eukarya
Kingdom—Fungi
Yeast are the only (known) singlecelled fungi—and there are LOTS of
different species
Yeast!!
Can carry out both aerobic and
anaerobic respiration
Relatively easy to measure rate of
respiration…how???