Transcript Cells and Energy

Cells Lecture III
Cells
and
Energy
Photosynthesis & Cellular
Respiration
Biology Standards Covered
1f ~ students know usable energy is captured
from sunlight by chloroplasts and is stored from
the synthesis of sugar from carbon dioxide
 1g ~ students know the role of the
mitochondria in making stored chemical-bond
energy available to cells by completing the
breakdown of glucose to carbon dioxide
 *1i ~ students know how chemiosmotic
gradients in the mitochondria and chloroplasts
store energy for ATP production

Photosynthesis

There are only two types of
organisms on this planet


Producers – living things that
make their own food as well as
food for other living things
Consumers – living things that
rely upon consuming another
organism for food (energy)

What are you?
Photosynthesis

Producers
An example of a producer
would be a plant and how
it “makes” food could be
through a process known
as photosynthesis
 This takes place in the
chloroplast organelle
inside of a plant cell

Photosynthesis

Photosynthesis – is the
process of using energy from
the sun to convert CO2 and
H2O into chemical energy in
the form of sugars

Sunlight radiates the Earth as
visible light that we see and is
made up of many different
colors (ROYGBIV)
 Red,
Orange, Yellow, Green, Blue,
Indigo, and Violet
Photosynthesis

Chlorophyll is a molecule in plants that
absorbs visible light from the sun
There are two types (Chlorophyll a and
Chlorophyll b )
 Together they absorb mostly red and blue
wavelengths of light while “reflecting” some
yellow and much of the green

 This
is why you see plant leaves as “green” because
of the ‘reflected’ color
Photosynthesis

Inside of the chloroplast are
two structures important to
photosynthesis
Grana – are stacks of
membranes that look like a stack
of pennies surrounded by
compartments called thylakoids
 Stroma – is the fluid
surrounding the grana inside of
the chloroplast

Photosynthesis

There are two stages to Photosynthesis

Light-dependent reactions (First)
 Chlorophyll
absorbs energy from sunlight and energy is
transferred along thylakoids, Water is broken down and
Oxygen is produced
 Energy that is carried along thylakoids is transferred in
molecules of ATP

Light-independent reactions (Second)
 Carbon
Dioxide is added to a cycle of chemical reactions
building larger molecules of sugars
 Energy, ATP, from the light-dependent reaction is used to
form these simple sugars
Photosynthesis in a Chloroplast
CO2 (gas) is used to
make the sugar Glucose
C6H12O6 is
Glucose, a
simple sugar
that feeds all
living things
Photosynthesis in Chloroplasts
Cellular Respiration
The mitochondrion and its role
in providing plants and
animals with energy
Chemical Energy for Organisms

ATP – Adenosine
triphosphate


An energy rich molecule
that provides all living
things with energy for
growth, repair, and
maintenance
ADP – Adenosine
diphosphate

Energy comes from the

This creates ADP
release of the 3rd phosphate
of ATP
What is ATP?
ATP is molecule that
acts like a chemical
form of electricity for
all living things!
 Without ATP, you
could not move, think,
breathe, or grow!

What is Cellular Respiration?
Cellular respiration is when chemical
energy is released from sugars and
other carbon based molecules to make
ATP ~ when oxygen is present
 This means that cellular respiration is
aerobic in that it needs oxygen to take
place

Energy Production’s 2 Stages
Glycolysis & Cellular Respiration
How does it work?

Cellular Respiration (stage 2) takes
place in a mitochondrion


Some cells have several
IMPORTANT! ~ Before cellular
respiration can take place ~
Food molecules MUST be broken down
into simpler molecules
 The break down of glucose into (2)
3~Carbon Sugars is called Glycolysis

 Glycolysis
occurs in the cytoplasm
Glycolysis
2 ATP are used to “start” Glycolysis and 4 ATP are made in the second
stage. That means Glycolysis yields a “net” of +2 ATP
Glucose
Glycolysis is anaerobic
because it does NOT require
oxygen to take place! This
happens in the cytoplasm
*
2
Pyruvic
acid
To the
electron
transport
chain
Cellular Respiration happens in
the Mitochondrion
2 Pyruvate
molecules
from
glycolysis
go into
Stage 1
The Kreb’s Cycle
aka. Citric Acid Cycle

STAGE 1: The Krebs Cycle
During stage 1 the (2) 3~Carbon
pyruvate molecules from Glycolysis enter
the mitochondria
 These molecules undergo a series of
chemical reactions and a small amount of
ATP is produced (2 ATP Molecules)
 The waste product of the Kreb’s Cycle is
6 CO2 (Carbon dioxide) molecules
 Energy is transferred to “power” Stage 2
of Cellular Respiration

The Kreb’s Cycle
generates NADH
and FADH2 that
are fed into
stage 2 ~
Electron Transfer
Phosphorylation
Stage 2 of Cellular Respiration

Stage 2: Electron Transfer Phosphorylation
Energy from Glycolysis and the Krebs Cycle enter
Stage 2 to “power” the reactions
 NADH and FADH2 are “spent” to create a H+ ion
gradient inside of a mitochondrion
 When these protons, H+ ions, “rush back in” to
the mitochondrion, it generates ATP!
 Stage 2 makes 32 ATP molecules!

 Glycolysis
and the Kreb’s Cycle each only made 2
Cellular Respiration & Glycolysis
H+ Proton Gradient Formation
The inner and outer
compartments of the
mitochondrion are
where the H+ ions
are “pumped” and
allowed back in for
ATP generation
H+ Proton Gradient Formation
ATP Generation through
ATP Synthase