Transcript Photosynthesis/ Respiration PPT

How is energy being obtained by the
organisms in this picture?
Autotrophs & Heterotrophs
(Review)

Plants are able to use light energy from the sun
to produce food. - Autotrophs
 Organisms that obtain energy from the foods
they eat . - Heterotrophs

Organisms use and store energy in the
chemical bonds of organic compounds.
 Remember that the energy stored in ATP is
released when ATP is converted into ADP.
Photosynthesis
The process by which plants, algae,
& some bacteria use sunlight,
carbon dioxide and water to produce
carbohydrates and oxygen.
Carbon Dioxide + Water + Sunlight & Chlorophyll = Glucose & Oxygen
6CO2 + 6H2O + Sunlight & Chlorophyll = C6H12O6 + 6O2
Reactants of Photosynthesis

Carbon Dioxide - Comes from all the animals
including us (it's what we exhale).

Water - Interacts with the other ingredients to
mix and make glucose.

Sunlight – trapped in the chloroplasts by
chlorophyll. Uses the energy to break apart
the parts of a cell they need to work with.
Without sunlight, the plants would not give off
oxygen.
Products of Photosynthesis

Glucose - The food that plants made from
photosynthesis. It is used as their food source
to make energy.
 Oxygen - What we use to make our own
energy - which in turn helps plants to also make
their energy in a cycle.
Chlorophyll – A green pigment in chloroplasts
that absorbs light energy to start
photosynthesis.

Disc-like sacs called “thylakoids” contain the
chlorophyll that absorbs light energy to start
photosynthesis.
Photosynthesis can be broken
down into 2 stages:
1.
2.
Light-Dependent Reactions –within the
thylakoid membranes
Calvin Cycle (“Light-Independent
Reactions) – Takes place in the space
outside the thylakoid membranes called the
“stroma.”
Light-Dependent Reactions

Use energy from sunlight plus water to
produce ATP, NADPH, and Oxygen.
 Takes place in the thylakoid membranes of
chloroplasts.
 ATP and NADPH are energy carriers.
ATP & NADPH

Are not stable enough to store energy
for more than just a few minutes.
So…
Calvin Cycle

Plants use the ATP and NADPH
from the light-dependent reactions
to produce high-energy sugars.
 These reactions do not require
light.
 6 carbon dioxide molecules from
the atmosphere are needed to
produce a single 6-carbon sugar.

The Calvin Cycle takes place in the stroma of
the chloroplast (outside the thylakoid
membrane).
Why do plants do this???

Plants use the sugars for
energy to build more
complex carbohydrates
such as starches and
cellulose. It needs these
for growth and
development!
Summary of Photosynthesis

Fill out your handout!
Cellular Respiration

Energy in food is stored as carbohydrates,
proteins & fats. Before you can use that
energy, it must be released and transferred
to ATP.

Cellular respiration is the process that
releases energy by breaking down food
molecules in the presence of oxygen.
Oxygen + Glucose
CO2 + H2O + Energy
3 Steps of Cellular Respiration

If cellular respiration took place in just one
step, all energy would be released at once
and our cells need to control this.
1. Glycolysis –
The process in which
one molecule of glucose is broken in half,
producing 2 molecules of pyruvic acid (a 3
carbon compound)
Glucose
C6
2 ATP
NADH
Pyruvate
Pyruvate
C3
C3
Glycolysis…

Takes place in the cytoplasm
 Net gain of 2 ATP
 Takes place without oxygen (anaerobic)
 NADH is formed (electron carrier)
Two Things Can Happen:

1. Anaerobic Respiration - If no oxygen is
present, pyruvate goes through a process
called “fermentation.”

2. Aerobic Respiration – If oxygen is present,
pyruvate enters the mitochondria and enters
the “Kreb’s Cycle.”
Fermentation –
Recycles the NAD+
that is needed to make ATP in the absence
of oxygen.
Pyruvate
2 ATP
CO2
Alcohol
(plants)
Lactic Acid
(animals)
~ Takes place in the cytoplasm

Lactic acid is produced in your muscles
during rapid exercise when the body cannot
supply enough oxygen to the tissues.

The buildup of lactic acid causes a painfull
burning sensation.
2. Krebs Cycle –
A stage of aerobic
(requires oxygen) respiration in which
pyruvate is converted into CO2, water and
ATP.
~ Takes place in the mitochondria


The Kreb’s Cycle is a continuous cycle of
electrons transferred to energy carriers.
Citric acid is broken down, CO2 is released (you
exhale it out), and ATP is released to be used in
cellular activities.
What happens to all of the high energy electrons???
3. Electron Transport Chain –
Takes place along the inner membrane of
the mitochondria.


A protein in the
membrane called ATP
synthase. These
enzymes convert ADP
to ATP.
34 ATP are produced
(Lots of energy!)
The Totals

In the absence of oxygen, glycolysis
produces just 2 ATP molecules per
glucose.

In the presence of oxygen, everything
changes.
 The Kreb’s Cycle & electron transport chain
allow the cell to produce 34 more ATP
molecules.
 36 total ATP!

18 times as much
can be generated
from glucose in the presence of oxygen.
 The final waste products are water and
carbon dioxide.

38% of the energy in glucose is used to make
ATP. 62% is released as heat. (This is why
you become warm when you exercise).
Comparing Photosynthesis &
Cellular Respiration
Photosynthesis
Function
Location
Reactants
Products
Equation
Cellular Respiration

Photosynthesis & Cellular Respiration are
almost opposite processes.
 Photosynthesis “stores” energy
 Cellular Respiration “releases” energy
 What do you notice about the equations????