Download Chapter 8 & 9 Photosynthesis & Cell Respiration

CHAPTER 8
PHOTOSYNTHESIS
ENERGY AND LIFE

Living things depend on energy

Sun is source of most energy

2 types of organisms,
–
–
AUTOTROPHS make their own food (Ex: plants,
bacteria*, protists*)
HETEROTROPHS get energy from the foods they
consume (animals, fungi)
Research On Photosynthesis
–
VAN HELMONT- determined in the 1600’s that
plants grew because of water.
–
PRIESTLEY- found that plants release oxygen.
–
JAN INGENHOUSZ- found aquatic plants produce
oxygen bubbles in the light, therefore plants need
sunlight to produce oxygen
AN OVERVIEW OF
PHOTOSYNTHESIS

Plants use the energy of
sunlight to
–
–
convert water & carbon
dioxide into high energy
carbohydrates (sugar)
oxygen is a waste product.
light
→C H
6H2O + 6CO2
Reactants
6
12O6
+ 6O2
Products
What Else Does The
Photosynthesizer Need?
 Chlorophyll-
a chemical
pigment that traps the energy
of the sun and converts it to
chemical energy
Capturing Light Energy



White light= ROY G BIV
Chlorophyll captures (absorbs) energy at the
ends of the spectrum (red/orange & blue/violet)
What you see is the wavelengths that are
reflected. (green)
2 Types of Chlorophyll


Chlorophyll a
Chlorophyll b
How Chlorophyll Works


Sunlight excites e-s in the chlorophyll
molecule.
These excited e-s perform the work of
photosynthesis.
Where Photosynthesis Occurs
 In
the chloroplast
CHLOROPLASTS




contain saclike
photosynthetic
membranes called
THYLAKOIDS
Thylakoids arranged
in stacks called
GRANA.
Surrounding grana is
a gel-like substanceSTROMA.
Photosynthesis
begins in thylakoid
membranes.
The Recipe of Photosynthesis
Photosynthesis Cycle and Teasers
Flow of energy in Photosynthesis

Sunlight energizes
the e-s in chlorophyll

Carriers are needed
to move these e-s (&
their energy) to fuel
photosynthesis

Carrier molecules
are used!
ANALOGY
 Fire heats up coals

Carrier is needed to
move these coals to
another place

A bucket is used!
e- Carriers & the e- Transport Chain
NADP+
(Nicotinamide adenine
dinucleotide
phosphate)

Accepts & holds a
pair of e-s & an H
atom to become
NADPH
ATP
(adenosine triphosphate)

Holds energy in the
bond holding the 3rd
phosphate
Photosynthesis is Many Reactions
Light-dependent rxns
 “"charging the
batteries"
 Location: thylakoid
membranes
 Reactants:H2O,
NADP+ & ADP
 Products: O2,
NADPH & ATP
Calvin cycle (lightindependent rxns)
 “Discharging your
batteries”
 Location: stroma
 Reactants: CO2,
NADPH, & ATP
 Products: Sugar,
NADP, & ADP
1. Summarize the
4. What is the function
light-dependent
of NADPH?
reactions
5. Why are the light
dependent reactions
2. What reactions make
important to the
up the Calvin Cycle?
Calvin Cycle?
3. How is light energy
converted into
chemical energy
during
photosynthesis?

Photosynthesis is Many Reactions
Light-dependent rxns
 Requires sunlight
energy
Calvin cycle (lightindependent rxns)
 Doesn’t require
sunlight energy!
ATP synthase

Is an enzyme (“-ase”
ending is a hint)



Is a membrane
protein.
It is a protein pump
that allows H+ ions to
pass thru the cell
membrane
This is necessary for
the formation of ATP
CHEMICAL ENERGY AND ATP




All living things use chemical energy
A chemical compound that cells use to store and
release energy is ATP (ADENOSINE
TRIPHOSPHATE).
ATP is like a fully charged battery ready to power the
machinery of a cell.
ATP powers many cellular activities Ex:
–
–
–
active transport across cell membranes,
protein synthesis
muscle contraction.
FACTORS THAT AFFECT
PHOTOSYNTHESIS

Amount of Water

Amount of CO2

Temperature

Intensity of Light

Wavelength of light
SUMMARY OF
PHOTOSYNTHESIS

The process of photosynthesis includes the
LIGHT-DEPENDENT REACTIONS as well as the
CALVIN CYCLE.


LIGHT DEPENDENT REACTIONS
– produce oxygen gas and convert ADP and NADP into
the energy carriers ATP and NADPH.
CALVIN CYCLE
– uses ATP and NADPH from the light-dependent
reactions to produce high energy sugars.
CHAPTER 9
CELLULAR RESPIRATION
(In the last chapter, we
learned how photosynthesizing organisms (such as
plants) take energy from
sunlight & trap it in sugar
(glucose) molecules.)
 Now we will learn how living
things release this energy to
fuel their daily activities.

CHEMICAL ENERGY AND FOOD

The CALORIE is used to measure the amount
of energy present in food.
.
“calorie” v. “Calorie”what’s the difference?

calorie- the amount of energy needed to raise
the temperature of 1 gram of water by 1 degree
Celsius.

Calorie- 1000 calories
–
–
More accurately named a “kilocalorie”
The unit used on food packages.
Quick Review of Organic Molecules
in Living Things




Carbohydrates (sugars, starches, etc.)
Proteins
Lipids (mainly fats)
Nucleic acids (ATP, NADP, RNA, DNA)
Where’s the Energy?



Energy is trapped in the chemical bonds in
organic compounds in food.
Ex: plants convert sunlight energy into
chemical energy in glucose (sugar)
When we break down glucose (& other organic
compounds), the energy is released again!
Cellular Respiration
 the
process living things use
to releases energy by
breaking down glucose and
other food molecules in the
presence of oxygen
Cellular Respiration
Cells do not “burn” glucose,
instead they slowly release energy
from glucose and other food
compounds
• They do this in many small stepsWHY?
If all the energy was released once,
•
it would be too much for the cell
and it would be destroyed!
Summary of Cell Respiration

Sugar + oxygen → water + carbon dioxide + energy

C6H12O6 + 6O2 → 6H2O + 6CO2 + energy
Cellular Respiration



ATP is the main molecule that is used to
provide direct energy for cell activities.
(electron carrier)
Remember, ATP is like a rechargeable battery.
Basically, the energy in 1 glucose molecule is
transferred into many ATP molecules to be
used little by little. (Kind of like breaking a
$100 bill into $1s or $5s to be used little by little
for purchases.)
Releasing Energy From
Glucose Step 1: Glycolysis
 GLYCOLYSIS
is the process in which
one molecule of glucose is broken in
half, producing two molecules of
pyruvic acid.

C6H12O6 → (2) 3-Carbon molecules (pyruvic acid)
–
(see Fig 9-3, p 223 of text)
Glycolysis, cont.
 GLYCOLYSIS
comes from the
Greek word glukus meaning “sweet”
and the Latin word lysis which
means decomposing.
 Thus
GLYCOLYSIS means
“breaking glucose”.
Glycolysis, cont.
 Takes
place in the cytoplasm
 Releases
a small amount of energy
– (2 ATP & 2 NADH) & H2O
 Is
ALWAYS the first step of
releasing energy from glucose.
SUMMARY OF GLYCOLYSIS
Reactants: Glucose, ADP, NAD+
Products: 2 ATP, NADH, H2O
WHAT FOLLOWS GLYCOLYSIS?
 AFTER
glycolysis, living things can
release more energy from sugar.
 How
they do it depends on
WHETHER OR NOT O2 IS
PRESENT.
Releasing Energy From Glucose:
Flow Chart
RED:
Fermen
tation
}
{
Red + Blue
= Cell
Respiration
Releasing Energy From Glucose
Step 2A: Fermentation
 When
O2 is not present,
GLYCOLYSIS is followed by a
process called FERMENTATION.
 “No air”=“Anaerobic Pathway”
 FERMENTATION releases a small
amount of energy from food by
producing ATP w/o O2
2 Types of Fermentation
1.
ALCOHOLIC FERMENTATION
produces carbon dioxide and alcohol.
This type of fermentation causes bread
dough to rise.
•
Reactants: pyruvic acid, NADH
Products: CO2 , alcohol (ethanol), NAD+
•
2 Types of Fermentation,
cont.
2. LACTIC ACID FERMENTATION is
produced in your muscles during rapid
exercise when the body cannot supply
enough oxygen to the tissues.

With rapid exercise your muscles run out
of oxygen. Your muscle cells rapidly
begin to produce ATP by LACTIC ACID
FERMENTATION
Fermentation

Also occurs in the
CYTOPLASM
Step 2B:KREBS CYCLE
Occurs
– when
O2 is present
(“aerobic”)
– In the mitochondria (the
powerhouse of the cell)
THE KREBS CYCLE

Pyruvic acid is converted into citric acid (Krebs is
also known as “Citric Acid Cycle”)

Citric acid is then broken down, releasing carbon
dioxide and many ATPs in a series of small
reactions

REACTANTS: O2, pyruvic acid, NAD+, FAD, ADP
PRODUCTS: CO2, NADH, FADH, ATP,

Energy Efficiency of
Cell Respiration
 about
38% of the total energy of
glucose is trapped in ATP & can be
used by the cell.
 The remaining 62% is released as heat,
which is why your body feels warmer
after vigorous exercise.
QUICK VS. LONG TERM ENERGY
 QUICK
ENERGY1. ATP stored in muscles-only
enough ATP for a few seconds of
intense activity
2. Lactic Acid Fermentation- when
the ATP is almost gone, the
muscles begin producing most of
QUICK VS. LONG TERM ENERGY
(cont.)

LONG TERM ENERGY- cellular respiration
is the only way to generate a continuing supply
of ATP.
–
C.R. produces a lot of energy BUT it does so more
slowly than fermentation
3. You have enough glycogen, (a
carb) in your muscles & other
tissues) for about 15 or 20
minutes of activity.
QUICK VS. LONG TERM ENERGY
(cont.)

LONG TERM ENERGY (CONT.)
4. After that, your body begins to
break down other stored
molecules including fats for
energy. This is why aerobic forms
of exercise like running, swimming
etc. are beneficial for weight
control.