Autotrophs organisms use can make their own food Some autotrophs capture light energy from the sun in the process of photosynthesis Heterotrophs obtain energy from the foods they consume ID: 777730
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Slide1
Photosynthesis
Slide2Autotrophs & Heterotrophs
Autotrophs
– organisms use can make their own food
Some
autotrophs capture light energy from the sun in the process of photosynthesis
Heterotrophs
– obtain energy from the foods they consume
Slide3ATP & Energy
Structure of
ATP
ATP (Adenosine Triphosphate) – shuttles energy for
cells
ATP is composed of ribose (a sugar), adenine (a nitrogenous base), and three phosphate groups
Slide4ATP & Energy
The
bond between the terminal phosphate groups of ATP’s can be broken, releasing organic phosphate and leaving ADP (adenosine diphosphate
).
Energy
is released from ATP when the terminal phosphate bond is broken.
This
release of energy comes from the chemical change to a state of lower free energy (stabilizing), not from the phosphate bonds themselves.
Slide5ATP & Glucose
ATP is not good for storing energy for a long time.
Cells only have a small amount of ATP.
One Glucose can store more than 90 times more energy than one ATP.
Cells store glucose, and use glucose to regenerate ATP as needed (cellular respiration).
Slide6*
Photosynthesis
– process of capturing light
energy
from the sun to convert water & CO2 into oxygen and high energy carbohydrates (food, ex: glucose, starch, & other sugars)
Equation
:
Energy (light) + 6CO
2
+ 6H
2
O
6O
2
+ C
6
H
12
O
6
Slide7Investigating Photosynthesis
Van
Helmont’s
Experiment – do plant’s grow by taking material from the soil?
Found mass of dry soil
Planted a seedling, watered it at regular intervals until it grew to a mass of 75kg.
Found mass of soil to be unchanged
Concluded the mass the plant gained came from the water he added.
Partially correct, but did not determine where the carbon in the carbohydrate comes from
Slide8Slide9Priestley’s Experiment – oxygen is produced by plants
Determined that oxygen was required to keep a flame lit/burning.
Removed oxygen from a jar by placing a lit candle under it until the flame went out.
Then placed a sprig of mint in the jar (empty of oxygen)
After a few days, he found he could relight a candle in this jar and it would remain lit for a while!
Slide10Slide11Jan
Ingenhousz
– light is essential to photosynthesis!
Showed the effect observed by Priestley occurred only when the plant is exposed to light!
Together, Priestly and
Ingenhousz showed the plants need light and water to produce oxygen.
Slide12Photosynthesis Basics
– occurs in the chloroplasts of plants,
protists
, and some bacteria cells.
Chloroplast
– organelle where photosynthesis occursSurrounded by 2 membranes.
Thylakoid
– flattened sac made of membrane inside the chloroplast
Granum
– stack of multiple thylakoids
Stroma
– fluid that surrounds the grana and fills the chloroplast
Slide13Slide14B.
Pigments
– compound that absorbs light
1. Chlorophyll – pigment on thylakoid membrane that absorbs light for photosynthesisChlorophyll a – absorbs less blue and more red light; directly absorbs sunlight
Chlorophyll b
– absorbs more blue and less red light; helps chlorophyll a absorb light
Both chlorophyll a and b reflect green light
Caretenoid
– another pigment that absorbs blue and green light, but not orange; also helps
chlorophyl
a absorb light.
Slide15C. Photosynthesis is chemically the opposite of Respiration.
Respiration
Photosynthesis Uses glucose to make ATP 1st converts light to ATP
2
nd
uses ATP to make glucose
**Equations are also the reverse!
Slide16NAPDH
As chlorophyll absorb sunlight, their electrons become excited (gain a lot of energy).
These high energy electrons require a special carrier called NADP
+
NADP
+ holds and carries 2 high energy electrons, along with a H
+
ion to become
NADPH
Slide17Light-Dependent Reactions
–
first step of photosynthesis,
converts
sunlight to ATPOccurs on the thylakoid membrane.Light is absorbed by a chlorophyll.
The light energy provides electrons for the Electron
Transport Chain (chain of proteins).
The ETC
splits
water (H
+
& O
2
are released).
Some H
+
is added
to NADP
+
and
produces
NADPH
.
The O
2
is released to the atmosphere.
Slide18Slide19Chemiosmosis
A
lso
happens on the membrane of the
thylakoids. Rest of the H+ (from the splitting of water) drives ATP Synthase proteins to make
ATP
.
*
Chemiosmosis and the ETC happen at the
same
time
!!!
Slide20Slide21Slide22Calvin Cycle
– the
2
nd
step of photosynthesis
. Also called the Light-independent Reactions (used to be called Dark Reactions), as light does not play any direct role.Uses ATP to make Glucose
Slide23Steps of the Calvin Cycle
RuBP
(carbohydrate in plants) reacts with
NADPH
, CO2 (from the atmosphere), and ATP to make
Glucose
.
In
the final step,
RuBP
is remade so the cycle can occur again.
Slide24Slide25Factors Affecting Photosynthesis
Water
– is a needed raw material; shortage of water slows or even stops photosynthesis
Temperature
– photosynthesis relies on enzymes, which only function between 0
oC and 35o
C
Intensity of Light
– up to a specific level, as light intensity increases, so does the rate of photosynthesis