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NUTRITION
Nutrition is the life function by which organisms obtain materials for energy,
growth, repair of tissues, and to generally carry out all life functions.
*Some organisms “make” their own food; they are called Autotrophic.
* Organisms that cannot produce their own food must find food; they are called
Heterotrophic organisms.
AUTOTROPHIC NUTRITION:
-The process in which plants and algae convert Carbon Dioxide, Water, and Sunlight
(with the help of enzymes) into Glucose and Oxygen. ****This is called
PHOTOSYNTHESIS***
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
*This process happens in the CHLOROPLASTS.
*Chlorophyll, found in the chloroplasts, absorbs light energy from the sun.
*The best wavelengths of light for photosynthesis are BLUE AND RED!
Green is actually reflected and therefore absorbed the least.
*The “goal” of Photosynthesis is to produce GLUCOSE ; C6H12O6 .
With the help of enzymes, CO2 and H2O are rearranged to form C6H12O6
Photochemical (light) Reaction:
-Stacked layers of chlorophyll containing membranes inside of a chloroplast are called
GRANA.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
*Light energy is absorbed by the chlorophyll and other pigments in the grana and is used
to split water molecules. This process is called PHOTOLYSIS (“splitting with light”).
The Hydrogen (from water) is picked up by a “hydrogen-carrier” compound –NADPHand is used in the next phase.
The Oxygen (from water) combines with other oxygen molecules released from
photolysis and becomes atmospheric oxygen.
** A radioactive isotope...Oxygen-18 was used to trace the path of oxygen**
* The ENERGY from the sun that was trapped by the chlorophyll is moved into an
energy carrying compound called ATP.
The ATP carries the energy to the next phase.
Carbon-Fixation (dark) Reaction:
Occurs in the Stroma of the chloroplast.
Hydrogen atoms (released from water and carried to this reaction from the light
reaction) are “fixed” onto the Carbon Dioxide compound. This results in the formation of
a 3-Carbon sugar; phosphoglyceraldehyde (PGAL).
** A radioactive isotope...Carbon-14 was used to trace the path of Carbon**
-PGAL’s are combined to form the 6-Carbon compound called Glucose (C6H12O6)
***The ENERGY carried by the ATP is transfered into “Chemical Bond Energy” in the
GLUCOSE.
Leaf Structure:
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
*****HETEROTROPHIC NUTRITION****
A series of steps needs to take place for Het.
nutrition to take place:
- Ingestion- Process in which organisms take
organic compounds (food) into their body.
-Digestion- Most food taken in by ingestion
is made of complex molecules that need to be broken down into simple molecules. ***
These
need to be small enough to fit into the
openings of the cell membrane.
Mechanical Digestion - food is physically
broken down. Chewing, tearing, grinding
Chemical Digestion -ENZYMATIC HYDROLYSIS
Enzymes and water are used to split
complex molecules apart.
Complex food molecule
End Product
Carbohydrates
simple sugars
Lipids
Fatty acids & glycerol
Proteins
Amino Acid
-Egestion- removal of those substances that
were ingested but could NOT be digested.
***Intracellular Digestion - food is digested
inside of the cell. ex) amoeba, paramecium
Phagocytosis - process in which an amoeba
engulfs its food by using pseudopods (false
arms). Some human white blood cells also
do this to kill bacteria!
***Extracellular Digestion -food is digested
OUTSIDE of a cell. ex) fungi, HUMAN!!