Cell Respiration and Photosynthesis
Respiration: a process that occurs continuously in all organisms
-- It involves the transfer of the stored chemical energy in food molecules to a form
readily usable by organisms.
-- It usually also involves an exchange of gases between the organism and the
environment.
Cellular Respiration
-- those enzyme-controlled reactions in which the potential energy of organic molecules,
such as glucose, is transferred to a more available form of energy. (ATP)
ATP (adenosine triphosphate) -- a more available form of energy used by the cell
** When ATP is hydrolyzed, energy is released and ADP (adenosine diphosphate) is
formed. (The bonds between the phosphate groups are high in energy which is released
when these bonds are broken.)
** This energy can be used to power those metabolic activities which require energy.
HOH + ATP -------------> ADP + P + Energy
(ATP-ase)
** This reaction is reversible.
aerobic respiration: if molecular oxygen is used in the release of energy from ATP
anaerobic respiration: if molecular oxygen is not used
ANAEROBIC RESPIRATION
FERMENTATION
-- is carried on in some cells lacking the enzymes necessary for aerobic respiration
-- may be carried out in many other cells when oxygen is lacking
Lactic Acid Fermentation (Glycolysis)
-- glucose is gradually broken down in a series of enzyme controlled reactions to lactic
acid (anaerobic respiration)
Glucose --> 2 Lactic Acid + 2 ATP
-- Lactic acid is produced in animals and is associated with muscle fatigue.
-- Lactic acid is also produced by some bacteria and is important in the production of
cheeses, buttermilk, and yogurt.
** As a result of anaerobic respiration, there is a net gain of 2 ATP.
AEROBIC RESPIRATION
-- Many of the enzymes involved in aerobic cellular respiration are located in the
mitochondria.
-- In the process with the presence of oxygen, the chemical energy of glucose is released
gradually in a series of enzyme-controlled reactions.
-- Aerobic respiration is much more efficient than anaerobic respiration.
SUMMARY EQN:
glucose + oxygen ----------> water + carbon dioxide + 36 ATP
The energy from ATP is used by organisms to obtain, transform, and transport materials,
and to eliminate wastes.
2 Steps of cellular respiration:
1. Glycolysis: break down of glucose to two molecules of pyruvic acid. Product at the
end is a net gain of 2 ATP.

Takes place in cytoplasm
Glucose + 2 ATP --> 2 pyruvic acid + 4 ATP
2. Citric Acid Cycle: breaks down acetyl CoA to form ATP and CO2

Takes place in mitochondria
1. Electron transport chain: electron carriers (NADH and FADH) pass on
electrons to oxygen to yield 32 ATP molecules.
 Takes place in the inner membrane of the mitochondria
--------Cellular Respiration will yield a total of 36 ATP in the end---------
Photosynthesis:
Photosynthesis: process by which plants convert light energy to the chemical energy of
organic molecules (glucose)
The energy for life (photosynthesis) comes primarily from the Sun.
Word equation:
Carbon dioxide + water -------> glucose + oxygen
(sunlight) (enzymes)
chloroplasts: organelles that carry on photosynthesis
Contain:
1. Grana: pancake like stacks containing chlorophyl that convert light energy into
chemical energy. AKA..Thylakoid..Supported by protein liquid
2. Stroma: is an area inside of the chloroplast where reactions occur and starches
(sugars) are created.

protein liquid involved in the synthesis of organic molecules from CO2 and water
chlorophylls: variety of pigments within the chloroplasts
These chlorophyll pigments may be separated according to their various chemical
charges by a technique known as chromatography.
The glucose which is formed in photosynthesis may be:
1. Used as an energy source in cellular respiration.
2. Synthesized into other metabolic compounds. These compounds could include
proteins, DNA, starch, and fats. The chemical energy stored in the bonds of these
molecules can be used to provide energy for other life processes.
3. Converted into storage products by dehydration synthesis and other reactions.
** Algae and green plants are autotrophic organisms which carry on photosynthesis.
Some Factors which Influence the Rate of Photosynthesis
Increasing the level of CO2 tends to increase the rate of photosynthesis.
1.) Increasing the level of CO2 tends to increase the rate of photosynthesis.
2.) Limiting the amount of water to the extent of creating drought conditions will limit
the amount of photosynthesis.
3.) Increasing temperature from 0 C to 35 C tends to increase the rate of photosynthesis.
4.) Increasing temperatures over 35 C will decrease the rate of photosynthesis.
5.) Increasing light intensity will increase the rate of photosynthesis until a certain light
intensity is reached, after this intensity is reached, increasing the light intensity will have
no effect on the photosynthesis rate.
cuticle - the waxy, water-repelling layer on the outer surface of a leaf that helps
keep it from drying out (and protect it from invading bacteria, insects, and fungi). The cuticle
is secreted by the epidermis (including the guard cells) and is often thinner on the underside
of leaves. The cuticle is generally thicker on plants that live in dry environments.
epidermis - the protective, outler layer of cells on the surface of a leaf. The guard cells (and
stoma) are part of the epidermis. The surface of many leaves is coated with a waxy cuticle
which is secreted by the epidermis.
guard cell - one of a pair of sausage-shaped cells that surround a stoma (a pore in a leaf).
Guard cells change shape (as light and humidity change), causing the stoma to open and
close.
mesophyll - the chlorophyll-containing leaf tissue located between the upper and lower
epidermis. These cells convert sunlight into usable chemical energy for the plant.
palisade mesophyll - a layer of elongated cells located under the upper epidermis. These
cells contain most of the leaf's chlorophyll, converting sunlight into usable chemical energy
for the plant.
spongy mesophyll - the layer below the palisade mesophyll; it has irregularly-shaped cells
with many air spaces between the cells. These cells contain some chlorophyll. The spongy
mesophyll cells communicate with the guard cells (stomata), causing them to open or close,
depending on the concentration of gases.
stoma - (plural stomata) a pore (or opening) in a plant's leaves where water vapor and other
gases leave and enter the plant. Stomata are formed by two guard cells that regulate the
opening and closing of the pore. Generally, many more stomata are on the bottom of a leaf
than on the top.