Overview of Photosynthesis - Weebly · 2018. 9. 9. · Overview of Photosynthesis Most autotrophs...
Transcript of Overview of Photosynthesis - Weebly · 2018. 9. 9. · Overview of Photosynthesis Most autotrophs...
Overview of Photosynthesis
Most autotrophs (organisms that
create their own food), make organic
compounds (sugars/glucose) using a
process called photosynthesis.
This process occurs only in plants.
Overview of Photosynthesis
Photosynthesis is the process in which light
energy is converted into chemical energy and
can be shown by the following equation:
Overview of Photosynthesis
Photosynthesis occurs in two
stages:
Light-dependent reactions
(requires light)
Light-independent reactions
(does not require light)
Phase One: Light Reactions (Light-
Dependent)
Plants must first
capture light. They
have special organelles
called chloroplasts
located in the leaves of
a plant that help them
to capture light energy.
Phase One: Light Reactions (Light-Dependent)
Chloroplasts contain specialized structures to help
them carry out the two part process of
photosynthesis.
Thylakoid: flattened, sac-like
membranes that are arranged in
stacks
Grana (granum): stacks of
thylakoids
Stroma: the fluid-filled space that
is outside the grana
Phase One: Light Reactions (Light-
Dependent)
The thylakoid membranes of a
plant’s chloroplasts hold pigments,
which are special light absorbing
molecules.
Plants appear green because of
chlorophyll pigments found in the
chloroplasts.
Phase One: Light Reactions (Light-
Dependent)
When there’s a change in
temperature in certain parts
of the US, chlorophyll
pigments begin to break
down. Other pigments called
carotenoids may bring out
shades of yellow, red, and
orange.
Phase One: Light Reactions (Light-
Dependent)
Light reactions take place in the
thylakoids of a plant cell and consist of
the electron transport chain (or ETC).
At the end of the light reactions, we
have formed the energy-storage
molecules NADPH and ATP.
Phase One: Light Reactions (Light-Dependent)
Phase 2: The Calvin Cycle (Light-
Independent)
Plants must convert NADPH and ATP into organic
molecules called glucose (sugar), that can be
used by the plant.
At the end of the Calvin Cycle, the plant has
formed sugars, which can be used for energy and
as building blocks for complex carbs, which
make up cellulose and provide support for the
plant.
The Calvin Cycle
Overview of Cellular Respiration
The function of cellular respiration is
to take glucose and use the energy
stored there to make ATP, which can
then be used by the cells to carry out
essential processes.
This process occurs in BOTH plants and
animals.
Overview of Cellular Respiration
Cellular respiration occurs in the
mitochondria of the plant or animal
cell, and can be shown by the
following equation:
Overview of Cellular Respiration
Cellular respiration occurs in two main
parts: glycolysis and aerobic respiration
Stage one, glycolysis, is considered
anaerobic because it does not require
oxygen.
Stage two, which includes the Krebs Cycle
and ETC, is considered aerobic because it
does require oxygen.
Phase One: Glycolysis (Anaerobic)
Glycolysis occurs in the cytoplasm
of the cell and is the process of
breaking down the glucose.
At the end of glycolysis, we have
formed ATP and pyruvate
molecules.
Phase Two: Aerobic Respiration (Krebs
Cycle & ETC)
The Krebs Cycle is often referred to as the
Citric Acid Cycle.
In the Krebs Cycle, the pyruvate molecules
are broken down because they still hold
most of the energy.
At the end of the Krebs Cycle, we are left
with carbon dioxide molecules, ATP, NADH,
and FADH2
Phase Two: Aerobic Respiration (Krebs
Cycle & ETC)
The NADH and FADH2 go on to be used by
the ETC to convert ADP to ATP.
The ETC produces most of the energy, or
ATP.
Phase Two: Aerobic Respiration (Krebs
Cycle & ETC)
In eukaryotic organisms (those made up of
more than one cell), the ETC produces 36
ATP that the organism can use for essential
processes.
In prokaryotic organisms (those made up of
only one cell), the ETC produces 38 ATP
that the organism can use for essential
processes.
Anaerobic Respiration
In the event oxygen is not present for the cell to undergo the Krebs Cycle and ETC, it will than do an alternate process called fermentation.
Fermentation produces less ATP molecules than aerobic respiration, so it is not as efficient.
Anaerobic Respiration
There are two types of fermentation: lactic-
acid fermentation which produces lactic acid,
and alcohol fermentation which produces
alcohol.
Organisms such as yeast and bacteria undergo
fermentation to produce beer, wine, cheese,
and yogurt.