Transcript How is life synthesized from non

Examining the processes of
photosynthesis and cellular respiration
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Autotrophs are producers that can make their
own food from inorganic substances, using
sunlight or other energy to fuel the reaction.
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There are two main types of autotrophs:
◦ Photoautotrophs- require photons from the sun to
carry out their oxidative reactions,
 cyanobacteria and plants are most famous
◦ Chemoautotrophs- do not require the sun to carry
out their oxidative reactions,
 Bacteria that live in extreme conditions (sulfur
vents etc.)
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Bacteria (prokaryotes – no nucleus) were first
form of life on Earth.
Early Earth environment very extreme
conditions.
Probably used inorganic molecules such as
sulfur and iron compounds to fuel energy
production through internal chemical
reactions (metabolism).
In the struggle for survival (the winners
reproduce most) efficient use of energy is
vital.
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Many complex organic molecules form from
simpler molecules.
Cells that produce a molecule like chlorophyll
that can harvest the sun’s energy provide a
huge survival advantage.
Natural selection – organisms that have
favorable traits in a particular environment
are more likely to produce more offspring
and pass on the favorable trait.
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Photosynthetic organisms out compete
chemosynthetic organisms at the Earth’s
surface.
Waste oxygen produced by photosynthetic
organisms (cyanobacteria) makes the Earth’s
atmosphere poisonous to the chemosynthetic
organisms.
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This theory proposes that eukaryotic cells
arose from symbiosis among several
prokaryotic cells.
What evidence is there to support this idea?
◦ Mitochondria and chloroplasts contain DNA that is
similar to bacterial DNA.
◦ They also have ribosomes similar to bacterial
ribosomes
◦ Like bacteria, mitochondria and chloroplasts
reproduce through binary fission, but eukaryotic
cells divide by mitosis.
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Changes in the
contents of the
atmosphere…
Changes in habitable
places as the ability to
photosynthesize
became common-place
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As conditions on
the planet changed,
populations needed
to adapt in order to
survive.
Adaptations are
inherited characteristics that increase
an organism’s
chance of survival.
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is a process
involves CO2, H2O and sunlight as reactants
in a chemical reaction
produces C6H12O6 and O2 as products.
Where and how does this take place?
Use your textbook, pg 596
to label these parts…
• xylem
•Phloem
•Epidermis
•Palisade mesophyll
•Cuticle
•Stoma
•Spongy mesophyll
•Guard cells
Does this look
familiar?
Working with your
table partners,
identify each cell part
and summarize the
function of each.
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inside the chloroplast of a eukaryotic
plant cell…
◦ the structure of the chloroplast is
adapted in ways that facilitate the
photosynthetic process,
◦ pigments in the chloroplast absorb and
reflect different wavelengths of sunlight
to make photosynthesis possible.
___ CO2 + ___ H2O
(reactants)
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Sunlight
___ C6H12O6 + ___ O2
(products)
Can you balance the chemical equation?
Because sunlight is such an essential ingredient in this
equation, cells have adapted structures that help to absorb
the sunlight and use it to trigger the chemical reaction
above…
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Use the concept map to help you map the steps of this
reaction
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Is the ability to
photosynthesize an
example of an
adaptation?
◦ If so, how?
◦ If not, why not?
How does
photosynthesis
increase an
autotroph’s chance of
survival?
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Amino acids -> polypeptides (precursors of
proteins) -> coacervate molecules (clusters of
macromolecules surrounded by a shell of water
molecules) -> nucleic acids (self-replicating
and subject to natural selection) -> lots more
time…
◦ Prokaryotic autotrophs
 Lack an inner membrane around nucleus, small…
ex: bacteria
◦ Eukaryotic autotrophs
 Have membrane organelles like chloroplasts…
ex: plants