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is the ability to do work
- is stored energy. Most important form is that
- stored in bonds of molecules
is energy of movement. Heat and light are examples of kinetic energy
Two Laws of Thermodynamics
- Law of Conservation of Energy:
- energy is neither created nor destroyed
2. Law of Entropy. Entropy is disorder
Chemical Reactions do one of
Store or Release heat
Reactions : Requires a net input of energy to get the reaction started.Photosynthesis is endergonic requires solar energy to drive the reaction. Stores the energy in the chemical bonds ofthe end product, glucose. Typically they store the energy input in the form ofhigh energy bonds • Potential energy of products (sugar) is greater than the potentialenergy of the reactants (CO2).
- Reactions Release energy. The amount of energy released in this reaction is
- equal to the difference in the potential energy of the reactants and the
- products. Exergonic reactions are energy-releasing.
- Potential energy of
- reactants (sugar) is greater than the potential energy of the products (CO2).
- Cell Respiration is exergonic: Burns food substances
- (lipids, carbohydrates, proteins) to form ATP and heat. Burning wood and fuel
- is exergonic burns carbon skeletons to form light and heat.
- is a protein molecule which serves as a biological catalyst, in lowering
- the energy of activation, thus speeding up the rate of reaction, without itself
- being chemically involved.
- This means they speed up the rate of a chemical rxn in the body without being
- consumed in the process. By lowering “activation energy” the reaction speeds up.
The name of an enzyme ends in ase. In general
- Lipids à glycerol and fatty acids
- Proteins à amino acids
- Maltose à glucose + glucose
are substances that bind to theactive site of an enzyme and inhibit the enzyme
2 kinds of Enzyme Inhibitors
- 1) Competitive: resembles the enzyme’s normal substrate and competes
- with it for binding to the enzyme’s active site.
- 2)Non-competitive: Binds outside the active site but changes the shape of the enzyme so that its active site no more fits the
- is the metabolic pathway that takes raw materials and converts it to
- sugar. Sugar is a form of chemical
- potential energy. It will be used by all consumers and by plants, during cell
- respiration, to make ATP (cell energy)
2 steps of photosenthesys
- The Light reaction: It uses the electrons from chlorophyll in a series of redox
- steps to make ATP and NADPH. These products are mandatory for the formation of
- The Dark Reaction: sugar is made from carbon dioxide using the energy of ATP and
- NADPH (made in the light reaction)
This means “Self Feeders”.
- are also known as Producers. They occupy
- the bottom Trophic Level in an Ecosystem and represent the large source of
- energy in the biotic component of an ecosystem.
location of photosenthesys
- takes place in the leaves in the chloroplast of the cells of plants.
- Photosynthesis occurs in Plants, and green protista and prokaryotes.
equation for photosenthesys
- carbon dioxide (Co2)+ H2o+Sunlight
- C6H12O6 (glucose)+Oxygen (O2)
Chloroplastis an organelle with a double membrane system.
- Outer membrane and inner membrane system called (thyllakoid membrane and
- grana stacks)
There are two phases ofphotosynthesis,
the light dependent and light independent reactions
- This is where sunlight energy is harvested and converted
- into cellular energy. It occurs in the thyllakoid
- membranes (grana stack) and requires pigments to harvest light. The light reaction.accomplishes the following.
- There are two energy generating
- units of the light reaction called Photosystem II and Photosystem I
- The two systems harvest light energy
- to produce a high energy electron.
- Splits water into 2H (e-) + 1/2O2 (this is the source of
- molecular oxygen)
- High energy electrons are released
- from chlorophyll molecules
- These electrons travel down the
- electron transport chain (a series of redox reactions) to make ATP & NADPH
NADPH is the final electron acceptor
- Both NADPH and ATP are needed to drive the DARK
- This stage is light dependent and
- only works in the presence of light
- = Dark Reactions: This is the sugar generating step. It occurs in
- the aqueous phase of the chloroplast called the “stroma”, is can occur in the
- presence or absence of light. The light
- independent reaction is also known as the Calvin Cycle.
- Calvin Cycle is a sequence of
- chemical reactions that produces Glucose from a 3-C compound, known as G3P.
- Carbon dioxide is fixed to a 5 C compound (Ribulose bisphosphate,RuBP) and
- forms an unstable 6C intermediate that immediately forms 2 molecules of G3P. G3P is the direct precursor to
- Glucose. During the Calvin Cycle carbon dioxide is reduced to Glucose. This is
- an uphill reaction and requires and input of energy (ATP and NADPH).
- is packets (photons) of electromagnetic radiation. Visible light is white light
- and is the light that plant pigments harvest for energy. The wavelengths of white light range from 400
- -750 nm, the shorter wavelengths are the most energetic while longer wavelength
- are the least energetic. Plants absorb mainly blue and red light and reflect
- green light.
- are used to harvest sunlight. They are lipid based, hydrophobic and are found
- in the thylakoid membranes of the chloroplast clustered in a complex called the
- reaction center. There are several types of photosynthetic pigments.
- Primary Pigments: These harvest
- the majority of the light. The green
- pigments called “Chlorophyll”. Prefer
- red (600-700nm) and blue (400-500nm). There are two chlorophyll molecules (A
- &B). It is chlorophyll a that releases the electron in response to specific
- wavelengths of light. Each absorbs maximally one specific wavelength of light
- (either 680 or 700 nm).
- b. Accessory Pigments. Non-chlorophylls. Harvest other wavelengths (colors) of
- light. Protect plant and chlorophylls
- from harmful light.
- These are small pores on the undersurface of leaves in plants. They are the
- site of Gas exchange. When the stomata
- are open mostly O2 and water vapor goes out and CO2 comes into the plant. On
- hot sunny days the plant may close its stomato to prevent water loss, when it
- does CO2 levels drop inside the plant.
THE EFFICIENCY OF PHOTOSYNTHESIS!