Studied by 5 peopleways that organisms gain energy from enviroment
by harvesting energy through sunlight (phototrophs)
by harvesting energy from chemical compounds (chemotrophs)
difference between catabolism and anabolism
catabolism is set of chemical reactions that break down macromolecules into smaller units (releasing energy ATP)
anabolism is set of chemical reactions that build macromolecules from small units and require input energy (ATP)
Metabolism
set of biochemical reactions that transform molecules and transfers energy
kinetic energy
energy of motion
potential energy
stored energy
ATP (adenosine triphosphate)
energy-carrying molecule, captures energy obtained from food breakdown and releases it to fuel other cellular processes
what is the core of AtP
adenosine
what is the relationship between strength of a covalent bond and amount of chemical energy it contains?
chemical energy is a form of potential energy. the Stronger the covalent bond, the less chemical energy it contains, and weaker the covalent bond, the more chemical energy it contains
thermodynamics
branch of physics that deals with relationship between heat and other forms of energy
first law of thermodynamics
energy is neither created nor destroyed (constant amount of energy)
second law or thermodynamics
transformation of energy is associated with an increase in the degree of disorder in the universe
Entropy
the amount of disorder is a system
disorder
when kinetic energy is changed from potential energy, the amount of disorder increases
chemical reaction
involve the breaking and forming of bonds
Gibbs free energy (1)
the amount of energy available to do work
Gibbs free energy (2)
in chemical reaction we can compare the free energy of a reactants and products to determine wither the reaction releases energy that is available to do-work (free energy of product - free energy of the reactants
Exergonic
Chemical reactions with a negative G, that release energy
Endergonic
A chemical reaction that with a positive G, that requires the input of energy in order to proceed.
spontaneous
reaction releases energy
Enthalpy
The total amount of energy in a system
Entropy
A measure of disorder or randomness.
equation for total amount of energy
(H) = energy available to do work (G) + energy lost to entropy (TS)
absolute temperature
temperature measured on the kelvin scale
how to determine if the reaction is spontaneous or not?
The absolute values of the energy and enthalpy changes determines whether G is positive or negative (spontaneous or not)
relationship of energy equation
if G is positive H is positive, TS is negative
if G is negative His negative, TS is positive
Hydrolysis reaction example
ATP + H2O→ ADP + Pi (inorganic phosphate)
hydrolysis
chemical reaction, where water molecules split into a proton (H) and hydroxide (OH)
energetic coupling
The driving of a non-spontaneous reaction (POSITIVE G) by a spontaneous reaction (NEGATIVE G) the net G of the two reactions is negative
how does increasing the temperature affect the change in free energy (G) of a chemical reaction ?
increasing the temperature, increases value of TS, which decreases G. Meaning increasing temperature will make it more likely that a reaction will proceed without a net input of energy
How can hydrolysis of ATP drive non spontaneous reactions in a cell ?
the hydrolysis of ATP releases energy. This energy can be used to drive non spontaneous reactions if the total (G) of the entire path is negative
Enzymes
protein that functions as a catalyst to accelerate the rate of a chemical reaction
allosteric enzymes
an enzyme that is activated or inhibited when binding to another molecule changes its shape
cellular respiration
a series of catabolic reactions that convert energy in fuel molecules (glucose) into ATP (produces carbon dioxide as waste)
aerobic respiration
Respiration that requires oxygen
anaerobic respiration
Respiration that does not require oxygen
cellular respiration equation
C6H12O6 + 6O2---> 6CO2 + 6H2O + ATP
what molecules have a large amount of potential energy
carbohydrates, and lipids
What molecules have less potential energy in their bonds?
carbon dioxide and water
substrate-level phosphorylation
A way of generating ATP in which a phosphate group is transferred to ADP from an organic molecule, which acts as a phosphate donor or substrate. (only produces 12% of ATP)
oxidative phosphorylation
The production of ATP using energy derived from the redox reactions of an electron transport chain; the third major stage of cellular respiration. (produces 88% of ATP)
electron carriers
A molecule that carries electrons (and energy) from one set of reactions to another.
electron transport chain
A sequence of electron carrier molecules (membrane proteins) that shuttle electrons during the redox reactions that release energy used to make ATP.
oxidation-reduction reaction
reaction involving the loss and gain of electrons between reactants
oxidation
loss of electrons
reduction
gain of electrons
two important electron carriers are.....
nicotinamide adenine dinucleotide, and adenine dinucleotide
Stage 1 of cellular respiration
glucose, is partially broken down to produce pyruvate, and energy is transferred to ATP and reduced electron carrier (glycolysis)
stage 2 of cellular respiration
pyruvate is oxidized to another molecule called acetyl-coenzyme A, producing reduced electron carriers and releasing carbon dioxide
stage 3 of cellular respiration
acetyl-CoA is broken down and carbon dioxide is released
Stage 4 of cellular respiration
set of metabolic reactions that occur by passing electrons along an electron transport chain to the final electron acceptor, oxygen large amount of ATP is produced
change in free energy in cellular respiration
glucose is oxidized through a series of chemical reactions, releasing energy in the form of ATP and reduced electron carriers
Glycolysis
in eukaryotes takes place in the cytoplasm
pyruvate oxidation, the citric acid cycle, and oxidation phosphorylation
takes place in the mitochondia
glucose is anaerobic
because oxygen is not consumed
what is the overall equation of glycolysis
Glucose + 2ADP + 2NAD+ +2Pi --> 2ATP + 2pyruvate + 2NADH +2H20 + 2H+
At the end of glycolysis, but before the subsequent stages in cellular respiration, which molecules contain some of the chemical energy held in the original glucose molecule?
at the end of glycolysis, the energy in the original glucose molecule is contained in pyruvate, ATP, and NADH
Mitochondria
rod shaped organelles surrounded by a double membrane
the oxidation of pyruvate connects glycolysis to the __________________ cycle
citric acid cycle
intermembrane space
the space between the inner and outer mitochondrial membranes
mitochondial matrix
the space enclosed by the inner membrane of the mitochondria
pyruvate is transported into the ____________________, where it it converted into acetyl-CoA
mitochondrial matrix
the synthesis of one molecule of acetyl-CoA from pyruvate results in the formation of
one molecule of carbon dioxide, and one molecule of NADH
At the end of pyruvate oxidation, but before the subsequent stages of cellular respiration, which molecules contain the energy held in the original glucose molecule?
at the end of pyruvate oxidation, the energy in the original glucose molecule is contained in acetyl-CoA and NADH.
During the citric acid cycle:
fuel molecules are completely oxidized, acetyl-CoA is completely oxidized to a carbon dioxide
citric acid cycle is also called
the kerbs cycle, and the TCA cycle
citric acid cycle produces:
one ATP, three NADH, and one FADH2
At the end of the citric acid cycle, but before the subsequent stages of cellular respiration, which molecules contain the energy held in the original glucose molecule?
at the end of the citric acid cycle, the energy in the original glucose molecule is contained in ATP, NADH, and FADH2
electron transport chain:
is made up of four large protein complexes, that are embedded in the inner mitochondrial membrane
the mitochondrial membrane
consists of the highest concentrations of protein found in eukaryotic membranes
oxygen accepts electrons at the end of the electron transport chain and is:
reduced to from water O2 + 4e + 4H ----> 2H2O
O2 + 4e + 4H ----> 2H2O
catalyzed by complex IV
protein gradient have two components
chemical gradient that results from the difference in concentration
electrical gradient that results from the difference in charge between the two sides of the membrane
oxidation of the electron crarriers NADH and FADH2, leads to
the generation of a proton electrochemical gradient. This gradient is a source of potential energy used to synthesis ATP
animals breathe in air that contains more oxygen than the air they breathe out. Where is oxygen consumed?
oxygen is consumed in cellular respiration. Oxygen is the final electron acceptor in the electron transport chain and is converted to water
ATP synthase
an enzyme that couples the movement of protons through the enzyme with the synthesis of ATP
When oxygen is present
pyruvate is converted to acetyl-CoA, which then enters the citric acid cycle
When oxygen is not present
pyruvate is metabolized along a number of different pathways, played an important role in the early evolution of like on earth
Fermentaton
variety of metabolic pathways that produce Atp from the partial oxidation of organic molecules without oxygen
Two major fermentation pathways are
lactic acid fermentation and ethanol fermentation
lactic acid fermentation
occurs in animals, and bacteria, electrons from NADH are transferred to pyruvate to produce lactic acid and NAD
lactic acid fermentation equation
Glucose + 2 ADP+ 2 Pi→ 2 lactic acid +2 ATP+2H2O
ethonal fermentation
occurs in plants and fungi, pyruvate releases carbon dioxide to form acetaldehyde, and electron from NADH are transferred to acetaldehyde to produce ethanol anf NAD
ethanol fermentation equation
Glucose+2ADP+2Pi→2ethanol+2CO2+2ATP+2H2O
in both fermentation pathways:
NADH is oxidized to NAD
bread making involves ethanol fermentation and typically uses yeast, sugar, flour, and water. Why are yeast and sugar used?
Yeast cells are eukaryotes. In bread making, yeast can use sugar as a food source for ethanol fermentation. The carbon dioxide produced in the process causes the bread to rise. The ethanol is removed in the baking process
excess glucose is stored as ___________ in animals
glycogen
excess glucose is stored as ____________ in plants
starch
carbohydrate in your diet are digested to produce:
a variety of sugars
some are monosaccharides (fructose, mannose, and galactose) with one sugar unit
Others are disaccharides (maltose, lactose, and sucrose) with two sugar units
the disaccharides are hydrolyzed into monosaccharides, which are transported into cells
fatty acids and proteins
are a useful source of energy
oxidation of fatty acids:
produce large amount of ATP example: palmitic acid
When ATP levels are high
the cell has a high amount of free energy and is poised to carry out cellular respiration
When ATP levels are low
pathways that generate ATP are activated
level of ATP inside a cell can therefore be an indicator of:
of how much energy a cell has available
how does muscle tissue generate ATP during short term exercise?
muscle tissue generates ATP during short-term exercise by converting stored glycogen to glucose
Photosynthesis
energy and carbon are incorporated into carbohydrates
Calvin Cycle
a three step process that uses carbon dioxide to synthethize carbohydrates
Equation for photosynthesis
6CO2 + 6H2O ------> C6H12O6 + 6O2
photosynthesis is a redox reaction
Photosystems
absorption of light by protein pigment known as photosystem
photosystems use absorbed light energy to drive redox reaction
Where does O2 come from?
water, not carbon dioxide
in eukaryotes photosynthesis takes place in
chloroplasts
Note
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