An adenine-containing nucleoside triphosphate that releases free energy
when its phosphate bonds are hydrolyzed. This energy is used to drive
endergonic reactions in cells.
The movement of a substance across a cell membrane, with an expenditure
of energy, against its concentration or electrochemical gradient;
mediated by specific transport proteins.
Having both a hydrophilic region and a hydrophobic region.
An adenine-containing nucleoside triphosphate that releases free energy
when its phosphate bonds are hydrolyzed. This energy is used to drive
endergonic reactions in cells.
Membranes have been chemically analyzed and found to be made of?
Made of Proteins and Lipids
Effects of Cholesterol on membranes fluidity at warm temperatures, (such as 37 C)
restrains movement of phospholipids at warm temps
Effects of Cholesterol on membranes fluidity at COOL temperatures
maintains membrane fluidity by preventing tight packing
Integral proteins that span the membrane
They hydrophobic regions of an integral protein consist of one or more stretches of
nonpolar amino acids, often coild into alpha helices
Six major functions of membrane proteins?
- Enzymatic activity
- Signal transduction
- Cell-cell recognition
- Intercellular joining
- Attachment to the cytoskeleton and extra cellular matrix (ECM)
cells recognize eachother by _______,often carbohydrates, on the plasma membrane.
binding to to surface molecules
The asymmetrical distribution of proteins, lipids, and associated carbohydrates in the plasma membrane is determined when__________.
the membrane is built by the ER (synthesis of proteins lipids and carbs (glycoproteins) and Golgi apparatus (glycolipids formation from modifiying carbs)
The permeability of the LIpid Bilayer involves ________, such as hydrocarbons, which can dissolve in the lipid bilayer and pass through the membrane rapidly, and _________, such as sugars, that do not cross the membrane easily.
Hydrophobic (nonpolar) molecules AND Polar molecules
Transport Proteins allow passage of _______ substances across the membrane and are______for the substance it moves.
- hydrophillic substances
2 types of transport proteins and function
- aquaporins--facilitate the passage of water only
- carrier proteins--bind to molecules and change shape to shuttle across membrane
diffusion of a substance across a membrane with no energy investment
(down the concentration gradient)
ie diffusion, facilitated diffusion, osmosis
The control of water balance in cells without walls
Channel proteins include
- Aquaporins, facilitated diffusion of water
- ion channels, open and close in response to a stimulus (gated channels)
The kidney disease Cystinuria is caused by
malfunctions in specific transport systems
Sodium Potassium Pump steps of Na and K
3 Na+ out for every 2 K+ in
- 1. Na+ binds to pump, affinity for Na high
- 2. Phosphorylation of protein by ATP
- 3. Protein shape change, Na expelled, Affinity for Na low
- 4. Affinity high for K, which binds and triggers release of phosphate inside cell
- 5. loss of phosphate restores proteins shape, affinity Low for K
- 6. K released, affinity high for Na again
the major electrogenic pump for ANIMAL cells
Main electrogenic pump of PLANTS, fungi, and bacteria
moves substances against conconetrations gradiant, requires energy ATP, performed by specific protens embedded in membranes, allows cells to maintain concentration gradients that differ from their surroundings
Large molecules such as polysaccs and proteins cross the membrane in bulk via ________, which requires________.
vesicles AND energy
Three types of endocytosis
- Phagocytosis--engulfs a particle in a vacuole, lysosome digests particle
- pinocytosis- molecules gulped into tiny vesicles
- receptor-mediated endocystosis- binding of ligands to receptors triggers viscle formation
- (ligands are any molecules that bind to a receptor site of another molecule)
a miniature chemical factory where thousands o reactions occur. It also extracts energy and applies energy to perform work.
where some organisms convert energy to light
the totality of an organisms's chemical reactions and an emergent property of life that arises from interactions between molecules within the cell
begins with a specific molecule and ends with a product and each step is catalyzed by a specific enzyme
pathway that releases energy by breaking down complex molecules into simpler compounds ie hydrolysis, cellular respiration (exergonic)
this pathway consumes energy to build complex molectules from simpler ones
ie the synthesis of protein from amino acids, dehydration (endergonic reaction-stores energy)
the capacity to cause change, it exists in various from some of which can peform work; can also be converted from one form to another
energy associated with motion
kinetic energy associated with random movements of atoms or molecules
heat (thermal energy)
energy that matter possesses because of its location or structure
potential energy available for release in a chemical reaction
the study of energy transformations
As related to thermodynamics, organisms are _______ where energy and matter can be transferred between the system and its surroundings.
first law of thermodynamics
- also called the "principle of conservation of energy"
- Energy can be transferred and transformed, but it can neither be created or destroyed
Second law of thermodynamics states
Every energy transfer or transformation increases the entropy (disorder) of the universe
During every energy transfer or transformation, some energy is unusable, an is often lost as
Living cells unavoidably convert organized froms of energy to
occurs without energy input; they can happen quickly or slowly
For a process to occur without energy input, it must increase the
entropy of the universe
Less ordered materials are made into ordered structures by
Organisms also replace ordered froms of ______ and _______ with less ordered forms.
matter and energy
Energy flows into an ecosystem in the form of _____ and exits in the form of _______.
light ; heat
The evolution of more complex organsims does not violate the ____ of thermodynamics.
Entropy (disorder) may _____ in an organism, but the universe's total entropy ______ .
decrease ; increases
A living system's energy that can do work when temperature and pressure are uniform, as in a living cell
Free energy change =
- Change in total energy (^H) MINUS Temperature in Kelvin (T) TIMES change in entropy (^S)
- (^G) = (^H) - (T)(^S)
Only processes with a ______ are spontaneous.
negative change in free energy (-^G)
a measure of a system's instability, its tendency to change to a more stable state
During a _______, free energy increases and the stability of a system increases
a state of maximum stability is called
Work can only be peformed by a spontaneous process when it is
moving towards equilibrium
Relating to free energy and metabolism, what proceeds with a net release of free energy and is spontaneous?
Relating to free energy and metabolism, what absorbs free energy from its surroundings and is NOT spontaneous?
this powers cellular work by coupling exeronic reactions to endergonic reactions
a cell does three main kinds of work
Chemical, Transport, and Mechanical
cells manage energy resources by ________, or the use of an exergonic proces to drive an endergonic one.
Most energy coupling in cells is mediated by
ATP is the cells enegy shuttle and composed of
a ribose (a sugar), adenine (nitrogenous base), and three phosphate groups
The bonds between the phosphate groups of ATP's tail can be broken by
Energy is released from ATP when the______________. This release of energy comes from the _____ change to a state of lower free energy, not from the phosphate bonds themsevles.
terminal bond is broken; chemical change
Three types of cellular work (mechanical, transport, and chemical) are powered by
the hydrolysis of ATP
In the cell, the energy from the exergonic reaction of ATP hydrolysis can be used to drive an
coupled reactions are
ATP drives endergonic reactions by _________ , transferring a phosphate group to som other molecule, such as a reactant, which makes that recipient molecule phosphorylated.
ATP is a renewable resource that is regenerated by addition of a ______group to ________________.
phosphate group; ADP
The energy to phosphorylate ADP comes from ___________in the cell.
temporarily stored in ATP and drives most cellular work
chemical potential energy
a chemical agent that speeds up a reaction WITHOUT being consumed by the reaction
a catalytic protein
Hydrolysis of sucrose by the enzyme sucrase is an example of
an enzyme-catalyzed reaction
The initial energy needed to start a chemical reaction is called the
free energy of activation or activation energy (EA), which is often supplied in the form of HEAT from the surroundings
Enzymes catalyze reactions by
lowering the EA barrier
Enzymes do not affect the________________; instead, they hasten reactions that would occur eventually
change in free energy (^G)
The reactant that an enzyme acts on is called
the enzymes SUBSTRATE
The enzyme binds to its substrate, forming an
the region on the enzyme where the substrate binds
_______ of a substrate brings chemical groups of the active site into positions that enhance their ability to catalyze the reaction.
The active site can lower an EA barrier by
- Covalently bonding to the substrate
- Orienting substrates correctly
- Providing a favorable microenvironment
- Straining substrate bonds
non protein enzyme helpers that may be inorganic (such as a metal in ionic form) or organic
Cofactors (these conenzymes include vitamins)
bind to the active site of an enzyme, competing with the substrate
bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective
examples of enzyme inhibitors
toxins, poisons, pesticides, and antibiotics
this may either inhibit or stimulate an enzymes activity; it occurs when a regulatory molecule binds to a protein at one site and affects the protein's function at another site.
in allosteric activation and inhibition the binding of an activator stabilizes the________ form of the enzyme, while the binding of an inhibitor stabilizes the_______form of the enzyme.
a form of allosteric regulation that can amplify enzyme activity; binding by a substrate to one active site stabilizes favorable conformational changes at all other subunits.
Allosteric regulators are attractive drug candidates for enzyme regulation. Inhibition of _______ enzymes called caspases my help management of inappropriate inflammatory responses.
In__________,the end product of a metabolic pathway SHUTS DOWN the pathway
feedback inhibition (most pathways)
prevents a cell from wasting chemical resources by synhesizing more product that is needed
feedback inhibition (most pathways)
Some enzymes act as structural components of ________. In eukaryotic cells, some enzymes reside in specific organelles; ie, enzymes for_________ are located in mitochondria.
- cellular respiration
partial degradation of sugars that ocurs without O2
Consumes organic molecules and O2 and yelds ATP
consumes compouds other than 02
includes both aerobic and anaerobic respiration but is often used to refer to aerobic respiration
cellular respiration equation
C6H12O6 + 6 O2----->6 CO2 + 6 H20 + energy (~38 ATP and heat)
The transfer of _____ during chemical reactions releases energy stored in organic molecules
chemical reactions that transfer electrons between reactants are called
oxidation-reduction reactions, or redox reactions
when a substance loses electrons it becomes
oxidized as in the process of oxidation
when a substance gains electrons it becomes
- reduced as in the process of reduction (the amount of positive charge is reduced)
The electron donor is called the
the electron acceptor is called
the oxidizing agent
What is reduced and what is oxidized during cellular respiration? What does reduced and oxidized mean?
The glucose (C6H12O6) is oxidized (gains charge by losing electrons) and the oxygen (O2) is reduced loses charge by gaining electrons)
This coenzyme and electron acceptor functions as an oxidizing agent during cellular respiration
represents stored energy that is tapped to synthesize ATP, also passes the electrons to the electron transport chain.
NADH (reduced form of NAD+)
passes electrons in a series of steps instead of one explosive reaction
electron transport chain
pulls electrons down the electron transport chain in an energy yielding tumble and the energy yielded is used to regenerate ATP
summarize the 3 stages of cellular respiration
- 1. Glycolysis--breaks down glucose into two molecules of pyruvate (occurs in cyctosol)
- 2. Citric Acid cycle--completes the break down of glucose in mitochondrial matrix of eukaryotes
- 3. Oxidative phosphorylation--accounts for most of the ATP synthesis ~90% (powered by redox reactions)
A smaller amount of ATP (~10%) is formed in glycolysis and the citric acid cycle by a mechanism called
Energy investment phase "Priming Phases" of glycolysis 5 steps
Regulatory step 1
end of 5 steps end up with two different molecules
1.Glucose enters the cell, phosphorylated by hexokinase (stored in muscles while glucokinase stored in liver) Results in the use of 1 ATP hydrolzyed to ADP making glucose-6-phosphate
- 3. 1 ATP hydrolyzed to ADP= 2 Total ATP's invested!!!
- 5. At the end result is DHAP gets converted to 2 Glyceral 3 phosphates (GAP) 2 three carbon molecules!! which gets thrown into the next phase "PAY OFF" phase.
1 molecule of NADH gets converted into
3 molecules ATP
1 FADH2 gets converted into
2 molecules ATP
Energy Payoff phase (energy liberation stage) step 6-10
- 6. 2 NAD+ --> 2 NADH (2*3= 6 ATP)
- 7. 2 ADP----> 2 ATP
- 10. 2 ADP---> 2 ATP AND PYRUVATE KINASE >>>2 PYRUVATE
Before the Citric acid cycle can begin, Pyruvate must be converted to acetyle CoA, which links the cycle to Glycolysis. Three steps invovled are:
- 1. Co2 is released
- 2. Last 2 Carbon's oxidized, NAD+ to NADH (stored energy)
- 3. Coenzyme A (CoA) ----> added to to 2 Carbon Pyruvate to create acetyle CoA--high potential energy ready for Citric Acid cycle
Citric acid cycle (krebs) oxidizes organic fuel from pyruvate, generating:
1 ATP, 3 NADH, and 1 FADH2 per turn (must go through twice to double since glycolysis produces 2 pyruvate)
Citric (Kreb's) cycle
How many ATP?
1. 2 carbon acetyl group of acetyl CoA
joins the cycle by combining with oxaloacetate
(4 carbon molecule), forming a Citrate
- Loss of CO2 Isocitrate is oxidized, reducing NAD+ to
- 4. NADH,
- Loss of CO2
- 5. 1 ATP produced from succinyl CoA converting to succinate
- 6. FADH2 produced
- 8. NADH and regeneration of oxaloacetate
- 24 ATP produced
- + 8 ATP Glycolysis
Following the glycolysis and the citric acid cycle, ____ and ______ account for most of the energy extracted from food.
NADH and FADH2
These two electron carriers donate electrons to the electron transport chain, which powers ATP synthesis via oxidative phosphorylation
NADH and FADH2
the electron transport chain is in the
cristae of the mitochondrion
Most of the____ ____ ___ components are proteins, which exist in multi protein complexes. Some of the electrons are passed through a number of proteins including________(each with an iron atom) to O2
- Electron Transport chain
Electrons drop in free energy as they go down the chain and are finally passed to O2, forming__1___. Electrons are transferred from__2__or__3____ to the electron transport chain. The electron transport chain DOES NOT generate___4_.
- 1. H2O
- 2. NADH
- 3. FADH2
- 4. ATP
function is to break the large free-energy drop from food to O2 into smaller steps that release energy in manageable amounts.
electron transport chain
_________ in the electron transport chain causes proteins to pump H+ (protons) from the mitochondrial matrix to the intermembrane space. H+ (protons) then move back across the membrane passing through channels in_______, which uses the exergonic flow of H+ to drive phosphorylation of _ _ _.
- electron transfer
- ATP synthase
the use of energy in a H+ gradient to drive cellular work
The H+ (proton) gradient is referred to as a________, emphasizing its capacity to do work.
The energy-coupling mechanism that couples the redox reactions of the electron transport chain to ATP synthesis
Oxidative Phosphorylation involves
1. Electron Transport Chain--electron transport and pumping of protons (H+) which create an H+ gradient across the membrane.
2. Chemiosmosis--ATP synthesis powered by the flow of H+ back across the membrane
During cellular respiration, most energy flows in this sequence
Glucose-->NADH-->Electron transport chain-->Proton motive force-->ATP
About ____% of the energy in a glucose molecule is transferred to ATP during cellular respiration, making about___ATP
Most cellular respiration requires____to produce ATP
Glycolysis can produce ATP _____ or _______ ___ (in aerobic and anaerobic conditions)
with or without O2
In the absence of O2, __________ couples with fermentation or _________ ______ to produce ATP.
- anaerobic respiration
uses an electron transport chain wth an electron acceptor other than O2 ie sulfate
uses phosphorylation instead of an electron transport chain to generate ATP
Fermentation consists of glycolysis plus reaction that regenerate_____, which can be reused by glycolysis.
Two types of fermentation are
- Alcohol fermentation---1. generate/release CO2
- 2. pyruvate is converted to ethanol
Lactic acid fermentation---pyruvate is reduced to NADH
, forming lactate as an end product from pyruvate NO CO2 release
Fermentation VS Aerobic Cellular Respiration
- -Both use glycolysis to oxidize glucose etc to pyruvate
- -Different Final electron acceptors: Fermentation uses organic molecules (like pyruvate or acetaldehyde)
- Respiratin uses O2
- -Cellular respiration produces 38 ATP per glucose, while Fermentation produces 2 ATP per glucose
carry out fermentation or anaerobic respiration and cannot survive in the presence of O2
Yeast and many bacteria can survive using either fermentation or cellular resiration because they are_____. ______ is a fork(decision is made) in the metabolic road that leads to two altenative catabolic routes.
- facultative anaerobes
Fatty acids are broken down by_______ to generate acetyle CoA > citric acid cycle > oxidative phosphorylation
Sequence to produce ATP
Proteins > 1 ( ) > 2 > 3 > 4 > 5
Amino acids (deamination, NH3 biproduct) >
- Amino goups >
- Glycolysis or citric acid cycle >
- Ox Phos > ATP
Sequence of fats to ATP
- Fats to (glyceral) and (fatty acids)
- / /
- Glycolysis------GA-3-P /
- \ / /
- \--------- Pruvate /
- / /
- acetyl CoA <----/
- Citric Acid cycle > Oxidative Phosphorylation > ATP
If ATP concentration begins to drop,__________; when there is plenty of ATP, _________.
- respiration speeds up
- respiration slows down (inhibition)
respiration to speed up
During feedback inhibition, having enough citrate means you have enough ATP which means
Inhibition of respiration
Autotrophs sustain themsevles and dont' eat anything derived from other organsisms are called_______
heterotrophs obtain their organic material from other organsms and are called _______
Almost all plants are ________, using the enegy of sunlight to make organic molecules from _____ and _____.
- H20 and CO2
Chloroplasts are structurally similar to and likely evolved from_____ ______. This is the site where ________occurs.
- photosynthetic bacteria
CO2 enters and O2 exits the leaf through microscopic pores called
chloroplasts are found mainly in cells of the ______, the interior tissue of the leaf
The typical mesophyll has how many chloroplasts?
chlorophyll is in the____ of _____ (connected sacs in the chloroplast). They may be stacke in columns called?
- membranes of thylakoids
Chloroplasts also contain_____, a dense fluid (inside inner membrane)
6 CO2 + 6 H2O+ light energy---->C6H12O6 + 6 O2
Chloroplasts split H2O into hydrogen and oxygen, incorporating the _____ of hydrogen into ______ _____.
Photosynthesis is a redox process in which ______ is oxidized and _____ is reduced.
H2O is oxidized (loses electrons making it more charged) and CO2 is reduced (gaining electrons but losing charge)
Two stages of Photosynthesis
The light reactions (the photo part) and Calvin cycle (the synthesis part)
The Light reactions in the ________, split _____, release___, reduce____ to _____ and then generate ____ from ____ by _________ or (___________).
The Calvin cycle begins with _____, incorporating _____ into organic molecules.
It happens in the________, where it forms______from ______, using ____ and _______.
- Split H2O
- Release 02
- Reduce NADP+ to NADPH
- Generate ATP from ADP by photophosphoylation (chemiosmosis)
- Begins wth CARBON FIXATION incorporating CO2 into organic molecules
- Happens in the STROMA forms SUGAR from CO2 using ATP and NADPH
Chloroplasts are solar-powered chemical factories that contain _____structures, which transform light energy into the chemcical energy of ____ and _____.
Light is a form of ________energy, also called ________ radiation. This light travels in ____.
- rythmic waves
Wavelength is the distance between. Wavelength determines the type of ______ ____.
- crests of waves
- electronmagnetic energy
The________ _______ is the entire range of electromagnetic energy, or radiation.
Visible light consists of _________ (including those that drive photosynthesis) that produce colers we can see.
Light asl behaves as though it consists of desgrete particles, called
substances that absorb visible light.
Different _______ absorb different wavelengths. Wavelengths that are not absorbed are ____ or ______.
- reflected or transmitted
measures a pigments ability to absorb vairous wavelengths. Sends light through pigments and measures the fraction of light transmitted at each wavelength
a graph plotting a pigments light absorption versus wavelength
the absoption spectrum of chlorophyll a suggests that ____ and ____ light work best for photosynthesis
violet-blue and red
profiles the relative effectiveness of different wavelengths of radiation in driving a process
the main photosynthetic pigment
Accessory pigments, such as _____ broaden the spectrum used for photosynthesis
Accessory pigments called _______ absorb excessive light that would damage chlorophyll
- chlorophyll b
- carotenoids (carotene)
When a pigment absorbs light, it goes from a _______ to an_______, which is unstable
ground to excited state
When excited electrons fall back to the ground state, _______ are given off, an after glow called _______.
If illuminated, an isolated solution of chlorophyll will____, giving off ___ and ____.
fluoresce, light and heat
consists of a reaction-center complex ( a type of protein complex) surrounded by light harvesting complexes.
The light harvesting complexes which are ____ molecules bound to _____, funnel energy of photons to the reaction center
pigment molecules bound to proteins
A primary electron acceptor in the reaction center accepts an excited electron from __________This solar powered transfer of an electron from a _______ molecule to the primary electron acceptor is the first step of the light reactions.
two types of photosystems in the thylakoid membrane are
- Photosystem II (PSII) functions first!
- best at absorbing wavelengths of 680 nm
- Photosystem I (PSI) best at asborbing a wavelength of 700 nm
- -The reaction center of chlorophyll 'a' of PSI is called P700
During the light reactions, there are two possible routes for electron flow
cyclic and linear
Linear electron flow
- Primary pathway
- Involves both photosystems and produces ATP and NADPH using light energy
- Releases O2
- Electrons "fall" down an ETC from the primary electron acceptor of PSII to PSI releasing energy
cyclic electron flow
- uses only photosystem I
- produces ATP but not NADPH
Chloroplasts AND mitochondria generate_____ by chemiosmosis, but use different sources of energy.
Chloroplasts transfrom light energy into the ____ energy of___, while the Mitochondria transfer _____energy from food to ____
- CHEMICAL energy of ATP
- CHEMICAL energy from food to ATP
In chloroplasts, protons are pumped into the thylakoid space and drive ____ ___ as they diffuse back into the stroma
____ and ____ are produced on the side facing the stroma where the calvin cycle takes place.
ATP and NADPH
light reactions generate ___ and increase the potential energy of electrons by moving them from ____ to _____.
3 phases to Calvin cycle
how many turns?
- 1. Carbon fixation (catalyzed by rubisco) regulatory step
- 3 carbons come in
- 2. Reduction- sugar formed (G3P)
- 3. Regeneration of CO2 acceptor (RuBP)
Alternative mechanisms of carbon fixation in hot arid climates
- stomata closes, conserving H2O
- limiting photosynthesis
- reducing access to CO2 causing O2 build up
- (process called photorespiration) catch 22
consumes O2, releases CO2 without producing ATP or sugar
An external signal where proteins released be certain cells stimulate other cells to divide
stimulates the division of human fibroblast cells in culture
platelet-derived growth factor (PDGF)
an external signal in which crowded cells stop dividing
density-dependent inhibition (contact inhibition)
(cancer cells do not exhibit this)
Most cells exhibit______ _________, in which they must be attached to a substratum in order to divide
(cancer do not exhibit this)
formation of blood vessels
A normal cell is converted to a cancerous cell by a process called
If abnormal cells remain at the orginal site, the lump is called a_________. When the ab cells invade surrounding tissues and metastasize forming secondary tumors they are called________.
Tumor suppressor genes
protect or suppress cancer "tumors" off =cancer
- 1. P53--most important
3 types of genes
- 1. tumor suppressor genes- protect or suppress cancer
- 2. proto-oncogenes "good genes" want turned on!
- 3. oncogenes "bad genes" ON=CANCER! want off!