Lecture Exam 3 Flashcards
diffusion (definition)
movement of molecules across a selective (semi-permeable) barrier from high concentration to low concentration
selective (semi-permeable) barrier (definition and example)
barrier that allows water molecules to pass thru, but not most of the molecules dissolved in the water
ex. plasma membrane
osmosis (definition)
diffusion of water molecules across a selective (semi-permeable) barrier from high concentration to low concentration
solutes
molecules that are dissolved in water
concentration of water is determined by:
concentration of solutes in the water
solute potential (psi s) (definition)
measure of the concentration of solutes dissolved in water
pure water has ___ solutes
psi s = ___
no solutes
psi s = 0
psi s = 0 (value and what it means for water)
highest value
water molecules are most concentrated
adding solutes ____ psi s
lowers
psi s < 0 (negative value)
as solute concentration increases, psi s ____ and water concentration _____
psi s decreases
water concentration decreases
water moves from areas of ____ psi s to areas of _____ psi s
areas of ___ water [ ] —> areas of ___ water [ ]
areas of ___ solute [ ] —> areas of ___ solute [ ]
areas of ___ solute potential —> areas of ___ solute potential
higher psi s –> lower psi s
higher water [ ] —> lower water [ ]
lower solute [ ] —> higher solute [ ]
higher solute potential —> lower solute potential
water will move until the psi s is ______ on both sides
equal on both sides
osmosis in cells
plasma membranes –
cells depend on the regulated movement of ___ ___ across the PM to ___ ___
osmosis is critical to survival of cells
plasma membranes – semi-permeable barriers
cells depend on the regulated movement of water molecules across the PM to stay alive
if psi s on inside and outside of cell are equal…
water is entering and leaving the cell in equal amounts
if psi s is higher outside of a cell than inside…
water will rush into cell
cell will swell
cell could burst (lysis)
psi s is higher outside cell
water [ ] higher outside cell
solute potential higher outside
solute [ ] higher inside cell
if psi s is higher inside of a cell the outside…
water will rush out of cell
cell will shrink
cell could dehydrate and die
psi s higher inside cell
water [ ] higher inside cell
solute potential higher inside cell
solute [ ] higher outside cell
medical application of osmosis in brain
blood brain barrier keeps most medicines from entering brain
lower psi s of blood (inject solute – Mannitol) –>
water moves out of capillary wall cells –>
capillary wall cells shrink slightly and create an opening b/n cells –>
medicine can pass into brain
energy (definition)
capacity to do work
2 forms of energy:
kinetic and potential
kinetic energy (definition and examples)
energy of motion, variety of forms:
- heat, light, mechanical
potential energy (definition and examples)
stored energy:
- concentration gradients, chemical bonds
thermodynamics (definition)
branch of chemistry that deals w/ energy transformations (changes)
can be boiled down to 2 main laws:
- 1st Law of Thermodynamics
- 2nd Law of Thermodynamics
1st Law of Thermodynamics
conservation law
energy cannot be created or destroyed
energy can only change from one form of energy to another
total amount of energy in universe remains constant
2nd Law of Thermodynamics
no energy transfer is 100% efficient
some energy is always lost (usually as heat) and becomes unusable energy
entropy
unusable energy
entropy in universe is continuously increasing
free energy (definition and what is happening to free energy in universe?)
usable energy
usable energy in universe is continuously decreasing
calculating Gibbs free energy (usable energy)
G = H - TS
G = free energy, energy available to do work H = enthalpy, total amount of energy in a molecule's chem bonds (TS) = amount of disorder in a molecule T = absolute temp S = entropy, unusable energy
change in free energy after chem reactions (reactants —> products)
chem reactions begin w/ the reactants (reactants have a certain amount of free energy)
chem reactions end w/ the products (products have a certain amount of free energy)
products will either have more or less free energy than the reactants
2 types of reactions
exergonic
endergonic
what determines the type of reaction?
change in free energy
-∆G
what type of reaction is this?
exergonic reaction
products have < free energy than reactants
energy is released, can be used to do work
rxn can be spontaneous – rxn has potential to occur on its own w/o extra energy input
+∆G
what type of reaction is this?
endergonic reaction
products have > free energy than reactants
energy is absorbed – input of energy is required
never spontaneous – rxn will not occur w/o energy input
graph of endergonic rxn
G of products > G of reactants
+∆G – energy is absorbed
endergonic rxns require energy input
graph of exergonic rxn
G of products < G of reactants
-∆G – energy is released
overall net release of energy
in cells (relationship b/n ender and exergonic rxns)
free energy released by exergonic rxns can be used to drive endergonic rxns forward
reaction coupling
exergonic and endergonic rxns are coupled together
energy to drive endergonic rxns comes from exergonic rxns
ATP (definition)
adenosine triphosphate
type of nucleic acid
energy currency of cell
energy storage molecule
ATP hydrolysis
exergonic rxn
reactants – (higher free energy) ATP and H2O
products – (lower free energy) ADP + other products
-∆G – energy is released. energy is used to power endergonic rxns in a cell
structure of ATP
adenosine triphosphate
adenine (nitrogenous base)
ribose (5-carbon sugar)
3 phosphate groups (negatively charged)
hydrolysis of ATP to ADP _____ energy
releases energy
ATP –> ADP – taking away one of the phosphate groups
AMP is lowest G state
exergonic ATP hydrolysis
G of reactants > G of products
-∆G: energy is released and can be used to power an endergonic rxn
reactants: ATP & H2O
products: ADP and other products
example of coupled reactions
hydrolysis of ATP is exergonic:
ATP + H2O –> ADP + Pi
-∆G
synthesis of glutamine is endergonic:
glutamate + NH4 –> glutamine
+∆G
coupling the rxns:
reactants: glutamate + NH4 + ATP + H2O
products: glutamine + ADP + Pi
net: exergonic
ATP cycle (know the diagram)
ATP hydrolysis:
ATP + H2O –> ADP + Pi
exergonic – releases energy –> becomes energy for endergonic cellular processes
ATP synthesis:
ADP + Pi –> ATP + H2O
endergonic – requires energy –> uses energy from exergonic cellular rxns
kinetics of a rxn
rate at which rxn occurs
thermodynamics of a rxn
refers to whether energy was released or absorbed
relationship b/n TD and kinetics of a rxn
TDs say nothing about the rates of rxns
what is rate of rxn dependent on?
activation energy – how much AE is required
activation energy (definition)
amount of G required to start a chem rxn
rxns w/ high AE have ___ rate of rxn
low
rxns w/ low AE have ___ rate of rxn
high
2 components of AE
collision energy of reactants
orientation of reactants during collisions
catalysts (mechanism)
lower AE and increase rate of rxn
enzymes
biological catalysts that can:
1) hold reactants in favorable orientations
2) stress the chem bonds of reactants
enzymes ___ AE of a rxn, which makes rxn occur at ___ rate
lower AE
faster rate
4 categories of organisms (relating to energy and carbon sources)
photoautotroph
chemoautotroph
photoheterotroph
chemoautotroph
photoautotroph (energy and carbon source, examples)
energy source - light
carbon source - CO2
ex. plants & some bacteria
chemoautotroph (energy and carbon source, examples)
energy source - chemicals
carbon source - CO2
ex. some bacteria
photoheterotroph (energy and carbon source, examples)
energy source - light
carbon source - organic
ex. some bacteria
chemoheterotrophs (energy and carbon source, examples)
energy source - chemicals
carbon source - organic
ex. animals
factors in ecosystem
abiotic – nonliving
biotic – living
examples of abiotic factors
light, temp, H2O, pressure, etc.
examples of biotic factors
producers, consumers, decomposers
how does energy flow thru an ecosystem?
energy flow:
sunlight –> producers –> consumers –> decomposers –> heat
energy from sun:
earth and living things are ___ ___
sun radiates ___ calories of energy/sec and only a ___ reaches earth
___ of energy that reaches earth is reflected by clouds and dust in atmosphere
less than ___ is absorbed by producers (plants)
earth and living things are open systems
sun radiates 10^26 calories of energy/sec & only a fraction reaches earth
50% of energy that reaches earth is reflected by clouds and dust in atmosphere
less than 1% is absorbed by producers (plants)
trophic (definition)
refers to food or nourishment
trophic level (definition)
describes where an organism is in the food chain (or food web)
energy flow thru a food chain begins w/ ___
producers
producers occupy ___ trophic level
1st trophic level
consumers occupy ___ trophic levels
the remaining trophic levels (2nd and above)
energy flow thru trophic levels (1-4) – (types of organisms)
producers –> primary consumers (herbivores) –> secondary consumers (carnivores) –> tertiary consumers (top carnivores)
decomposers (bacteria, detritivores, fungi)
energy transfer b/n trophic levels is very ___
inefficient
efficiency of energy transfer b/n trophic levels is about (amount)
~10% (90% energy loss)
how is energy lost between tropic levels?
1) some energy is lost in feces - inefficient energy absorption during digestion
2) some energy is lost bc it can’t be extracted
energy in: cellulose, hair, claws, feather, etc.
3) some energy is lost “staying alive”:
moving, metabolizing, breathing, lost as heat
ex. beef cattle (eat plants for energy)
62% of energy taken in by the cow is lost
- either isn’t extracted by the cow (lost in feces)
- or is locked up in indigestible structures like hooves, horns, etc.
34% of energy is used living and “staying alive”
only 4% of the energy cow consume will be available to next trophic level (96% loss)
energy transfer b/n trophic levels is very inefficient… (affect on # of trophic levels)
limits the # of trophic levels that can be supported
energy transfers b/n trophic levels (start out w/ 1000 calories in 1st trophic level)
1000 calories produced by photosynthesis at 1st trophic level
100 calories are transferred to the 2nd trophic level
10 calories transferred to the 3rd trophic level
1 calorie transferred to the 4th trophic level
primary components of organisms
6 primary atoms:
CHONPS
carbon hydrogen oxygen nitrogen phosphorus sulfur
all macromolecules of lipids, carbs, DNA, RNA, and proteins have…
CHO
elemental building blocks of lipids
CHOP
lemon pie
elemental building blocks contained in carbohydrates
CHO
elemental building blocks contained in DNA/RNA
CHOPN
dippin pine nuts
elemental building blocks contained in proteins
CHONS
party never stops
can energy be recycled?
no; it only changes forms; eventually all energy is lost as heat
can matter be recycled?
yes
limited amount of CHONPS on Earth
each element cycles into and out of living systems in different ways
element’s reservoir (definition)
where element is when not part of organism
cycling of CHONPS
elements cycle b/n reservoirs and organisms
incorporation: reservoir of element –> organisms return: organisms –> reservoir
(remember diagram)
primary reservoir (PR) for Carbon
CO2 in atmosphere
primary reservoir (PR) for Nitrogen
N2 in atmosphere
primary reservoir (PR) for Oxygen
H2O molecules
primary reservoir (PR) for Hydrogen
H2O molecules
primary reservoir (PR) for Phosphorus
soil and ocean beds
primary reservoir (PR) for Sulfur
soil and ocean beds
some common reservoirs
water, atmosphere, sediment
cycling of CHO connects ___ & ___
photosynthesis and cellular respiration
remember diagram
nitrogen is needed for what type of macromolecules?
proteins and nucleic acids
___% of air is N2
80%
why is atmospheric N2 not usable by most organisms?
N2 is very inert, unreactive
nitrogen enters into ecosystems thru ___
nitrogen fixation
nitrogen fixation (general description)
nitrogen goes from its reservoir in atmosphere and enters ecosystems thru nitrogen fixation
nitrogen-fixing bacteria (NFB) do what?
convert unusable inert N2 into reactive, usable ammonia (NH3) and nitrate (NO3-)
(remember diagram)
where do NFB live?
soil & on roots of some plants
nitrogen recycling (mechanism)
1) plants incorporate the NH3 (ammonia) and NO3- (nitrate) into macromolecules (MMs)
2) N-containing MMs are taken up by consumers and taken up by decomposers
3) decomposers in soil convert the nitrogen in MMs back into NH3 (ammonia) and NO3- (nitrate) –> (soil)
(remember diagram)
nitrogen fixation provides ___% of the N needed for living things
~5%
nitrogen recycling provides ___% of the N needed for living things
~95%
denitrification (definition and what carries it out)
process where N is retuned to the air as N2
carried out by bacteria
nitrogen fixation in agriculture:
global crop production is supported by ___-___ ___ (made by industrial nitrogen fixation)
production of N-containing fertilizers has ___ the natural rate of nitrogen fixation
___ of the world’s energy supply is used to fix nitrogen for use in fertilizers
global crop production is supported by nitrogen-containing fertilizers (made by industrial nitrogen fixation)
production of N-containing fertilizers has doubled the natural rate of nitrogen fixation
1-2% of the world’s energy supply is used to fix nitrogen for use in fertilizers
phosphorus is important for (macromolecules)
nucleotides (ATP)
nucleic acid polymers (RNA/DNA)
phospholipids (plasma membranes)
phosphorus cycle (steps)
plants incorporate P from sediment
animals eat plants
plants/animals die and decomposers return P to sediment
plants incorporate it again and the cycle begins again
sulfur is important for (macromolecules, critical for ___ ___)
found in certain amino acids (proteins)
critical for protein folding
sulfur cycle (steps)
plants incorporate S from sediment
animals eat plants
plants/animals die and decomposers return S to the sediment
plants incorporate it again and the cycle begins again
reduction/oxidation (redox) reactions occur when…
molecules gain or lose electrons
oxidation is ___ of electrons
loss
reduction is ___ of electrons
gain
redox reactions are coupled
as molecules gain electrons – are reduced
other molecules must lose electrons – be oxidized
electrons taken from oxidized molecules are transferred to reduce other molecules
importance of redox rxns
chains of redox rxns results in a flow of electrons called an electron transport chain
electron transport chain (definition)
chain of redox rxns that results in a “flow” of electrons
electron carriers (definition)
molecules and enzymes that make up the ETC
electron carriers (function)
accept electrons (become reduced) and donate electrons (become oxidized)
affinity of electron carriers (ECs) for electrons
different ECs have different affinities for electrons
first EC in ETC has lowest electron affinity
each EC in the ETC has increasingly more affinity for electrons
last EC in an ETC has the most electron affinity
ECs and ETC are critical to photosynthesis and cellular respiration
photosynthesis (chemical equation)
sunlight + CO2 + H20 –> glucose (sugar) + O2
photosynthesis (general terms)
light energy powers the production of glucose (energy is transferred)
efficiency of energy transfer in photosynthesis
30%;
30% of photon energy ends up stored as chemical energy (glucose)
site of photosynthesis
division of labor in chloroplasts
thylakoid membranes contain the pigments (chlorophylls) that capture light energy
stroma: where glucose is made
2 parts to photosynthesis
light reactions (light dependent rxns)
dark reactions (light independent rxns – doesn’t occur at night) AKA Calvin Benson cycle
light reactions occur at the ___ ___
thylakoid membrane
light reactions require:
light as an energy source
H2O as an electron source
light reactions produce:
ATP as an energy storage molecule
NADPH as an electron carrier (reduced form)
O2 as a byproduct
dark reactions occur in the ___
stroma
dark reactions require:
CO2 as a carbon source
ATP (from light rxns) as an energy source
NADPH (from light rxns) as an electron source
dark reactions produce:
glucose (energy storage molecule – C6H12O6)
ADP + Pi (from ATP hydrolysis)
NADP+ (from oxidation of NADPH)
pigment molecules (like chlorophylls) are critical to the light reactions bc they _____
capture light energy
chlorophylls are contained w/in structures called ___
photosystems
photosystems are located in ___
thylakoid membranes
photon energy is captured by ___ contained in ___
chlorophylls contained in photosystems
photon capture (mechanism)
antenna chlorophylls (AC) capture photon energy
photon energy radiated from AC to AC
energy captured by the reaction center chlorophyll (RCC)
energy is absorbed by electrons in the RCC
energized electrons are:
1) ejected from RCC
2) captured by an electron carrier
3) enter into an electron transport chain
ejected electrons are replaced
where are the photosystems located?
thylakoid membrane
PS2 gets replacement electrons from ___
H20
PS1 gets its electrons from ___
PS2
in both PS1 and PS2, antenna chlorophyll ___
capture light energy
in both PS1 and PS2, photon energy is used to ___ w/in
energy electrons w/in reaction center chlorophylls (RCC)
in PS2, energized electrons enter the ___ and are transported from ___
electron transport chain and are transported from PS2 to PS1
in PS2, energy from the electrons in ETC is used to ___
produce ATP
in PS2, ___ is used to produce ATP
energy from the electrons in ETC
in PS2, replacement electrons come from ___
H2O
in PS2, ___ enter the ETC and are transported from PS2 to PS1
energized electrons
in PS2, ___ come from H2O
replacement electrons
in PS1, replacement electrons come from ___
PS2
in PS1, ___ come from PS2
replacement electrons
in PS1, de-energized electrons from PS2 are ___
re-energized w/ photon energy
in PS1, ___ from PS2 are re-energized w/ photon energy
de-energized electrons
in PS1, energized electrons are transferred to ___, thereby ___ to ___
NADP+
thereby reducing it to
NADPH
in PS1, ___ are transferred to NADP+, thereby reducing it to NADPH
energized electrons
detritivore (definition)
an animal which feeds on dead organic material, especially plant detritus (plant waste)
