Studied by 10 people
bioenergetics
study of energy in living systems (environments) and the organisms (plants and animals) that utilize them
metabolism
the sum of all chemical reactions in a living organism. includes: cellular respiration and photosynthesis
enzyme
proteins that catalyze chemical reactions in living thing
characteristics of enzymes
needed for all chemical reactions (metabolism)
assists in breaking down and building biomolecules
most are proteins (end in ase)
aren’t used up in reactions; continue to work reactions until they are stopped
function depends on structure
only certain molecules can bind to enzymes
save cellular energy
parts of an enzyme
substrate
active site
enzyme substrate complex
allosteric site
substrate
specific reactant (molecule) that enzymes act on
active sites
place where substrate bind to enzymes
enzyme-substrate complex
when enzyme and substrate join together; induced fit between enzyme and substrate to catalyze reaction
allosteric site
site on enzyme that allows a molecule to start or stop reactions (on/off switch); save cellular energy
causes of enzyme denaturing
change in pH
change in temperature
change in salt balance
what is homeostasis for humans?
pH=7.4
temp=98.6
salt balance= 33ppm
what is non-competitive inhibition?
molecule that binds to allosteric site and causes shape change so the substrate can’t bind with the active site
what is competitive inhibition?
substrates that interfere with active sites so substrates can’t interact with enzymes.
what is allosteric regulation?
regulatory molecules that cause conformational shape changes to enzymes
2 types: inhibitors and activators
inhibitors
molecules that keep enzymes inactive; saves energy if enough product has been made
activators
molecules that keep enzymes active; saves energy because it keeps enzymes producing
what is the “lock and key” fit?
active sites work like a lock and key. a substrate must be a certain shape in order to fit with the enzyme. once an active site causes a conformational shape change the enzyme will catalyze the reaction.
catalysis
enzymes; substance that speed up chemical reactions by decreasing activation energy
characteristics that make enzymes catalysis
increase reaction rate
aren’t consumes with reaction
active site lower activation energy by creating a favorable environments for substrate
decrease activation energy
how are enzymes named?
named for the reaction they catalyze; end in “ase” if protein
amylase
lactase
maltase
sucrase
lipases
what organisms undergo photosynthesis?
autotrophs
autotroph
self-feeder; makes energy from sunlight (chlorophyll). includes all plants, phytoplankton, algae, mosses, and ferns.
formula for photosynthesis
6CO2 + 6H2O → C6H12O6 + 6O2
formula for cellular respiration
C6H12O6 → 6CO2 + 6H2O + energy
ATP
main energy molecule made during photosynthesis and respiration
how is ATP made?
hydrolysis breaks down ADP causing the covalent bond to break between phosphates which releases large amounts of energy
phosphorylation
when ATP gives a phosphate to another molecule (enzyme) so it can be activated. energy is released by breaking the covalent bond between phosphates
how can the rate of photosynthesis be found in a lab?
amount of CO2 present
amount of sunlight
amount of sugar made
amount of oxygen produced
how can the rate of cellular respiration be measured in a lab?
amount of CO2 present
amount of sugar present
amount of oxygen comsumed
photons
the energy wavelengths sunlight travels in
what photons are used in photosynthesis?
red (longest wavelenth, least energy) wavelengths and blue (shortest wavelength, most energy) wavelengths
green light is reflected
what does ROY G BIV stand for?
Red, Orange, Yellow, Green, Blue, Indigo, Violet
absorbed colors are used, reflected colors are not
chlorophyll A
main green pigment in plants; absorbs red light and had magnesium
chlorophyll B
green pigment helps chlorophyll A receive sunlight energy; mainly absorbs blue light
carotenoids
accessory pigments that help chlorophyll and proteins in thylakoid membrane
photosystem
a complex protein made of chlorophylls and proteins in thylakoid membrane
photosystem II
photosystem I
PSII
makes ATP and NADPH
PSI
only makes ATP
parts of a chloroplast
thylakoid
grana
lamella
stroma
calvin cycle
thylakoid
single disks that contain chlorophyll; photosystems II and I on thylakoid membrane trap sunlight; where light dependent reaction occur
grana
stack of thylakoids; increases surface area for photosynthesis
lamella
connection between grana
stroma
liquid between grana; where carbohydrates are made in calvin cycle
calvin cycle
occurs in stroma; uses ATP and NADPH from light reactions to make sugar
what is the goal of light reactions?
to make energy molecules that are passed on to the calvin cycle.
uses light to break water into O2 and H+. light excites the electrons released by water that travel through an electron transport chain to become ATP and NADPH (used in calvin cycle)
what is the goal of the calvin cycle?
to make sugar and carbon fixation.
light is not needed; uses the energy molecules made in the light reactions combined with CO2 to make sugar
what two process make up the light reactions?
non-cyclic electron flow
cyclic electron flow
non-cyclic electron flow
makes ATP and NADPH; starts and ends in different places (starts: PSII; ends: PSI)
cyclic electron flow
makes ATP; starts and end in PSI using an electron transport chain
step 1 - photosynthesis
light hits water in stroma, PSII and PSI all at once
- water splits into O2 (removed by stomata) and H+ then releases electrons
- PSII is energized by wavelength P680. Mg atoms lose 2 electrons that are collected in a primary collection protein and moved toward PSI with an electron transport chain.
- PSi is energized by wavelength P700 and Mg loses 2 electrons which are collected in another collection protein and moved to NADH+ along an electron transport chain.
step 2 - photosynthesis
electrons move down electron transport chain where 2 molecules are enter changing electrons (redox reactions) the molecule giving is oxidized, the molecule getting is reduced. redox reactions are powered by proton pump, concentration gradient drives reaction
PSII- free electrons move toward PSI using concentration gradient
PSI- free electron are used to reduce NADP+ to NADPH
step 3 - photosynthesis
trapped H+ ions in thylakoid membrane are released through ATP synthase complex. complex makes ATP by phosphorylation (ATP→ADP)
cytochrome C
a protein found in the inner cell membrane of all mitochondria, chloroplasts and plasma membrane of prokaryotes; supports common ancestry of cell organisms
step 1 - calvin cycle
CO2 + RuBP (sugar) = rubisco; makes 6 unstable carbon molecules that immediately split into 3 carbon molecules (3PGA)
step 2 - calvin cycle
6 ATP and 6 NADPH “bend” 3PGA twice into G3P (half a glucose molecule)
step 3 - calvin cycle
one G3P is removed and the other 5 are recycled; cycle repeats twice to make another G3P because glucose is 2 G3P
what is needed for each turn of the calvin cycle?
9 ATP and 6 NADPH
18 ATP and 12 NADPH for a whole glucose molecule
C3 plants
most plants
fix carbon in calvin cycle - CO2 + RuBP
Rubisco
most energy efficient method
loses the most water during photorespiration
C4 plants
tropical grasses, corn, and sugar cane
live in dry climates
fix carbon in cytoplasm - CO2 to PEP
PEP - ase
less energy efficient than C3 but more than CAM
loses less water than C3 but more than CAM
CAM plants
succulents, pineapple, agave
desert plants
only fix carbon at night, fix carbon to organic molecules
PEP - ase
best water conservation
how do C4 plants complete photorespiration?
PEP combines with CO2 using PEP-ase to make oxaloacetate. oxaloacetate is too big to enter bundle sheath cells so it converts to malate. malate releases CO2 to the calvin cycle. pyruvate is produced which can be turned back into PEP and reused.
how do CAM plants complete photorespiration?
during the day, CAM plants break down crassulacean acid to release CO2 to be used for the calvin cycle. process allows the stomata to stay closed in order to not loose water through transpiration.
cellular respiration
a process that is catabolic, exergonic, and requires oxygen to break down carbohydrates (glucose) to produce ATP and water
where does cellular respiration occur?
it occurs in the mitochondria of both autotrophs and heterotrophs
what is a redox reaction?
reactions that involve a transfer of electrons from one reactant to another during many chemical reactions
reduced and oxidized
reduced
when a molecule gains an electron (becomes more negative)
oxidized
when a molecule loses an electron to another molecule
parts of cellular respiration
glycolysis
oxidation of pyruvate
kreb’s cycle
electron transport chain
anaerobic
doesn't require oxygen to occur
glycolysis
the breaking down of sugar; occurs in cytoplasm (cytosol) near mitochondria; anaerobic; all organisms do glycolysis
10 steps in cytoplasm
oxidation of pyruvate
occurs in matrix of mitochondria; anaerobic
1 step in matrix of mitochondria
aerobic
requires oxygen to occur
kreb’s cycle (citric acid cycle)
occurs in mitochondrial matrix; aerobic
8 steps in mitochondrial matrix
electron transport chain
occurs in cristae; aerobic
multi - step process in mitochondrial membrane
cristae
inner membrane of mitochondria
energy investment phase
first 5 steps of glycolysis
glucose (6 carbon molecule) is split into two 3-carbon molecules (G3P/GAP - glycerhaldehyde phosphate)
2 ATP used; 0 ATP and NADPH produced
energy yielding phase
last 5 steps of glycolysis
each of the two G3P molecules is converted into pyruvate
0 ATP used; 4 ATP and 2 NADPH produced
how much energy is harnessed during glycolysis?
about 2%
is the energy harnessed during glycolysis enough?
for small organisms like bacteria, yes, but for large organisms, no.
what occurs if oxygen is present in the cell?
cellular respiration
what occurs if oxygen is not present in the cell?
fermentation
what are the two kinds of fermentation?
alcohol fermentation
lactic acid fermentation
alcohol fermentation
occurs in plants and fungi
human use it to make beer, wine, and bread (yeast)
end products:
2 ATP
2 CO2
2 ethanol’s
lactic acid fermentation
occurs in animals
build up causes muscle cramps and soreness
end products:
2 NADPH
2 lactate molecules
what occurs instead of fermentation when oxygen is present?
krebs cycle
grooming phase
happens to each glucose molecule that goes through glycolysis; 2 pyruvates are produced, oxidized, and transported into the mitochondrial matrix and converted to Acetyl CoA where they then enter the Kreb’s cycle
end products:
2 NADPH
2 CO2
2 acetyl CoA
what happens in the kreb’s cycle?
acetyl CoA bonds to oxaloacetic acid to make citrate. it takes two cycles to oxidize one glucose molecule. total net yield results in a pool of energy molecules that form from the oxidation of pyruvate
end products:
2 ATP
6 NADH
2 FADH2
4 CO2
electron transport chain and oxidative phosphorylation
occurs in cristae
ETC and ATP synthase make ATP
ETC pumps H+ across inner membrane and lowers H+ in the inner membrane space. this allows H+ to diffuse using the concentration gradient and ATP synthase to produce ATP.
all NADH and FADH2 are converted to ATP
NADH= 3 ATP
FADH2= 2 ATP
extra electrons are given to oxygen which combines with water
oxygen allows electrons to move across ETC to produce ATP; without oxygen the electron wold build up and stop diffusing into mitochondria thus stopping ATP production
total net yield for prokaryotic cells during cellular respiration
2 ATP- glycolysis
6 ATP-from 2 NADH (glycolysis)
6 ATP converted from 2 NADH (grooming phase)
2 ATP -Kreb's cycle
18 ATP -from 6 NADH (Kreb's cycle)
4 ATP - converted from 2 FADH, (Kreb's cycle)
38 Total ATP
total net yield for eukaryotic cells during cellular respiration
• 2 ATP -glycolysis
•4 ATP -from 2 NADH (glycolysis)
•6 ATP-from 2 NADH (grooming phase)
•2 ATP- Kreb's cycle
*18 ATP -from 6 NADH (Kreb's cycle)
•4 ATP- converted from 2 FADH (kreb’s cycle)
36 Total ATP
Note 
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