Cellular respiration
Metabolism
sustaining chemical reactions in a cell
conservation of food energy into cellular energy (ATP)
energy that the cell can utilize
complex process
What are the 2 types of metabolic pathways
Catabolic and anabolic
Catabolic Pathways
Break down of cellular components
Exergonic - release’s energy
Spontaneous
stored in ATP and NADH
Larger molecules broken down into smaller molecules
Anabolic Pathways
Synthesizing cellular components
Endergonic
Requires energy input to drive reactions
makes larger macromolecules not available in food
small molecules to large ones
ATP
Has 3 phosphate groups
energy is stored in the bonds in phosphate groups
lots of negative energy
lots of potential energy
cycle between ATP and ADP
When bonds are broken that is when energy is used.
NADH
Energy intermediate
Accepts electrons and protons removed from organic molecules
high energy
NAD+
carrier molecule
transfers electrons and protons to where they need to be in the cell
Hydrogen is coming from glucose or other substrate molecules
2 electrons 1 proton
Redox reactions
reactions involving an electron transfer - changing the nature of a molecule
oxidation - removal of electrons
Reduction - Addition of electrons (reducing charge)
OILRIG oxidation is loss, reduction is gain
EX: Ae- + B —> A + Be-
A is being oxidized B is being reduced
Gene Regulation
Turns genes on and off
Cell Signaling Regulation
cell signaling pathways often activate protein kinases
Biochemical Regulation
Feedback inhibition
Feedback inhibition
product of a pathway inhibits early steps to prevent over accumulation of a product
many enzymes involved
Structure = function
living organisms maintain homeostasis
Overview of cellular respiration
Process by which living cells obtain energy from organic molecules
used by plants and animals
primary goal is to make ATP and NADH
Aerobic Respiration
uses oxygen
What are the 4 metabolic pathways
Glycolysis
Breakdown of pyruvate
Citric Acid Cycle
Oxidative phosphorylation
Glycolysis overview
stage 1 of cellular respiration
only step that does not happen in the mitochondria
happens in the cytosol
can occur with out oxygen but will not move on to the next stage
Has 10 steps that will happen in 3 phases
Energy investment
Stage 1 in glycolysis
2 ATP hydrolyzed to create fructose 1, 6-bisphosphate
steps 1-3
Cleavage
Stage 2 in glycolysis
6 carbon molecules broken down into 3 carbon molecules of glyceraldehyde 3- phosphate
steps 4-5
Energy liberation
Stage 3 in glycolysis
2 glyceraldehyde 3- phosphate broken down into 2 pyruvate molecules that produce 2 NADH and 4 ATP
Steps 6-10
Net Yield: 2 NADH and 2 ATP because the other 2 ATP go back to the first stage
Breakdown of pyruvate
Stage 2 of cellular respiration
pyruvate is transported into the mitochondrial matrix through the outer membrane channel
Broken down via enzymes pyruvate dehydrogenates
molecule of CO2 removed from each pyruvate
Remanning acetyl group attached to CoA to make Acetyl CoA - this is what is left of pyruvate
Yield = 1 NADH for each pyruvate (2)
Citric Acid Cycle
Stage 3 of cellular Respiration
Metabolic cycle
some molecules enter while others leave
series of organic molecules regenerated in each cycle
Acetyl CoA starts the cycle
series of steps releases - 2CO2, 1ATP, 3NADH, 1FADH2 - per pyruvate so times 2
Acetyl is removed from acetyl CoA and detached from the citrate
Oxidative Phosphorylation
stage 4 of cellular respiration
high energy electrons removed from NADH and FADH2 to make ATP
requires oxygen
oxidation by the electron transport chain
protein complexes embedded in the inner mitochondrial membrane
accepts and donates protons and electrons in a series of redox reaction
movements of electrons generates an H+ electron gradient
providing energy for the next step
water is produced during movement of electrons through ETC
oxygen is the final electron acceptor
Phosphorylation by ATP synthase
phosphorylation - the addition of a phosphoryl group to a molecule - makes ADP —> ATP
protons can only pass through ATP synthase - only way hydrogen ions can move back across bilayer
ATP synthase
chemmiosmosis - chemical synthase of ATP as a result of pushing H+ across membrane
ATP synthase captures free energy as H+ ions flow through
Big energy pay off
NADH and FADH oxidation makes most of the cells ATP
NADH and FADH oxidation makes most of the cells ATP
Yield up to 30-36 ATP - rarely achieve maximal amounts because
NADH is also used in anabolic pathways
H+ gradient used for other purposes
Where does glycolysis occur
Cytosol
what is the end product of glycolysis
pyruvate
What is the net yield of energy containing molecules per 1 glucose in glycolysis
2 ATP
4 NADH
Where does the breakdown of pyruvate occur
mitochondria
what is the end product of the breakdown of pyruvate
Acetyl CoA
What is the net yield of energy containing molecules per 1 glucose in the breakdown of pyruvate
2 NADH
Where does the citric acid cycle occur
mitochondria
what is the end product of the citric acid cycle
oxolacitate is regenerated
What is the net yield of energy containing molecules per 1 glucose in the citric acid cycle
4 Co
2 ATP
6 NADH
2 FADH2
Where does oxidative phosphorliation occur
inner mitochondrial membrane
what is the end product of oxidative phosphorliation
NAD+
FAD+
H2O
What is the net yield of energy containing molecules per 1 glucose in oxidative phosphorliation
30-36 ATP
Anaerobic organisms
do not need oxygen
are used for anaerobic respiration and Fermentation
Ex: bacteria
Facultative Anaerobe
uses aerobic respiration when there is oxygen but can survive anaerobic
Anaerobic respiration
Bacteria and archaea can us other e- accepters
has donners besides glucose
substituting oxygen with different electron receptors
Still use ECT and ATP synthase in the mitochondrial membrane
Fermentation
has 2 steps
glycolysis
Regeneration of NAD+
What are problems with fermentation
high concentrations
NADH haphazardly donates it protons and electrons to other molecules
decrease in NAD+
What are the solutions to fermentation
Lactic acid fermentation
alcohol fermentation
Lactic Acid fermentation
pyruvate is reduced to make lactate
electrons are used to reduce pyruvate are derived from NADH which is oxidized to NAD+
alcohol fermination
pyruvate is turned into alcohol
pyruvate is broken down into Co2 and 2 carbon molecule — acetaldehyde
acetaldehyde is then reduced by NADH to make ethanol
NADH in then oxidized to NAD+
How many ATP can fermentation make
2 ATP
What are the 2 trophic levels
heterotroph
Autotroph
What is a heterotroph
must eat food to sustain life
Autotroph
makes organic molecules from inorganic sources
most are photoatrophes that use light as enegy
Mesophyll cells
where a majority of photosynthesis occurs
most of the cells in a plant
Stomata
carbon dioxide enters and oxygen exits through pores in the leaf
oxygen can leave trough them to
chloroplast
organelle in plants and algae that caries out photosynthesis
chlorophyll is found in here
Thylakoid (Chloroplast anatomy)
a third membrane
contains pigment molecules
membranes form thylakoids
Granum (Chloroplast anatomy)
stack of thylakoids
Stoma (Chloroplast anatomy)
fluid filled region between thylakoid membrane and inner membrane
Lumen (Chloroplast anatomy)
region inside the thylakoid membrane
What are the two stages of photosynthesis
light reaction
Calvin Cycle
Light energy
light is a type of electromagnetic reaction
travels as waves
short to long wavelengths
behaves as particles called photons
discrete packets
shorter wavelengths have more energy
Photons
discrete packets
shorter wavelengths have more energy
can be absorbed transmitted or reflected when they strike an object
Pigments
molecules that absorb only certain wavelengths of light
Electrons capturing light energy
absorption boost energy to higher energy levels
after an electron absorbs energy it is in an excited state and usually unstable
it does not want to be here
How does an release energy (3 ways)
heat
light
excited electrons can be transferred to another molecule
Chlorophyll pigments
are the most common
red and blur photons can be absorbed
work in groups
200-300 chlorophyll molecules and accessory pigments organized by many proteins to form antenna complex
what are some accessory pigments
Chlorophylls
Carotenoids
xanthophylls
what do light reactions use
light energy
H2O
What do light reactions produce
O2
NADPH
ATP
What is NADPH used for in light reactions
an electron carrier
What is ATP used for in light reactions
can store and transport energy
What are the 2 main components in the structure of photosystems
antenna complex
reaction Center
Antenna complex
directly absorbs photons
energy transferred via resonance energy transfer
Reaction Center
energy is transferred quickly
Electron transfers to a primary electron acceptor and captured
PSII P680 —> P680* (P680* is relatively unstable)
PSI P700 —> P700* (P700* is relatively unstable)
Photosystem II
The initial step in photosynthesis
light excites an electron
releases energy via the electron into the electron transport chain
What does photosystem II create
oxygen
oxygenic photosynthesis
happens in photosystem II
Is the only protein complex able to break water apart in this way
Electron transport chain (photosystems)
happens in steps 2-4 of photosystem
leave PSII and into the ECT
series of molecules that carry electrons
energy released drives H+ into the lumen
via the cytochrome complex
Used to make ATP
Photosystem I
Primary role to make NADPH
the same electron from PSII is now being re-excited by light
Same process but now uses a different reaction center
Electron combines with NADP+ and a H+ to form NADPH
the enzyme in NADP+ reductase
Aids in the process of turning NADP+ into NADPH
Z Scheme
Zigzag shape of energy curve
ATP synthesis in chloroplasts
achieved by a mechanism called photophosphorlation
Driven by the flow of H+ from thylakoid lumen into stroma via ATP Synthase
what are the 3 ways H+ gradient
^ H+ in thylakoid lumen by slitting of water
^ H+ by ETC pumping H+ into lumen
(down) H+ in stroma from formation of NADPH
What are the 3 chemical products in light reactions
oxygen,O2
NADPH
ATP
Synthesizing carbohydrates via the Calvin cycle
CO2 incorporated into carbohydrates
precursors’s to other organic molecules
energy storage
Requires massive energy input
In the calvin cycle how many ATP and NADPH must be used for every 6 CO2
18 ATP
12 NADPH
What is the final product of the calvin cycle
glyceraldehyde-3-phosphate
glucose is later made from G3P in separate process
What is the first phase of the Calvin cycle
Carbon Fixation
What is carbon Fixation
CO2 incorporated into RuBP using ribisco
reaction product is six-carbon intermediate that splits into 2 3-phosphoglyceralde
What is phase 2 of the calvin cycle
Reduction and carbohydrate production
what is Reduction and carbohydrate production
ATP is used to convert 3PG into 1,3bisphosphoglycerate
NADPH electrons are reduced to glyceraldehyde - 3 phosphate
6 CO2 —> 12 G3P
only 2 G3P molecules used to make carbs
10 G3P molecules must be used for regeneration of RuBP
What is phase 3 of the calvin cycle
Regeneration of RuBP
what is Regeneration of RuBP
10 G3P are converted into 6 RuBP using 6 ATP
what is the CO2 fixing enzyme is
Ribulose 1,5 bisphosphate carboxylase/oxygenase
What is rubisco
Found in all photosynthetic organisms that use the calvin cycle to fix carbon
thought to be the most abundant enzyme on the earth
What are environmental conditions that can cause variations in photosynthesis
light intensity
temperature
water availability
when are stomatas usually open and closed
open during the day
closed during nights
What does closing the stoma cause
CO2 delivery, and thus the calvin cycle stoping
Photorespiration
using oxygen instead of CO2
this is not efficient
C3Plants
plants that require 3-phosphoglycerate
90% of plants
C4 photosynthesis
used in hot and dry climates
spatial separation of 2 carbon fixation paths
CAM ( crassulacean Acid Metabolism)
temporal separation of 2 carbon fixation pathways
open stomata at night
conserve water
CO2 enters and is converted to oxaloacate
oxaloacate converted to malate
malate broken down into CO2 to drive calvin cycle during the day
Mesophyll cells in C4 plants
co2 enters via stomata and 4 carbon compound formed
Bundle sheath cell
4 carbon molecule transformed that releases steady supply of CO2 minimizing photorespiration