Lectures 15&16 - Mitochondria and Chloroplasts Flashcards
What does the folding give the mitochondria
High SA
What are the parts of a mitochondria
Matrix
Cristae
Inner Membrane
IMS
Outer membrane
What are the parts of a chloroplast
Outer membrane
Inner Membrane
Thylakoid membranes (contains lumen)
Granum (stacks of thylakoids)
IMS
Stroma (space between inner and thylakoid membranes)
What is the main function of mitochondria and chloroplasts
ATP synthesis
What is the function of ATP produced in the mitochondria
Energy source for other cellular processes as a result of oxidation of foodstuffs
What is the function of ATP produced in the chloroplasts
Used in Calvin cycle in the fixation of CO2 into sugar
What is ATP used for
Anabolic reactions of cells responsible for growth and repair processes
Catabolic reactions release energy needed to drive anabolic reactions
Must be an efficient linking or coupling of energy yielding to energy requiring processes
ATP is most commonly used as this energy intermediate
Energy currency of the cell
Transfers the energy captured during cellular respiration to the cellular sites that use energy
Where is ATP synthase found
mitochondrial inner membrane, the chloroplast thylakoid membrane and the inner membrane of eubacteria
Describe the structure and function of ATP synthase
Large lollipop head is attached through a stalk to the transmembrane carrier for protons
As protons pass through the carrier it is thought that the stalk spins inducing the head to produce ATP
(F0 portion allows protons to flow through, turning stalk - F1 subunit then converts ADP +Pi to ATP)
(slide 9)
A proton gradient is a form of stored energy. What are its two components
Difference in voltage across a membrane (membrane potential
Difference in proton concentration
What is the maths behind ATP synthase
Can produce around 100 molecules of ATP/second
Around 3 protons are needed to synthesise 1 molecule of ATP
Can be reversed, ie use the hydrolysis of ATP to pump protons
Conformational changes in ATP synthase
Slide 12
Where is the ATP synthesised in the chloroplasts
Stroma
Where is the ATP synthesised in Mitochondria
Matrix
How is the proton gradient across the mitochondrial membrane generated
ETC
High energy electrons are passed along an electron transport chain
These electron transfers release large amounts of energy which is used to pump H+ across the membrane creating an electrochemical proton gradient
Describe the structure of the proton pumping completes in the mitochondria
NADH dehydrogenase
Cytochrome bc1 complex
Cytochrome oxidase complex
Fats and Carbohydrates enter citric acid cycle, losing 2e-
2e- create an ETC with NADH donating protons, through the 3 complexes then H+ binds with oxygen to form water
What does NAD stand for
Nicotinamide adenine Dinucleotide
What are some mobile electron carriers and their functions
Move electrons between respiratory chain complexes
Ubiquinone carries electrons from the NADH dehydrogenase to the cytochrome b-c1 complex
Cytochrome c carries electrons from the cytochrome b-c1 complex to the cytochrome oxidase complex
What is chemiosmotic coupling
The linkage of electron transport, proton pumping and ATP synthesis
In mitochondria this process is known as oxidative phosphorylation
How are reducing agents ranked
Reducing agents ranked according to electron transfer potential
NADH has high electron transfer potential (-ve value)
H2O has low electron transfer potential (+ve value)
Standard redox potential E’0 (measured in Volts)
DG0’ = -nFDE’0
G (Free energy)
E (Redox potential
N+= no of electrons
F= Faraday constant
What happens to the redox potential (electron affinity) along the mitochondrial electron transport chain
Increases
What are the metal sensors in electron carrying groups
NADH dehydrogenase: Flavin nucleotides, Fe-S
Cytochrome bc1 complex: Heme, Fe-S
Cytochrome c: Heme
Cytochrome oxidase complex: Heme, CuA, CuB
