Lecture #9 - Aerobic respiration etc Flashcards
Why does a cell need energy? (5 things)
- To do WORK
- Make new MATERIALS
- GROWTH and replacement
(work consumes energy, making new materials is the ‘work’ and growth/replacement requires materials)
- MOVEMENT - whole body ( muscle - resist weight etc) or within cell (transport via motor protein)
- PUMPING substances across membranes (accumulates materials and generates gradients)
Co-transport example
Bring glucose into cell:
- Take H+ and push it out of cell (use ATP) - H+ conc gets higher outside cell
- H+ then comes back down conc and when it does - they pull sucrose with them
Energy is also required to maintain what?
Order
Where is the cell’s energy generated?
- The cytosol (glycolysis - breaking down of glucose)
- The mitochondria (matrix) (citric acid cycle)
- Mitochondrial membranes (inter membrane space) (oxidative phosphorylation)
How is cell’s energy generated?
CELLULAR RESPIRATION
• releases the chemical energy stored in food (our only source of energy)
• converts this into small (useable) units
• carried by the energy transfer molecule ATP
Mitochondria
- How long?
- How many in a cell?
- Enclosed by what?
- What does it contain?
- What does it produce other than energy?
- What movements/actions
- May form what?
- 1 -10 μm long
- 1 - 1000’s per cell:- depends on energy demand
- Enclosed by two lipid bilayers
• membranes contain special proteins
• inner membrane highly folded:- cristae - Contains mitochondrial DNA and ribosomes
- Produces some but not all mitochondrial proteins (hence lives inside cell and isn’t independent)
- Mobile within the cell - can changes shape to big or small, fuse or divide when cell needs more
- May form branched interconnected networks
Mitochondrial compartments are important for what?
Energy generation
Cytosol:
- What process takes place here?
- Releases how much energy?
- And transfers what?
- Glycolysis - reduces food molecules (glucose) into smaller units
- Releases some energy (2 ATP per glucose)
- Transfers electrons to the electron carrier NAD
Mitochondrial compartments are important for what?
Energy generation
Matrix
- What occurs here?
- What is being processed here?
- Releases how much energy?
- Transfers what?
- Why have organelles?
- Citric acid cycle (Krebs Cycle)
- Processes pyruvate
- Releases more energy (2 ATP per glucose)
- Transfers more electrons to NAD and FAD
- Concentrate enzymes and substrates that make the Kreb cycle work
Intermembrane space
- What occurs here?
- Releases how much energy?
- Why have organelles?
- Oxidative phosphorylation (electron transport and chemiosmosis)
- Releases more energy (26-28 ATP per glucose)
- To generate a conc grad and use this to power ATP formation (cycle couldn’t happen if no mito bc everything would be too far away)
So, for the simplified version of the H+ coming down their conc grad - explain it (dumbed down version)
Outer membrane
Inter membrane space
Inner membrane - has 3 proteins and all are pumps and require energy (electrons) to work. Pumping one H+ doesn’t use all the energy so the energy gets passed from one protein to another (e transport chain).
-The ATP synthase is a channel protein that opens when enough H+ ions outside and come down grad - the turbine thing captures the ene.
Matrix
My version of Oxidative phosphorylation
Electron transport chain - NADH tranfers e- to complex I and becomes oxidised to NAD+. FADH2 transfers its e- to complex II and becomes oxidised to FAD. The e- that go through the chain come back to complex IV (last one) and bind with 1/2O2 + 2H+ (the H+ come from (aq) solution) and become 1H2O.
Chemiosmosis - ATP synthase - H+ pass down and it turns ADP into ATP
What are the equivalent structures in mito and chloro?
Inter membrane space = thylakoid space (higher conc of H+)
Inner membrane = thylakoid membrane
Matrix = stroma (lower conc of H+)
Oxidative Phosphorylation
- NADH and FADH2 transfer electrons to the electron transport chain. Electrons move down the chain, losing energy in several energy-realising steps. Finally, electrons are passed to O2, reducing it to H20.
- At certain steps along the electron transport chain, electron transfer causes protein complexes to move H+ from the mitochondrial matrix (in eukaryotes) to the inter membrane space, storing energy as a PROTON-MOTIVE FORCE (H+ gradient). As H+ diffuses back into the matrix through the ATP Synthase, its passage drives the phosphorylation of ADP to form ATP in a process called chemiosmosis
