3.3 - E in mitochondria + chloroplasts

catabolism

a major portion of the energy stored in the chemical bonds of food molecules is dissipated as heat

• some E used to drive new molecule synthesis in anabolic pathways!

what maintains biological order?

the 2nd law of thermodynamics

• human intervention will release enough heat to bring back order

biological order steps

1. molecules of cell + env are relatively disordered

2. cell takes E from food → carries out order rxn → releases heat into env

3. heat incr. disorder in surroundings

different forms of energy are interconvertible but the total amount of energy must be ………………

conserved

trapped by plants and some microorganisms through photosynthesis ………… is the ultimate source of all energy for humans and other animals

sunlight

2 stages of photosynthesis

• stage 1

activated carriers are generated in the first stage, ATP and NADPH

2 stages of photosynthesis

• stage 2

chemical-bond energy can be formed and stored via photosynthesis

photosynthesis general process

sun E → H2O + CO2 → O2 + sugar

cell respiration

O2 + sugar → CO2 + H2O

membrane-based mechanisms definition

use the energy provided by food or sunlight to generate ATP

• this is how cells obtain most E

oxidative phosphorylation

• membrane-based mechanism

in mitochondria

• electron-transport system uses energy from oxidation of food to generate a proton (H+) gradient across a membrane

photosynthesis

• membrane-based mechanism

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in chloroplasts

electron-transport system uses energy derived from the sun to generate a proton gradient across a membrane

if a battery’s terminals are directly connected………, the energy released by electron transfer is all converted into heat

to eachother
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if a battery is connected …………., much of the energy released by electron transfer can be harnessed to do work

to a pump

membrane-based mechanisms

• step 1

proton pump harnesses E of electron transfer to pump protons (H+) across a membrane

• creates proton gradient

membrane-based mechanisms

• step 2

proton gradient serves as E source that can be used to drive many E-requiring reactions

• in mitochondria, chloroplasts and prokaryotes

• SYNTHESIS OF ATP BY SYNTHASE

a ………. can divide like a bacterium

mitochondria

similarities between mitochondria and chloroplasts

• have their own DNA-based genomes + replication machinery

• inner compartments have DNA + ribosomes

• membranes contain protein complexes involved in ATP production

where is the mitochondria in a cardiac muscle cell

close to the contractile apparatus, where ATP hydrolysis provides the energy for contraction

where is the mitochondria in sperm

in the tail, wrapped around a protion of the motile flagellum that requires ATP for movement

role of mitochondria in nodes of Ranvier

stationary at the node and serve as energy sources to support Na+/K+ ATPases

4 comparments of mitochondria

1. matrix

2. inner membrane

3. outer membrane

4. intermembrane space

mitochondrial matrix

contains highly concentrated mixture of enzymes

• required for oxidation of pyruvate + fatty acids and citric acid cycle

mitochondrial inner membrane

contains proteins that carry out oxidative phosphorylation

• electron transport chain

• ATP synthase

• transport proteins that move selected molecules in + out of matrix

mitochondria outer membrane

contains large, channel-forming proteins

• permeable to all molecules of 5000 daltons/less

mitochondria intermembrane space

contains several enzymes that use ATP passing out of matrix to phosphorylate other nucleotides