3 - Energy Generation in Mitochondria and Chloroplasts

catabolism

most of the energy stored in chemical bonds of food is dissipated as heat

anabolism

energy is converted into useful forms needed to drive the synthesis of new molecules

spontaneous tendency towards…

disorder

second law of thermodynamics

intervention required will release enough heat to the environment will compensate for the reestablishment of order

heat released into the environment increases disorder by…

increasing thermal motion, vibration, and rotation of those molecules

first stage of photosynthesis

activated carriers, ATP and NADPH, are generated

second stage of photosynthesis

chemical bond energy is formed and stored via photosynthesis in the form of sugars

photosynthesis

• in chloroplasts

• process that uses the energy of sunlight to make sugars and other organic molecules from the carbon atoms in CO2 via a proton gradient

cell respiration

process that uses O2 to oxidize food molecules, releasing carbon in the form of CO2 to gain chemical-bond energy

oxidation

replacement of its hydrogen atoms with oxygen atoms

electrons shifted away from the carbon

reduction

oxygen atoms are replaced by hydrogens

oxidative phosphorylation

• in mitochondria

• electron transport system that uses energy derived from the oxidation of food to make a proton gradient across a membrane

a proton gradient drives…

atp synthesis

chemiosmotic coupling process

1. proton pump harnesses the energy of electron transfer to pump protons across a membrane, making a gradient

2. the proton gradient serves as an energy store to make atp via atp synthase

PROTONS COME FROM H2O

mitochondria divide like…

bacteria (fission)

similarities btwn mitochondria and chloroplasts

• DNA based genome and ability to replicate DNA to make RNA/protein

• inner compartments (mito matrix, chloroplast stroma) have DNA and ribosomes

• membranes in both organelles (mito inner membrane & chloroplast thylakoid membrane) contain protein complexes involved in ATP production

where are mitochondria located in a cardiac muscle cell?

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

CONCEPT: mitochondria are located near sites of high ATP demand

where are mitochondria located in the sperm?

near the tail (wrapped around flagellum)

mitochondria transport via…

microtubule based/axonal transport

where are mitochondria located in neurons?

at the nodes of ranvier bc the high density of na+ and na+/k+ atpases (to conduct high velocity nerve impulses and repetitive firing)

four compartments of mitochondria

matrix

inner membrane

outer membrane

intermembrane space

matrix

highly concentrated mix of enzymes (used for pyruvate oxidation, fatty acids, CAC)

inner membrane

contains cristae (folds), proteins that carry out oxidative phosphorylation, ETC, atp synthase; and transport proteins

outer membrane

contains porins (large, channel forming proteins)

permeable to molecules of 5000 daltons or less

intermembrane space

contains enzymes that use the atp passing out of the matrix to phosphorylate other nucleotides and proteins released during apoptosis