powering the cell part 1 Flashcards
what are the two ways cells are fuelled
1) carbon source
2) capturing energy from chemical reactions or light to produce usable energy
which macromolecule requires the most amount of energy to synthesise
protein
what is a heterotroph
cells which use organic compounds as a source of carbon as well as the source of energy
what is an autotroph
cells which use carbon dioxide as a source of carbon and light as a source of energy
what is a chemoautotroph
cells which use carbon dioxide as a source of carbon and inorganic compounds as a source of energy
outline the structure of ATP
3 phosphates
adenine base
ribose/pentose sugar
outline how ATP produces enegry
when hydrolysed with the addition of water the bond between phosphate 2 and 3 becomes unstable so ATP–> ADP which is an exogenic reaction, producing energy
how much energy is released when ATP goes to ADP
31 KJoules
what processes generate ATP
1) aerobic oxidation
2) fermentation/ anaerobic metabolism of glucose
3) photosynthesis
4) electron transport and proton motive force
outline how ATP is generated
1) the addition of a phosphate to ADP
2) electrons lost from a donor in reactions involving chemical substrates release energy
3) this is harvested to phosphorylate ADP to ATP
4) electrons move from a higher energy level to a lower one on the acceptor molecule, this movement released energy to phosphorylate
outline oxidative phosphorylation in chemotrophs
electrons move from a high energy level in a chemical molecule to a lower energy level in another molecule
the movement releases energy which turns ADP- ATP
outline photophosphorylation in phototrophs
light is used to excite photosynthetic pigments to move the electrons to an excited state which is unstable
therefore the electron is transferred to a lower energy level
what happens when a substance is reduced or oxidised
a substrate gains an electron so the positive charge is reduced
a substrate loses an electron so the positive charge is increased
define reducing power
the potential of a substance to reduce another substance by the loss or gain or an electron or by the addition or removal of hydrogen
what is a hydride ion
an ion made up of a proton (H+) and two electrons
outline how hydrogen is transferred
electrons in organic redox reactions are often transferred as hydride ions
therefore movement of an electron occurs in conjunction with the transfer of a proton
define dehydrogenation
the loss of electrons and protons from a substrate where they are transferred to a hydrogen acceptor such as NAD or NADP
outline how reducing power is used in the cell
NADH can be oxidised to NAD by the removal of electrons and transporting them through the electron transport chain via membrane proteins
at the same time a proton gradient is generated across the cell membrane which is used to generate energy
how much energy is needed to make reducing pwoer
219 KJ/mol
how many ATP molecules can be produced form one NADH
7
what is a bomb calorimeter
a lab instrument which measures the amount of energy in a substance by the heat released when combusted in an excess of oxygen
what are the steps of the oxidation of glucose and where do they occur
1) glycolysis - cytosol
2) pyruvic oxidation- mitochondiral matrix or cytosol (prokaryotes)
3) electron transport= inner mitochondrial membrane or plasma membrane (prokaryotes)
what is glycolysis and what is produced
= the conversion of glucose to pyruvic acid/ 2 pyruvates
1) 4 ATP (net 2 as 2 are used)
2) 2 NADH
3) hydrogen ions/protons
- 10 cytosolic enzymes are used to catalyse the reactions in this pathway
outline pyruvate oxidation and the krebs cycle
1) pyruvate is transported to the matrix where it reacts with coenzyme A forming carbon dioxide and acetyl CoA
2) the acetyl group of acetyl coA is oxidised to co2 via 9 reactions within the krebs cycle
what is produced in the krebs cycle
- 3 NADH
- 1 ATP
- 1 FADH
where is most the free enegry released in oxidation of glucose to co2 retained
- the reduced co enzymes NADH and FADH generated in glycolysis and the krebs cycle
where do the transporters for the ETC gain electrons
cytosolic NADH
outline electron transport
1) cytosolic NADH and FADH are oxidised to NAD and FAD
2) electrons are transported across a series of electron carriers in the inner membrane
3) this step by step transfer allows the energy in NADH and FADH to be released in small increments and stored as proton motive force
what is proton motive force
the force which promotes the movement of protons across the membrane as a result of an increased proton gradient in the intermembrane space
what is ATP synthase
an enzyme complex which uses proton motive force to generate ATP from ADP
outline the structure of ATP synthase
a membrane protien formed of two subunits, F0 and F1
- F0= hydrophobic and embedded in the membrane
- F1= is the head of the structure and exposed to cytosol
what does the F0 subunit of ATP synthase do
has a cavity which takes in protons where the lower portion Roates in response to ions moving down conc gradient across membrane
rotations of the F0 activated the F1 that binds phosphates to ADP to form ATP
outline the oxidation of fatty acids
- fatty acids stored as triacylglycerols are hydrolysed in the cytosol to free fatty acids and glycerol
- fatty acids and acetylcoA form fatty acetyl CoA which are oxidised in two ways which convert it to acteyl CoA and a shorter factty Actyel coA
1) FAD reduced to FADH and NAD reduced to NADH
2) cycle repeated until shortened fatty acteyl CoA complety converted to Acetylco A where it enters krebs
where are fatty acids oxidised in eukaryotes
mitochondria or perixomes
