topic 5 - organotrophy Flashcards
what is aerobic respiration
combustion reaction
glucose is “burned” in O2 to produce CO2, water, with the release of heat
series of coupled redox reactions that release the free energy of glucose and transfers energy to other molecules (NADH, FADH2, ATP) and products
what is the difference between oxidation and reduction
oxidation = loss/partial loss of e-
reduction = gain/partial gain of e-
what happens during coupled redox reactions
non polar covalent bonds in the reactants are broken
polar covalent bonds in the products are formed
what happens during the coupled reactions in aerobic resp
bonding e- shared equally between the C atoms in glucose have moved further away from the C nuclei in CO2
- glucose is oxidised as it forms CO2
bonding e- shared equally between the O atoms in O2 have moved closer to the O nuclei in water
- O2 is reduced as it forms water
what is the importance of the nicotinamide ring in NAD+
important in gaining / losing e-
molecule gains 2 e- and 1 proton through reduction to NADH
what is the importance of flavin ring in FAD+
helps it gain 2 e- and 2 protons
what is reduction potential
production of NADH/FADH2
what is a reduced e- carrier
e- transport molecules that move e- from one reaction to another
transports energy in the form of high energy e-
where does glycolysis occur
present in all - archaea, bacteria, and eukarya
occurs in the cytosol
what is glycolysis
partial oxidation of glucose
occurs through 10 connected reactions (product becomes substrate)
each reaction is catalysed by an enzyme
what are the energy requiring reactions and energy releasing reactions in glycolysis
energy requiring
- glucose (6C) —> 2 G3P (3C)
- uses 2 ATP
energy releasing
- 2 G3P (3C) —> 2 pyruvate (3C) + 2 H2O
- releases 2 NADH and 4 ATP
what is the net ATP of glycolysis
2 ATP
(2 used, 4 created)
how are e- carriers reduced in glycolysis
proton and 2 e- from G3P are transferred to NAD+ to make NADH
what is substrate level phosphorylation
have:
- phosphorylated organic/reactant molecule
- ADP
- enzyme (not ATP synthase)
GENERATES ATP (how ATP is made in glycolysis)
2 molecules bind together in an enzyme active site and catalyse the transfer of P from a organic molecule of ADP to make ATP
what happens after glycolysis
not much ATP made - lot of energy still trapped in pyruvate
cell needs to remove pyruvate - don’t want final product build up in the cell
cell needs to restore NAD+ - need a way to oxidise the NADH made in glycolysis
what is fermentation
anaerobic reduction of pyruvate
when and where does fermentation occur
if O2 is limiting - pyruvate enters a fermentation pathway
occurs in eukaryotic and prokaryotic
occurs in cytosol
what is the main goal of fermentation
to oxidise NADH to NAD+
what is involved in lactate fermentation
reduce pyruvate to lactate (gains H+ atoms)
coupled to oxidation of NADH to NAD+
allows for glycolysis to continue (more NAD+ to support another round)
what is involved in alcoholic fermentation
pyrvuate decarboxylated - CO2 molecule removed
acetaldehyde reduced to ethyl alcohol (H atoms added)
coupled to oxidation of NADH to regenerate NAD+
products = ethanol and CO2
where is the inner membrane compartment / space (IMS) located
space between inner and outer membranes
what occurs in the mito matrix (inside both membranes)
pyruvate oxidation and citric acid cycle
what happens on the inner mito membrane
electron transfer
ATP synthesis
how does pyruvate get into the mito matrix
facilitated diffusion to get across outer mito membrane
high concen of pyruvate in matrix
secondary active transport (symport) with H+ moving from high to low to pull pyruvate across inner mito membrane
what is pyruvate oxidation
bridge reaction - connects glycolysis and CAC
- release of CO2 (decarboxylation)
- e- lost reduce NAD+ to NADH
what are the inputs and outputs in pyruvate oxidation
inputs
- pyruvate, NAD+, CoA
outputs
- acetyl coa (2C), NADH, CO2 (1C lost)
(still lots of PE in acetyl group)
what is the role of coenzyme A
involved in lots of pathways
carries around 2C units
what is the goal of the CAC
fully oxidise the C in acetyl coa to produce CO2
finish the oxidation of glucose to CO2
what is the overview of the CAC
8 connected reactions (some coupled)
oxidise acetyl coa to CO2
oxaloacetate (4C) combines with acetyl group (2C) to form citrate (6C)
for each molecule of glucose - go through CAC twice (double inputs and outputs)
what are the inputs and outputs for ONE turn of the CAC
input
- acetyl coa, 3 NAD+, ADP, FAD
output
- 2 CO2, 3 NADH, ATP, FADH2
(CO2 considered waste)
where is the useable energy from the original glucose molecule after the CAC
NADH
how is ATP generated by the CAC
substrate level phosphorylation
where do the NADH and FADH2 from CAC go
transport e- to the ETC
can only glucose be broken down into these pathways
no just glucose
proteins
- can be broken down into pyruvate/acetyl coa and CAC intermediates
fats
- can enter glycolysis and be broken down into acetyl coa
intermediates of the CAC can be used to build proteins or fats
where does glucose go if the body doesn’t need ATP
glucose stored as polymer short term (glycogen in animals, starch in plants)
triglycerides can be generated for even longer term storage
process can be reversed if ATP needed
what do organisms need C for
amino acids, proteins, nucleic acids, and lipids
how does aerobic resp in prokaryotes occur
all metabolism occurs in the cytosol and on the cell membrane
glycolysis, pyruvate oxidation, and CAC in cytosol
ETC on inner cell membrane with proton gradient made between the inner and outer membrane
pathways are the same
