Cellular Metabolism Flashcards
Glycolysis
is the first stage of aerobic and aerobic respiration
- series of reactions that breaks down 6 carbon glucose into two 3 carbon pyruvate.
- 2 ATP and 2 NADH are also made.
- glycolysis works in both the presence and absence of oxygen.
- reactions of glycolysis occur in the cytosol.
what is the first phosphorylation?
glucose to glucose 6 phosphate - not necessarily permanent here to glycolysis bc it can be made into glucose 1 phosphate and then made into glycogen.
but then SECOND phosphorylation occurs where its converted to fructose 6 phosphate- which is phosphorylated and turns into furctose 1,6 biphosphate
this step is irreversible and commits the molecule to the glycolysis pathway
what is fermentation?
aerobic respiration. it includes glycolysis. reduction of pyruvate to ethanol or lactic acid and the oxidation of the NADH back to NAD+ . yeast and some microorganisms make ethanol, human muscle cells and other microorganisms make lactic acid.
when does fermentation take place?
when a cell is either unable to get energy from MADH and pyruvate or no oxygen is available . in fermentation, NAD+ is restored for use in glycolysis as a coenzyme and the lactic acid or ethanol with CO2 is expelled from the cell as waste.
ethanol is ___ C molecule
2 (pyruvate 3 C is covered to ethanol or lactic acid in fermentation)
lactic acid is a ___C molecule
3
aerobic respiration
needs oxygen , if it is present then the products of glycolysis (pyruvate and NADH) will move into the mito matrix. the outer mito mem is permeable and these molecules pass thru via porins. the inner mem is less permeable. pyruvate moves into the matrix via facilitated diffusion, each NADH might need ATP hydrolysis.
what happens once these products are in the matrix?
prruvate is converted to acetyl coA , in a reaction that will make CO2 and NADH
What is acetyl coa?
its a coenzyme that will transfer two carbons from the pyruvate to 4 c oxaloacetate to start the Krebs cycle or TCA.
what does each turn of TCA make?
ATP 1
NADH 3
FADH2 1
This occurs via substrate level phsophorylation. during the cycle 2 carbons are lost as CO2 and oxaloacetate is reproduced again to begin TCA
How many times does TCA turn?
twice ! once for each pyruvate made
how are triglycerides used?
fatty acids are converted to acyl COA along the outer mito mem and ER at expense of one 1 ATP. they re bought into the matrix , and two carbons are cleaved at a time to make acetyl coA from acyl COA. this reaction also makes FADH2 and NADH for every 2 carbons taken from the original fatty acid. acetyl coa then enter TCA as usual.
what about amino acids?
they are deaminated in the liver. deaminated product is either chemically converted to pyruvic acid or acetyl coA, or it may enter TCA at various stages depending upon which amino acid was deaminated.
nucleotides must also be deaminated before entering TCA as one of its intermediated.
what is the ETC (electron transport chain)?
series of proteins , including cytochromes with heme, in the inner mem of the mitochondria. the 1st protein will oxidize NADH by accepting its high energy electrons. electrons are then passed down the protein series and ultimately accepted by oxygen to form water.
what happens as the electrons are passed down?
the protons are pumped into the intermembrane space for each NADH. this establishes a proton gradient which propels the protons through ATP synthase to make ATP production of ATP in this manner is called oxidative phosphorylation.
