Midterm 3 Flashcards
where can we get energy from?
protein, carbs (sugars), fat (lipids), nucleic acids
how does glucose enter a cell?
facilitated diffusion (proteins are used to help move molecules more quickly)
where does glycolysis take place?
in the cytoplasm!!
what are the main roles of glycolysis?
- energy generation
- production of pyruvate (high energy molecule that can be metabolized)
- synthesis of precursors for macromolecules (nucleic acids, amino acids, intermediates for other metabolic pathways)
what is the goal of fermentation?
reform NAD+ when. (when you run out of NAD+ during glycolysis, you cannot create NADH)
what is the universal cell energy source?
ATP
why is ATP a high energy compound?
- repulsion by negatively charged products (PO4^2-, ADP^2-)
- resonance stabilization of products
what is the role of Nicotinamide adenine dinucleotide? (NAD)
functions as an electron shuttle (involved in redox reactions)
why does glycolysis require ATP?
ATP is needed at the start of glycolysis to split the glucose molecule into two pyruvate molecules.
what are the products of glycolysis?
glycolysis involves the breaking down of a sugar (glucose) into more manageable compounds in order to produce energy. The net products of glycolysis are 2 pyruvate, 2 NADH, and 2 ATP
what happens to the products of glycolysis?
the pyruvate end product of glycolysis can be used in either anaerobic respiration (w/o oxygen) or in aerobic respiration via the TCA cycle which yields much more usable energy for the cell.
after glycolysis, where is most of the energy that was in the original glucose molecule?
the energy that had been stored in the now broken bonds, is transferred to 2 ATP and 2 NADH molecules
what happens to pyruvate if oxygen is not present? (humans & plants)
pyruvate ferments!! in plants, fermentation creates ethanol, and in animals fermentation creates lactic acid
how is a small amount of ATP made in glycolysis??
transfer of a phosphate group from a fragment of glucose to ADP by substrate-level phosphorylation
what is the most common mechanism that regulates cellular respiration in most cells?
feedback inhibition of glycolysis
most of the electrons removed from glucose by cellular respiration are used for which of the following processes?
reducing NAD+ to NADH in glycolysis and the citric acid cycle AND producing a proton gradient for ATP synthesis in the mitochondria.
in the overall process of glycolysis and cellular respiration ____ is oxidized, and ___ is reduced
glucose, oxygen
in what molecule is the majority of the chemical energy from pyruvate transferred during the citric acid cycle
NADH & FADH2
is a reducing agent oxidized or reduced? why?
oxidized because it loses electrons in the redox reaction, it reduces other substances and loses electrons, therefore the oxidation state increases
what is the difference between substrate level phosphorylation and oxidative phosphorylation?
substrate level- directly phosphorylating ADP with a phosphate and energy provided from a coupled reaction
oxidative- ATP generated from the oxidation of NADH and FADH2 and the subsequent transfer of electrons and pumping of protons
what is the first series in cellular respiration?
glycolysis!!
explain glycolysis step by step
1- start with glucose (6C molecule)
2-split glucose into 2 pyruvate (3C molecules)
3-2NAD coenzymes are going to take some of the high energy Hydrogens and attach them to oxygen to form H2O
4-this releases energy to form 4ATP molecules. 2 of the four molecules will go back to refill the previously spent energy.
5-if oxygen is present, the cell will go into aerobic respiration , if no oxygen present;fermentation
when does fermentation occur??
at the end of glycolysis if there is no oxygen present
what are some examples of anaerobic respiration??
alcohol fermentation, lactic acid fermentation, decomposition of organic matter
