UNCW Bio201 Exam #2- Chapters 5, 6, and 7
Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed during glycolysis?
100%
How many ATP and NADH molecules are produced from each molecule of glucose in the citric acid cycle only (do not consider pyruvate oxidation)?
2 ATP, 6 NADH
What is the optimal temperature for most enzymes to work at?
37 degrees Celsius
What is a proteasome?
A large complex that breaks down proteins using protease enzymes.
What must pyruvate be converted to before it can enter the Krebs cycle?
Acetyl-CoA
Which of the following statements is TRUE of both aerobic and anaerobic respiration?
Both use glycolysis to oxidize glucose to pyruvate and both produce NADH as high-energy intermediates.
Role of Catabolic Pathways
Breakdown cellular components; Exergonic
What process best characterizes Ca2+ movement from the cytosol (low Ca2+ concentration) into the endoplasmic reticulum (high Ca2+ concentration)?
Calcium movement involves active transport.
The equation, C6H12O6 + 6O2 =6CO2 + 6H2O (creation of 38 ATP + Heat), describes what process?
Cellular respiration
What is the role of proteases?
Cleave bonds between amino acids.
What direction does actin spin when ATP is being produced?
Clockwise
What direction does actin spin when ATP is being hydrolyzed?
Counterclockwise
What is the role of the proteasome?
Cylinder shaped; breaks down and recycles proteins.
A reaction that has a positive ΔG is described as...
Endergonic
What happens when temperature is too high for an enzyme?
Enzymes can unfold and lose their 3D shape.
If products have less free energy than the reactants, meaning ΔG is negative, the reaction is described as...
Exergonic
What compound has the highest free energy and produces the most ATP per molecule when oxidized?
Glucose
Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?
Glycolysis
Where does glycolysis occur?
In the cytosol of the cell
Na+ ion concentrations are higher outside the cell than inside the cell. What type of transport system is required to move Na+ ions in and out of the cell?
Na+ moves into the cell by facilitated diffusion and out of the cell by active transport
An endergonic reaction is... (spontaneous/not spontaneous)
Not spontaneous
passive transport
Requires NO energy, Movement of molecules from high to low concentration, Moves with the concentration gradient
During glycolysis, when glucose is catabolized to pyruvate, most of the energy of glucose is
Retained in the Pyruvate
The primary complexes for protein synthesis and degradation in eukaryotes are ____and _____respectively.
Ribosomes and Proteasomes
an exergonic reaction is... (spontaneous/not spontaneous)
Spontaneous
What process does glycolysis use?
Substrate Level phosphorylation
What process does the citric acid cycle use?
Substrate level phosphorylation
Equation of how Enzymes function in reaction
Substrate(s) + Enzyme = Product(s) + Enzyme
Role of anabolic pathways
Synthesis of cellular components; Endergonic. MUST BE COUPLED WITH EXERGONIC REACTION!
reversible inhibitors
The activity of the enzyme is fully restored after removing the inhibitor, use of non covalent interactions
What is the role of ubiquitin?
Ubiquitin tags proteins for degradation
What is fermentation?
breakdown of organic molecules without net oxidation. Produces 2 ATP.
How can competitive inhibition be overcome?
increasing substrate concentration
Where does the citric acid cycle/Kreb's cycle occur?
mitochondrial matrix
simple diffusion
movement of a solute from an area of high concentration to an area of low concentration
What pH do cytosolic enzymes operate best at?
neutral, around 7.2. (the pH of human cells)
Altering the three-dimensional structure of an enzyme might...
prevent the substrate from binding the enzyme's active site.
What is the role of the rough ER?
protein synthesis, transport and sorting; ribosomes synthesize proteins into RER. Modification of proteins, ex: glycosylation.
What is the process for the oxidation of Pyruvate before it can enter the citric acid cycle?
pyruvate is transported to the mitochondrial matrix. A molecule of CO2 is removed for each pyruvate (C3). Remaining Acetyl group is attached to CoA to make acetyl CoA. Yield is 1 NADH for each pyruvate
active transport
the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.
facilitated diffusion
the transport of substances through a cell membrane along a concentration gradient with the aid of carrier proteins
