What molecule does complex IV oxidize and what molecule does it reduce ? How many protons does complex IV pump into the intermembrane space of the mitochondria during electron transport ?

• Complex IV Oxidizes Cytochrome C

• Complex IV Reduces Oxygen

• Complex IV Pumps 2 protons into the innermembrane space for every 2 electrons ( NADH )

If a person were poisoned with oligomycin but electron transport continued in the mitochondria , would the pH of the intermembrane spece get higher ( less acidic ) or lower ( more acidic ) and why ?

• Oligomycin blocks protons from flowing through ATP synthase

• Therefore proton concentration builds up in the innermembrane space

  $$pH=-log([H^{+}])$$
  $$pH\frac{1}{\propto }[H^{+}]$$

• pH of the innermembrane space becomes lower ( more acidic )

What is the net reaction of one round of beta-oxidation of a fatty acid ?

How many acetyl-CoAs can be generated from beta-oxidation of an 18-carbon fatty acid and how many rounds of beta-oxidation can be performed on that 18-carbon fatty acid ?

• Total Acetyl-CoA = $\frac{n}{2}=\frac{18}{2}=9$$\frac{n}{2} = \frac{18}{2} = 9$

• Total β-Oxidation Rounds = $\frac{n}{2}-1=\frac{18}{2}-1=8$$\frac{n}{2} - 1 = \frac{18}{2} - 1 = 8$

Write out the reactants and products of the glycolytic reaction catalyzed by the enzyme Glyceraldehyde 3-phosphate dehydrogenase

In anaerobic conditions ( no $O_2$$O_2$ ) , how does fermentation contribute to continued ATP generation ?

• Replenishes $NA{D}^{+}$$NAD^+$ for glycolysis

What is the result of one turn of the Citric Acid Cycle ?

In fasting conditions , describe what happens to hepatic ( liver ) fructose-2,6-bisphosphate levels , phosphofructokinase activity , glycolysis , glycogenesis , gluconeogenesis , and hepatic glucose production ( you can simply write out each parameter and put an up or down arrow next to it ) and what signaling molecule regulates this response ?

• Hepatic Fructose 2,6-Bisphosphate = Decreased = Increased Kinase Activity and Decreased Phosphatase Activity on Bi-Functional Enzyme

• Phosphofructokinase Activity = Decreased = F-2,6-BP

• Glycolysis = Decreased = Less PFK1 activity

• Glucogenesis = Decreased = Glucagon

• Gluconeogenesis = Increased = Glucagon

• Hepatic Glucose Production = Increased = Glucagon

Why do cellular membranes have different compositions ? Give two examples of differences between cellular or subcellular membranes

• Different functions requires a different set of lipids

  • different anchoring lipids

  • different signaling ( internal )

1. Cellular membranes are usually phospholipids like phosphatidylcholine. Subcellular has more phosphotidylserine

2. Extracellular has ligand receptors. Intracellular side has secondary messenger components to continue signal transduction

Lipid rafts are reported to provide a more stable environment for proteins to be held in the membrane. Name one component of the lipid raft that facilitates this stability.

• cholesterol

Give an example of why it is important for a protein to be held in a specific part of a cell's membrane.

• For sperm cell , it is important to keep hydrolytic enzymes at the head position. They would be ineffective if they were allowed to freely float down to the tail.

Many proteins can move in the plasma membrane. Give an example of when it might be useful for a protein to be able to move in the membrane.

• In mitochondria , it is important for Cytochrome C to be able to flow through inner-membrane , to deliver electrons to Complex IV

If , for the cell illustrated above , $N{a}^{+}$$Na^+$ , $K^{+}$$K^+$ , and $C{l}^{-}$$Cl^-$ , are equally conductive ( permeable ) what is the ( resting ) membrane potential , and what direction ( into , out of the cell ) will $N{a}^{+}$$Na^+$ , $K^{+}$$K^+$ , and $C{l}^{-}$$Cl^-$ move.

• Let $g_{Na}=g_K=g_{Cl}=\frac{1}{3}$$g_{Na} = g_{K} = g_{Cl} = \frac{1}{3}$

• Driving Forces :

  • $K^{+}=(-20.828mV)-(-60.0mV)=39.172mV$$K^+ = \left(\ -20.828\ mV\ \right) - \left(\ -60.0\ mV \ \right) = 39.172\ mV$

    • moves out of the cell

  • $N{a}^{+}=(-20.828mV)-\left(60.0mV\right)=-80.828mV$$Na^+ = \left(\ -20.828\ mV\ \right) - \left(\ 60.0\ mV \ \right) = -80.828\ mV$

    • moves into the cell

  • $C{l}^{-}=(-20.828mV)-(-62.484mV)=41.656mV$$Cl^- = \left(\ -20.828\ mV\ \right) - \left(\ -62.484\ mV \ \right) = 41.656\ mV$

    • moves into the cell

Please describe through words and/or illustrations , the molecular mechanism by which the following ion channel types activate - how the ion channel protein transitions from the closed to the open ( activated ) state.

• A : The molecular mechanism by which voltage-gated cation channels activate

  • Voltage-gated cation channels open in response to membrane depolarization.

  • The S4 helix, which acts as the voltage sensor, contains basic amino acids ( arginine or lysine ) spaced every third residue.

  • These amino acids respond to changes in membrane voltage by moving outward , triggering a conformational change that opens the pore.

• B : The molecular mechanism by which acetylcholine receptor channels activate

  • 2 Acetyl-Choline binds between subunits. This causes TM2 segments to wrap around each other , thereby opening the pore.

Difference between affinity and efficacy

• Affinity: The ability of a drug to bind to its receptor. High-affinity drugs bind effectively at lower concentrations.

• Efficacy: The ability of a drug-receptor complex to produce a physiological response. A drug can have high affinity but low efficacy.

What is tolerance

• With repeated opioid use, receptor downregulation occurs. More ligand (drug) is required to achieve the same effect due to fewer receptors available.

What are the differences between Family 1 and Family 2 steroid receptors

• Family 1: Includes common steroids like glucocorticoids, androgens, estrogens, progesterones, and mineralocorticoids.

  • These receptors are cytosolic,

  • Upon ligand binding, the receptor forms a homodimer and translocates into the nucleus, initiating gene transcription.

• Family 2: Includes T3, retinoid acid, RXR, and vitamin D receptors.

  • These receptors are nuclear

  • After ligand binding, they form a heterodimer (often with RXR) before binding to DNA and initiating gene transcription.

Something about how CDKs and Cyclins Act on the Cell Cycle

• Growth Factor ➡️ MAP Kinase ➡️ Cyclin D ➡️ Cyclin D-Cdk4 ➡️ Rb-P ➡️ DNA Replication