cell + molec exam 3

steps of the Na+ K+ pump

1. 3 Na⁺ bind to the pump on the inside of the cell.

2. ATP is hydrolyzed, phosphorylating the pump.

3. Conformational change: The pump opens outward and releases 3 Na⁺ outside the cell.

4. 2 K⁺ bind to the pump from outside the cell.

5. Dephosphorylation: The phosphate group is released.

6. Conformational change: The pump returns to its original shape and releases 2 K⁺ inside the cell

steps of an action potential

1. Resting potential: −60 mV; voltage-gated channels closed.

2. Threshold: ~−50 mV; action potential triggered.

3. Depolarization: Na⁺ channels open; Na⁺ enters.

4. Peak: Na⁺ channels inactivate; K⁺ channels open.

5. Repolarization: K⁺ exits; inside becomes negative.

6. Hyperpolarization: K⁺ channels close slowly; membrane becomes extra negative.

7. Resting potential restored: Channels reset; ion gradients maintained by the Na⁺/K⁺ pump

closed → open → inactivated → closed

ready Na+ in No Na+

steps of rolling leukocytes

1. cytokines are released at inflammation sites

2. endothelial cells to express selectins

3. These bind to carbohydrates on the neutrophils which allows them to stick and bind to the blood vessel walls

4. The binding interaction allows the neutrophils to roll along the vessel walls until they find an exit point

5. They stick to this spot and move in between the endothelial cells to enter the adjacent connective tissue

Where does pyruvate oxidation happen in the cell? What enzyme is responsible for converting pyruvate into acetyl CoA?

It is converted into acetyl CoA in the mitochondrial matrix by the enzyme pyruvate dehydrogenase

steps of glucose uptake

1. glucose is taken up from the guy lumen into the cell against its concentration gradient (Na+ driven symport)

2. glucose leaves cell via passive glucose uniporter into surrounding tissue

3. Na+K+ pump maintains membrane gradient

4. Tight junctions keep apical symporters and basolateral uniporters from mixing

where does glycolysis happen?

mitochondrial matrix

where does pyruvate oxidation happen?

in the mitochondrial matrix

TCA cycle products per 1 acetyl-CoA?

3 NADH, 1 FADH₂, 1 GTP, 2 CO₂.

TCA cycle products per 1 glucose (2 cycles)?

6 NADH, 2 FADH₂, 2 GTP, 4 CO₂.

how do detergents work?

their hydrophobic tail disrupts the interactions that hold the bilayer together. They separate membrane lipids and proteins from the membrane and surround them in micelles

antiport example

ADP-ATP antiport

symport example

Na+ driven glucose symport

steps of cellular metabolism

1. breakdown of large food molecule into simple subunits (digestion)

2. breakdown of subunits into acetyl coA ((includes glycolysis and other breakdown pathways, in matrix)

3. oxidation of acetyl group (Krebs cycle, in matrix)

3 main stages of glycolysis

1. energy investment

2. cleavage of the 6-C sugar into 2 3-C sugars

3. energy generation

aerobic NAD+ regeneration

NADH donates e- to ETC

anaerobic NAD+ regeneration

cell relies on fermentation to oxidize NADH

Net products of the Kreb cycle for each turn

3 NADH, 1 FADH2, 1 GTP, 2 CO2

anabolic substrate conversion

convert substrates into amino acids, nucleotides, lipids

glycolysis step 3 vs gluconeogenesis

• Glucose-6-phosphate → fructose-6-phosphate happens in step 2; step 3 is fructose-6-phosphate → fructose-1,6-bisphosphate, using 1 ATP and enzyme PFK-1.

• Gluconeogenesis: Bypasses this irreversible step using fructose-1,6-bisphosphatase, converting fructose-1,6-bisphosphate → fructose-6-phosphate and releasing Pi.