BIOG 1440 Prelim 3 — Repair A: Repeat Misses (Nov 7)

L14-L18 items missed more than once or wrong after repair in the Nov 7 diagnostic. Priority order. Study first.

NF-κB: innate or adaptive? What activates it, and what does it do?

Innate. PRRs recognizing PAMPs or DAMPs activate it. It is a transcription factor that switches on innate effector genes and activates immune cells. It does NOT tell B cells to make antibodies.

What makes a B cell start producing antibodies?

Its own receptor binding a matching antigen (clonal selection), not an NF-κB signal.

Clonal selection: does antigen instruct a lymphocyte what to make?

No. Antigen SELECTS a pre-existing lymphocyte whose receptor already matches; that clone proliferates (effector + memory cells).

Where are ADH and oxytocin MADE, and where are they RELEASED?

Made in hypothalamic neurons; released from the posterior pituitary (axon terminals). The posterior lobe makes neither.

GPCR → cAMP chain: what does the G protein bind, what does adenylyl cyclase make, and what does that activate?

G protein binds GTP (not guanine) → activates adenylyl cyclase → ATP → cAMP → activates PKA, which phosphorylates target proteins.

GPCR → PLC chain: products of PIP2, and which one releases Ca2+ from where to where?

PLC cleaves PIP2 (a plasma-membrane lipid) → IP3 + DAG. IP3 opens IP3-gated channels on the ER → Ca2+ from the ER into the cytoplasm. DAG does not open the channel.

The 70% form of blood CO2 is ___ (not carbonic acid). What are the other two?

Bicarbonate (HCO3−). 23% bound to Hb (carbaminohemoglobin), 7% dissolved. Carbonic acid is only the brief intermediate that dissociates.

Fetal Hb: chain composition, the amino-acid swap, and the consequence.

α2γ2. His143 → Ser on the γ chain removes a positive charge in the BPG pocket → BPG binds weaker → higher O2 affinity → O2 moves from maternal to fetal Hb.

Bohr effect mechanism (pH arm and CO2 arm).

Low pH protonates a histidine near the β-chain C-terminus → salt bridge with an aspartate. CO2 binds Hb's amino terminus → another salt bridge. Both stabilize deoxyhemoglobin → lower O2 affinity → O2 released.

Why does a salt bridge in deoxy Hb lower O2 affinity?

Binding O2 requires switching to the oxy shape, which breaks the bridges, so O2 binding is less favorable; the curve shifts right.

C4 and CAM: first enzyme to fix carbon and its product.

PEP carboxylase fixes bicarbonate onto PEP → oxaloacetate (4C). Rubisco refixes the released CO2 later. Not carbonic anhydrase (it only hydrates CO2).

What is the difference between carbonic anhydrase's job and 'fixation'?

Carbonic anhydrase interconverts CO2 and bicarbonate (hydration). Fixation attaches carbon to an organic molecule (PEP carboxylase, Rubisco).

Phototropism: where do the proton pumps move H+, and what does that do?

Cytoplasm → cell WALL. Wall pH drops → expansins LOOSEN (not cleave) wall links → turgor pressure drives cell expansion on the shaded side.

Aldosterone vs ADH: source and effect.

Aldosterone: adrenal cortex, zona glomerulosa → kidney reabsorbs Na+ (water follows). ADH: made in hypothalamus, released from posterior pituitary → water reabsorption.

Prolactin vs oxytocin: lobe and milk effect.

Prolactin: anterior pituitary (made there), acts directly on the mammary gland. Oxytocin: posterior (made in hypothalamus) → milk ejection.

Excess cortisol: what does it break down to raise glucose?

Protein → amino acids for glucose synthesis. Glycogen breakdown belongs to epinephrine (the rapid arm).

Early type 2 diabetes: insulin level?

High (hyperinsulinemia); cells are less sensitive to it. Not all diabetes means too little insulin.

Who makes antibodies, and what do cytotoxic T cells do instead?

B cells (plasma cells) make antibodies. Cytotoxic T cells recognize antigen on MHC and kill the cell (perforin pores).

Resistance vs tolerance, with the lecture's example.

Resistance: eliminate the pathogen. Tolerance: endure the damage without clearing it (Typhoid Mary, asymptomatic carrier; ~90% of TB infections symptomless).

During exercise, what is the main trigger for faster breathing?

Falling blood pH (from CO2 → H+), sensed by the medulla and vessel sensors. Not heart rate.

Phototropism: where is light sensed?

At the shoot tip.

Two broad strategies for surviving O2's reactivity.

Detoxification (SOD, catalase, peroxidases) and avoidance (anaerobic habitats, separating in space or time, binding O2 as with leghemoglobin).