L7: Responding to the cellular environment

Flashcards covering key vocabulary and concepts from a lecture on how cells respond to their environment.

Homeostasis

The ability of an organism to maintain a stable internal environment despite changes in external conditions.

Hif-1α

A transcription factor that accumulates at low oxygen levels and induces the transcription of genes that help cells survive stress.

Prolyl Hydroxylase PHD2

An enzyme that transfers an OH group to proline residues in Hif-1α at high oxygen levels, leading to VHL binding and degradation of Hif-1α.

VHL (Von Hippel-Lindau)

A tumor-suppressor protein that binds to hydroxylated Hif-1α, leading to its polyubiquitinylation and destruction.

Nitric Oxide (NO)

A gas that diffuses rapidly through membranes and acts as an intracellular and extracellular messenger to improve O2 delivery to tissues.

NO Synthase

An enzyme that synthesizes nitric oxide in response to various agents, including acetylcholine and calcium signaling.

Soluble Guanylate Cyclase

A soluble receptor activated by nitric oxide that makes a second messenger called 3'5cGMP.

3'5cGMP

A second messenger produced by soluble guanylate cyclase that activates protein kinase G (PKG).

Protein Kinase G (PKG)

A kinase activated by cGMP that phosphorylates downstream target proteins to achieve cellular outcomes.

Nitroglycerin

A pharmaceutical agent used to relieve chest pains in angina by releasing nitric oxide and improving circulation in the heart.

Sildenafil

A pharmaceutical agent (Viagra) that inhibits cGMP phosphodiesterase, potentiating the action of NO by preventing cGMP breakdown.

Rhodopsin

GPCR in rod cells that is stimulated by light, leading to closure of cGMP-gated Na+/Ca2+ channels.

cGMP-gated Na+/Ca2+ channels

Cation channels in the plasma membrane of the outer segment of rod cells that close in response to cytosolic signals, producing a change in membrane potential.

Transducin

The Gαt subunit of the G-protein that activates a phosphodiesterase, breaking down cGMP in response to light.

Arrestin

A protein that binds to phosphorylated rhodopsin to terminate the light signal in rod cells.

Circadian Rhythms

Approximately 24-hour rhythms exhibited by all organisms, driven by molecular clocks within cells and reset by external cues.

PERIOD and TIMELESS (PER and TIM)

Transcriptional repressors that are part of a negative feedback loop controlling gene expression in circadian clocks.

CLOCK and CYCLE (CLK and CYC)

Transcriptional activators that are part of a negative feedback loop controlling gene expression in circadian clocks.

CRY

Light-sensitive protein in Drosophila that undergoes a conformational change in response to light, releasing TIM from PER and CLK/CYC.

Suprachiasmatic Nucleus (SCN)

The master clock in mammals, located in the brain, that receives light signals from the retina and sends signals to regulate molecular clocks throughout the body.

Melatonin

A hormone released by the pineal gland that modulates the onset of sleep.

Vertebrate somite formation

Refers to the fact that Temporal oscillation of gene expression in the presomitic mesoderm is converted into a spatial alternating pattern of gene expression in the formed somites.