Bio 102 Unit 5

Endocytosis

taking up of large and small molecules by cells

Pinocytosis

ingestion of fluid and dissolved molecules by cells, sometimes referred to as “cell drinking”

Phagocytosis

ingestion of large particles by cells

Phagosomes

Vesicles that help the cell perform phagocytosis

transport vesicles

membrane-bound “bubbles” that are used for endo and exocytosis

pseudopodium (plural pseudopodia)

extensions of the cell that reach out and grab large particles

Exocytosis

secretion of products by cells

Clathrin

protein that coats vesicles and facilitate endocytosis

Coated Vesicle

Vesicle coated with clathrin that has now separated from the cell membrane

Receptor-Mediated Endocytosis

Form of endocytosis where receptors on the cell surface capture macromolecules to be ingested

FH

also known as Familial hypercholesterolemia, it is a disease where cells never internalize LDL cholesterol, and as a result keeps making cholesterol, thinking there isn’t any

What is the health impact of FH?

Very high levels of LDL cholesterol in the bloodstream lead to heart attacks and strokes

statins

a class of drugs to lower cholesterol levels in the blood by blocking the enzymes that continuously make it, such as HMG-CoA reductase

Signal Transduction

process by which cells convert an extracellular stimuli into an internal response

Endocrine signaling

a form of cell signaling where the signaling molecules signal far away cells in the body

Hormones

Type of endocrine signaling molecule commonly made by the body (ex. testosterone, estrogen)

Endocrine cells

type of cell in animals that make hormones

Paracrine Signaling

A form of cell signaling where the signal molecule remains close to the cell, sometimes signals itself

Autocrine signaling

cell signals itself via paracrine signaling, amplifies its signal

Neuronal Signaling

a subset of paracrine signalling. synapses between neurons secrete nuerotransmitters

Contact-Dependent Signaling

transmission of signal by direct cell-to-cell attachment

positive regulation

cell signals influence the activity of the previous signal, amplification cascade

negative regulation

high levels of a product turn off the protein that makes it, turn back on when levels drop

ion channel coupled receptors

receptors that function as channels where the binding of a signaling molecule causes ions to rush in or out of the cell on their concentration gradient

G-Protein Coupled Receptor

membrane-bound GTP binding activates a signaling cascade when the receptor separates an alpha-beta-gamma protein complex

Enzyme-Coupled Receptor

stimulated receptor activates enzymatic pathways

Nitric Oxide

Tiny signaling molecule that can diffuse across the membrane:

activates guanylyl cyclase to convert GTP into cyclic GMP and relax smooth muscle cells in the veins.

RTK

receptor tyrosine kinase - receptor that cross-phosphorylates secondary signalers when an extracellular signaling molecule binds

Adaptation

cells are able to respond to fluctuations in the concentration of signal molecules

Inositol Phospholipid

activation of phospholipase C by GPCR pathway cleaves this molecule into inositol 1,4, 5 - triphosphate (IP3) and diaglycerol (DAG)

IP3 and DAG

secondary signaling molecules originating from inositol phospholipid opening calcium channels on the smooth ER, activating Protein Kinase C

adenylyl cyclase

active alpha subunit of G-protein triggers this molecule, converting ATP to cAMP

Protein Kinase A

important kinase activated by cAMP which can either activate phosphorlyase kinase and break down glycogen, or serve as a transcription factor

Phosphorlyase kinase

molecule activated by cAMP, which breaks down glycogen

cyclic AMP phosphodiesterase

enzyme that breaks down cAMP and prevents the cAMP pathway from going out of control

Ras

monomeric G-protein which is activated by an enzyme coupled receptor and begins the MAP Kinase cascade

MAP kinase

secondary messenger which facilitates cell growth, either by changing protein activity or regulating transcription

PI-3 Kinase

kinase activated by an enzyme-coupled receptor and activates pathways for either cell growth by Akt or cell survival by BCL 2

Estrogen

steroid hormone mainly produced by females, which causes breast growth among other benefits

Western Blotting

technique where gel electrophoresis is used to separate a sample of proteins, then blotted onto a membrane to determine whether it responds to a molecule added to it

Tamoxifen

a drug used to treat many breast cancers by blocking the estrogen receptor in breast cells, stunting growth

BPA

material previously used in many plastics that is suspected of activating the estrogen receptor, which could cause cancer