Cell Biology Concepts and Organelles Overview

Ribosomes

Complexes that are composed of RNA & Protein.

Nucleolus

An organelle that is not enclosed by a membrane.

RER

An organelle that has a membrane continuous with the nucleus.

Smooth ER

Plays a role in lipid synthesis.

Pulse-chase

Refers to pulsing radioactive marker & tracking protein wherever it goes.

N-terminus signal sequence

Recognized by SRP.

ER lumen

Proteins destined for this location must pass through translocon.

Flippases

Transport some membrane lipids to other leaf.

Chaperone proteins

Play a role in protein folding & removal of coat protein.

Intermediate filaments

Examples include lamins.

Spectrin

An actin binding protein involved in the formation of networks.

Polarity of cytoskeletal filaments

Important for cellular function.

Myosin

Dissociates when ATP binds to it.

Calcium

Key regulator of muscle contraction.

Phospholipid bilayer asymmetry

Causes distribution of cholesterol.

Glycocalyx

Refers to the glucose layer on the cell.

Hemidesmosomes

Not involved in cell to cell junctions.

Adheron junctions

Actin filaments bind to these structures.

Tight junctions

So close there is no space between them.

Selectins

Cell surface receptors that bind to carbohydrates.

Clathrin budding

Initiated by ARFI, a GTP binding protein.

KDEL sequence defect

Results in proteins not getting recycled to the ER.

Mitochondria & Chloroplasts

Proteins are synthesized in the matrix & stroma.

Stroma

Does not involve the conversion of fatty acids to Acyl CoA.

Intermembrane space of mitochondria

Fluid composition resembles cytosol due to free-flow through porins.

Proton gradient in mitochondria

Established by pumping protons into the intermembrane space.

NADH

Involved in oxidative phosphorylation.

Ultimate source of electrons in light reactions of photosynthesis

Water (H₂O).

Actin filaments

Smallest protein filament in the cytoskeleton.