The Endomembrane System

Question 1

Endomembrane system

Answer 1

The collection of membranes inside and surrounding a eukaryotic cell, related through either direct physical contact or by the transfer of membranous vesicles; includes the plasma membrane, the nuclear envelope, the smooth and rough endoplasmic reticulum, the Golgi apparatus, lysosomes, vesicles, and vacuoles

Question 2

Rough endoplasmic reticulum

Answer 2

The portion of the endoplasmic reticulum with ribosomes attached 
Functions:
Protein synthesis
Glycosylation
Membrane synthesis

Question 3

Smooth endoplasmic reticulum

Answer 3

The portion of the endoplasmic reticulum that is free of ribosomes
Functions:
Ca2+ ion storage (eg muscle contraction)
Lipid synthesis (eg steroid sex hormones)
Poison detoxification (eg alcohol)

Question 4

Golgi apparatus

Answer 4

An organelle in eukaryotic cells consisting of stacks of membranous sacs that modify, store, and route products of the endoplasmic reticulum and synthesise some products, notably noncellulose carbohydrates

Question 5

Glycosylation

Answer 5

A reaction in which a carbohydrate, i.e. a glycosyl donor, is attached to a hydroxyl or other functional group of another molecule (a glycosyl acceptor). In biology glycosylation refers to the enzymatic process that attaches glycans to proteins, lipids, or other organic molecules.

Question 6

Chromatin

Answer 6

The complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibres that are not visible with a light microscope

Question 7

Lysosome

Answer 7

A membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm of animal cells and some protists

Question 8

Phagocytosis

Answer 8

A type of endocytosis in which large particulate substances or small organisms are taken up by a cell. It is carried out by some protists and by certain immune cells of animals (in mammals, mainly macrophages, neutrophils, and dendritic cells)

Question 9

Exocytosis

Answer 9

The cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane

Question 10

Signal peptide

Answer 10

A sequence of about 20 amino acids at or near the leading (amino) end of a polypeptide that targets it to the endoplasmic reticulum or other organelles in a eukaryotic cell

Question 11

Signal-recognition particle (SRP)

Answer 11

A protein-RNA complex that recognises a signal peptide as it emerges from a ribosome and helps direct the ribosome to the endoplasmic reticulum by binding to a receptor protein on the ER