The Cell Flashcards
What are inclusions?
Accumulations of material that is not metabolically active
What phospholipids is the biological membrane built of?
Choline phospholipids, amine phospholipids, phosphatidylinositol
What are the key features of glycolipids in the biological membrane?
Have sugar residues, occur in the outer layer of the bilayer, participate in the formation of glycocalyx
What are the two classes of membrane proteins?
Peripheral (attached to phospholipids or transmembrane proteins) and Transmembrane (multi-pass or single-pass)
What functional classes of membrane proteins are there?
Transporters, linkers, receptors, enzymes
What types of controlled transport across the biological membrane are there?
Channels, carriers, pumps, translocons, ABC transporters
What types of channels are there?
Voltage-gated, ligand-gated, mechanically-gated
What is meant by uniport?
When carriers and pumps only transport one substance
What is meant by antiport?
When 2 substances are transported in opposite directions at the same time
What is meant by symport?
When 2 substances are transported in the same direction at the same time
What do translocons do?
They allow proteins to pass across the bio membrane in unfolded state
What do ABC transporters do?
They transport large molecules like drugs and peptides
What is the anterograde pathway?
ER —> Golgi —> Cell membrane
What is the retrograde pathway?
Cell membrane —> endosomes —> lysosomes
What are lipid rafts?
A specialized area of the cell membrane that is rich in cholesterol and glycolipids. The rafts are rigid and “float” in the lipid belayer. They carry sets of proteins which require close proximity to each other to function
What are caveolae?
A specialized area in the cell membrane, that is formed from lipid rafts by attachment of caveolin and invagination. They participate in pinocytosis
What are coated pits?
A specialized area in the cell membrane that is formed from lipid rafts by attachment of clathrin and invagination. They participate in receptor-mediated endocytosis
What do cadherins adhere?
cell-cell (of same type)
What do selectins adhere?
Cell-cell (cells of different type)
What does the immunoglobulins superfamily adhere?
Cell-cell (different types)
What do integrins adhere?
Mostly cell-extra cellular matrix, but sometimes cell-cell (of different types)
Membranes of which organelles do not participate in membrane trafficking?
Mitochondria and peroxisomes
What type of chromatin is transcriptionally inactive?
Euchromatin
What type of chromatin is transcriptionally active?
Heterochromatin
What is constitutive heterochromatin?
Noncoding or permanently inactive heterochromatin
What is facultative heterochromatin?
Temporarily inactive heterochromatin
What regions of the nucleolus are there?
Pale fibrillar centers, dense fibrillar components, and granular components
What do pale fibrillar centers contain?
rDNA (transcriptionally inactive)
What do dense fibrillar components contain?
Freshly transcribed rRNA
What do granular components contain?
Ribosomal subunits (mainly large)
What is the main function of the nuclear envelope?
It mediates the nucleo-cytoplasmic transport of substances via special pores (nuclear pores)
